1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
/*
Open Asset Import Library (assimp)
----------------------------------------------------------------------

Copyright (c) 2006-2019, assimp team

All rights reserved.

Redistribution and use of this software in source and binary forms,
with or without modification, are permitted provided that the
following conditions are met:

* Redistributions of source code must retain the above
copyright notice, this list of conditions and the
following disclaimer.

* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the
following disclaimer in the documentation and/or other
materials provided with the distribution.

* Neither the name of the assimp team, nor the names of its
contributors may be used to endorse or promote products
derived from this software without specific prior
written permission of the assimp team.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

----------------------------------------------------------------------
*/
#ifndef ASSIMP_BUILD_NO_EXPORT
#ifndef ASSIMP_BUILD_NO_FBX_EXPORTER

#include "FBXExporter.h"
#include "FBXExportNode.h"
#include "FBXExportProperty.h"
#include "FBXCommon.h"
#include "FBXUtil.h"

#include <assimp/version.h> // aiGetVersion
#include <assimp/IOSystem.hpp>
#include <assimp/Exporter.hpp>
#include <assimp/DefaultLogger.hpp>
#include <assimp/StreamWriter.h> // StreamWriterLE
#include <assimp/Exceptional.h> // DeadlyExportError
#include <assimp/material.h> // aiTextureType
#include <assimp/scene.h>
#include <assimp/mesh.h>

// Header files, standard library.
#include <memory> // shared_ptr
#include <string>
#include <sstream> // stringstream
#include <ctime> // localtime, tm_*
#include <map>
#include <set>
#include <vector>
#include <array>
#include <unordered_set>
#include <numeric>

// RESOURCES:
// https://code.blender.org/2013/08/fbx-binary-file-format-specification/
// https://wiki.blender.org/index.php/User:Mont29/Foundation/FBX_File_Structure

const ai_real DEG = ai_real( 57.29577951308232087679815481 ); // degrees per radian

using namespace Assimp;
using namespace Assimp::FBX;

// some constants that we'll use for writing metadata
namespace Assimp {
namespace FBX {
    const std::string EXPORT_VERSION_STR = "7.4.0";
    const uint32_t EXPORT_VERSION_INT = 7400; // 7.4 == 2014/2015
    // FBX files have some hashed values that depend on the creation time field,
    // but for now we don't actually know how to generate these.
    // what we can do is set them to a known-working version.
    // this is the data that Blender uses in their FBX export process.
    const std::string GENERIC_CTIME = "1970-01-01 10:00:00:000";
    const std::string GENERIC_FILEID =
        "\x28\xb3\x2a\xeb\xb6\x24\xcc\xc2\xbf\xc8\xb0\x2a\xa9\x2b\xfc\xf1";
    const std::string GENERIC_FOOTID =
        "\xfa\xbc\xab\x09\xd0\xc8\xd4\x66\xb1\x76\xfb\x83\x1c\xf7\x26\x7e";
    const std::string FOOT_MAGIC =
        "\xf8\x5a\x8c\x6a\xde\xf5\xd9\x7e\xec\xe9\x0c\xe3\x75\x8f\x29\x0b";
    const std::string COMMENT_UNDERLINE =
        ";------------------------------------------------------------------";
}

    // ---------------------------------------------------------------------
    // Worker function for exporting a scene to binary FBX.
    // Prototyped and registered in Exporter.cpp
    void ExportSceneFBX (
        const char* pFile,
        IOSystem* pIOSystem,
        const aiScene* pScene,
        const ExportProperties* pProperties
    ){
        // initialize the exporter
        FBXExporter exporter(pScene, pProperties);

        // perform binary export
        exporter.ExportBinary(pFile, pIOSystem);
    }

    // ---------------------------------------------------------------------
    // Worker function for exporting a scene to ASCII FBX.
    // Prototyped and registered in Exporter.cpp
    void ExportSceneFBXA (
        const char* pFile,
        IOSystem* pIOSystem,
        const aiScene* pScene,
        const ExportProperties* pProperties

    ){
        // initialize the exporter
        FBXExporter exporter(pScene, pProperties);

        // perform ascii export
        exporter.ExportAscii(pFile, pIOSystem);
    }

} // end of namespace Assimp

FBXExporter::FBXExporter ( const aiScene* pScene, const ExportProperties* pProperties )
: binary(false)
, mScene(pScene)
, mProperties(pProperties)
, outfile()
, connections()
, mesh_uids()
, material_uids()
, node_uids() {
    // will probably need to determine UIDs, connections, etc here.
    // basically anything that needs to be known
    // before we start writing sections to the stream.
}

void FBXExporter::ExportBinary (
    const char* pFile,
    IOSystem* pIOSystem
){
    // remember that we're exporting in binary mode
    binary = true;

    // we're not currently using these preferences,
    // but clang will cry about it if we never touch it.
    // TODO: some of these might be relevant to export
    (void)mProperties;

    // open the indicated file for writing (in binary mode)
    outfile.reset(pIOSystem->Open(pFile,"wb"));
    if (!outfile) {
        throw DeadlyExportError(
            "could not open output .fbx file: " + std::string(pFile)
        );
    }

    // first a binary-specific file header
    WriteBinaryHeader();

    // the rest of the file is in node entries.
    // we have to serialize each entry before we write to the output,
    // as the first thing we write is the byte offset of the _next_ entry.
    // Either that or we can skip back to write the offset when we finish.
    WriteAllNodes();

    // finally we have a binary footer to the file
    WriteBinaryFooter();

    // explicitly release file pointer,
    // so we don't have to rely on class destruction.
    outfile.reset();
}

void FBXExporter::ExportAscii (
    const char* pFile,
    IOSystem* pIOSystem
){
    // remember that we're exporting in ascii mode
    binary = false;

    // open the indicated file for writing in text mode
    outfile.reset(pIOSystem->Open(pFile,"wt"));
    if (!outfile) {
        throw DeadlyExportError(
            "could not open output .fbx file: " + std::string(pFile)
        );
    }

    // write the ascii header
    WriteAsciiHeader();

    // write all the sections
    WriteAllNodes();

    // make sure the file ends with a newline.
    // note: if the file is opened in text mode,
    // this should do the right cross-platform thing.
    outfile->Write("\n", 1, 1);

    // explicitly release file pointer,
    // so we don't have to rely on class destruction.
    outfile.reset();
}

void FBXExporter::WriteAsciiHeader()
{
    // basically just a comment at the top of the file
    std::stringstream head;
    head << "; FBX " << EXPORT_VERSION_STR << " project file\n";
    head << "; Created by the Open Asset Import Library (Assimp)\n";
    head << "; http://assimp.org\n";
    head << "; -------------------------------------------------\n";
    const std::string ascii_header = head.str();
    outfile->Write(ascii_header.c_str(), ascii_header.size(), 1);
}

void FBXExporter::WriteAsciiSectionHeader(const std::string& title)
{
    StreamWriterLE outstream(outfile);
    std::stringstream s;
    s << "\n\n; " << title << '\n';
    s << FBX::COMMENT_UNDERLINE << "\n";
    outstream.PutString(s.str());
}

void FBXExporter::WriteBinaryHeader()
{
    // first a specific sequence of 23 bytes, always the same
    const char binary_header[24] = "Kaydara FBX Binary\x20\x20\x00\x1a\x00";
    outfile->Write(binary_header, 1, 23);

    // then FBX version number, "multiplied" by 1000, as little-endian uint32.
    // so 7.3 becomes 7300 == 0x841C0000, 7.4 becomes 7400 == 0xE81C0000, etc
    {
        StreamWriterLE outstream(outfile);
        outstream.PutU4(EXPORT_VERSION_INT);
    } // StreamWriter destructor writes the data to the file

    // after this the node data starts immediately
    // (probably with the FBXHEaderExtension node)
}

void FBXExporter::WriteBinaryFooter()
{
    outfile->Write(NULL_RECORD.c_str(), NULL_RECORD.size(), 1);

    outfile->Write(GENERIC_FOOTID.c_str(), GENERIC_FOOTID.size(), 1);

    // here some padding is added for alignment to 16 bytes.
    // if already aligned, the full 16 bytes is added.
    size_t pos = outfile->Tell();
    size_t pad = 16 - (pos % 16);
    for (size_t i = 0; i < pad; ++i) {
        outfile->Write("\x00", 1, 1);
    }

    // not sure what this is, but it seems to always be 0 in modern files
    for (size_t i = 0; i < 4; ++i) {
        outfile->Write("\x00", 1, 1);
    }

    // now the file version again
    {
        StreamWriterLE outstream(outfile);
        outstream.PutU4(EXPORT_VERSION_INT);
    } // StreamWriter destructor writes the data to the file

    // and finally some binary footer added to all files
    for (size_t i = 0; i < 120; ++i) {
        outfile->Write("\x00", 1, 1);
    }
    outfile->Write(FOOT_MAGIC.c_str(), FOOT_MAGIC.size(), 1);
}

void FBXExporter::WriteAllNodes ()
{
    // header
    // (and fileid, creation time, creator, if binary)
    WriteHeaderExtension();

    // global settings
    WriteGlobalSettings();

    // documents
    WriteDocuments();

    // references
    WriteReferences();

    // definitions
    WriteDefinitions();

    // objects
    WriteObjects();

    // connections
    WriteConnections();

    // WriteTakes? (deprecated since at least 2015 (fbx 7.4))
}

//FBXHeaderExtension top-level node
void FBXExporter::WriteHeaderExtension ()
{
    if (!binary) {
        // no title, follows directly from the top comment
    }
    FBX::Node n("FBXHeaderExtension");
    StreamWriterLE outstream(outfile);
    int indent = 0;

    // begin node
    n.Begin(outstream, binary, indent);

    // write properties
    // (none)

    // finish properties
    n.EndProperties(outstream, binary, indent, 0);

    // begin children
    n.BeginChildren(outstream, binary, indent);

    indent = 1;

    // write child nodes
    FBX::Node::WritePropertyNode(
        "FBXHeaderVersion", int32_t(1003), outstream, binary, indent
    );
    FBX::Node::WritePropertyNode(
        "FBXVersion", int32_t(EXPORT_VERSION_INT), outstream, binary, indent
    );
    if (binary) {
        FBX::Node::WritePropertyNode(
            "EncryptionType", int32_t(0), outstream, binary, indent
        );
    }

    FBX::Node CreationTimeStamp("CreationTimeStamp");
    time_t rawtime;
    time(&rawtime);
    struct tm * now = localtime(&rawtime);
    CreationTimeStamp.AddChild("Version", int32_t(1000));
    CreationTimeStamp.AddChild("Year", int32_t(now->tm_year + 1900));
    CreationTimeStamp.AddChild("Month", int32_t(now->tm_mon + 1));
    CreationTimeStamp.AddChild("Day", int32_t(now->tm_mday));
    CreationTimeStamp.AddChild("Hour", int32_t(now->tm_hour));
    CreationTimeStamp.AddChild("Minute", int32_t(now->tm_min));
    CreationTimeStamp.AddChild("Second", int32_t(now->tm_sec));
    CreationTimeStamp.AddChild("Millisecond", int32_t(0));
    CreationTimeStamp.Dump(outstream, binary, indent);

    std::stringstream creator;
    creator << "Open Asset Import Library (Assimp) " << aiGetVersionMajor()
            << "." << aiGetVersionMinor() << "." << aiGetVersionRevision();
    FBX::Node::WritePropertyNode(
        "Creator", creator.str(), outstream, binary, indent
    );

    //FBX::Node sceneinfo("SceneInfo");
    //sceneinfo.AddProperty("GlobalInfo" + FBX::SEPARATOR + "SceneInfo");
    // not sure if any of this is actually needed,
    // so just write an empty node for now.
    //sceneinfo.Dump(outstream, binary, indent);

    indent = 0;

    // finish node
    n.End(outstream, binary, indent, true);

    // that's it for FBXHeaderExtension...
    if (!binary) { return; }

    // but binary files also need top-level FileID, CreationTime, Creator:
    std::vector<uint8_t> raw(GENERIC_FILEID.size());
    for (size_t i = 0; i < GENERIC_FILEID.size(); ++i) {
        raw[i] = uint8_t(GENERIC_FILEID[i]);
    }
    FBX::Node::WritePropertyNode(
        "FileId", raw, outstream, binary, indent
    );
    FBX::Node::WritePropertyNode(
        "CreationTime", GENERIC_CTIME, outstream, binary, indent
    );
    FBX::Node::WritePropertyNode(
        "Creator", creator.str(), outstream, binary, indent
    );
}

void FBXExporter::WriteGlobalSettings ()
{
    if (!binary) {
        // no title, follows directly from the header extension
    }
    FBX::Node gs("GlobalSettings");
    gs.AddChild("Version", int32_t(1000));

    FBX::Node p("Properties70");
    p.AddP70int("UpAxis", 1);
    p.AddP70int("UpAxisSign", 1);
    p.AddP70int("FrontAxis", 2);
    p.AddP70int("FrontAxisSign", 1);
    p.AddP70int("CoordAxis", 0);
    p.AddP70int("CoordAxisSign", 1);
    p.AddP70int("OriginalUpAxis", 1);
    p.AddP70int("OriginalUpAxisSign", 1);
    p.AddP70double("UnitScaleFactor", 1.0);
    p.AddP70double("OriginalUnitScaleFactor", 1.0);
    p.AddP70color("AmbientColor", 0.0, 0.0, 0.0);
    p.AddP70string("DefaultCamera", "Producer Perspective");
    p.AddP70enum("TimeMode", 11);
    p.AddP70enum("TimeProtocol", 2);
    p.AddP70enum("SnapOnFrameMode", 0);
    p.AddP70time("TimeSpanStart", 0); // TODO: animation support
    p.AddP70time("TimeSpanStop", FBX::SECOND); // TODO: animation support
    p.AddP70double("CustomFrameRate", -1.0);
    p.AddP70("TimeMarker", "Compound", "", ""); // not sure what this is
    p.AddP70int("CurrentTimeMarker", -1);
    gs.AddChild(p);

    gs.Dump(outfile, binary, 0);
}

void FBXExporter::WriteDocuments ()
{
    if (!binary) {
        WriteAsciiSectionHeader("Documents Description");
    }
    
    // not sure what the use of multiple documents would be,
    // or whether any end-application supports it
    FBX::Node docs("Documents");
    docs.AddChild("Count", int32_t(1));
    FBX::Node doc("Document");

    // generate uid
    int64_t uid = generate_uid();
    doc.AddProperties(uid, "", "Scene");
    FBX::Node p("Properties70");
    p.AddP70("SourceObject", "object", "", ""); // what is this even for?
    p.AddP70string("ActiveAnimStackName", ""); // should do this properly?
    doc.AddChild(p);

    // UID for root node in scene hierarchy.
    // always set to 0 in the case of a single document.
    // not sure what happens if more than one document exists,
    // but that won't matter to us as we're exporting a single scene.
    doc.AddChild("RootNode", int64_t(0));

    docs.AddChild(doc);
    docs.Dump(outfile, binary, 0);
}

void FBXExporter::WriteReferences ()
{
    if (!binary) {
        WriteAsciiSectionHeader("Document References");
    }
    // always empty for now.
    // not really sure what this is for.
    FBX::Node n("References");
    n.force_has_children = true;
    n.Dump(outfile, binary, 0);
}


// ---------------------------------------------------------------
// some internal helper functions used for writing the definitions
// (before any actual data is written)
// ---------------------------------------------------------------

size_t count_nodes(const aiNode* n) {
    size_t count = 1;
    for (size_t i = 0; i < n->mNumChildren; ++i) {
        count += count_nodes(n->mChildren[i]);
    }
    return count;
}

bool has_phong_mat(const aiScene* scene)
{
    // just search for any material with a shininess exponent
    for (size_t i = 0; i < scene->mNumMaterials; ++i) {
        aiMaterial* mat = scene->mMaterials[i];
        float shininess = 0;
        mat->Get(AI_MATKEY_SHININESS, shininess);
        if (shininess > 0) {
            return true;
        }
    }
    return false;
}

size_t count_images(const aiScene* scene) {
    std::unordered_set<std::string> images;
    aiString texpath;
    for (size_t i = 0; i < scene->mNumMaterials; ++i) {
        aiMaterial* mat = scene->mMaterials[i];
        for (
            size_t tt = aiTextureType_DIFFUSE;
            tt < aiTextureType_UNKNOWN;
            ++tt
        ){
            const aiTextureType textype = static_cast<aiTextureType>(tt);
            const size_t texcount = mat->GetTextureCount(textype);
            for (unsigned int j = 0; j < texcount; ++j) {
                mat->GetTexture(textype, j, &texpath);
                images.insert(std::string(texpath.C_Str()));
            }
        }
    }
    return images.size();
}

size_t count_textures(const aiScene* scene) {
    size_t count = 0;
    for (size_t i = 0; i < scene->mNumMaterials; ++i) {
        aiMaterial* mat = scene->mMaterials[i];
        for (
            size_t tt = aiTextureType_DIFFUSE;
            tt < aiTextureType_UNKNOWN;
            ++tt
        ){
            // TODO: handle layered textures
            if (mat->GetTextureCount(static_cast<aiTextureType>(tt)) > 0) {
                count += 1;
            }
        }
    }
    return count;
}

size_t count_deformers(const aiScene* scene) {
    size_t count = 0;
    for (size_t i = 0; i < scene->mNumMeshes; ++i) {
        const size_t n = scene->mMeshes[i]->mNumBones;
        if (n) {
            // 1 main deformer, 1 subdeformer per bone
            count += n + 1;
        }
    }
    return count;
}

void FBXExporter::WriteDefinitions ()
{
    // basically this is just bookkeeping:
    // determining how many of each type of object there are
    // and specifying the base properties to use when otherwise unspecified.

    // ascii section header
    if (!binary) {
        WriteAsciiSectionHeader("Object definitions");
    }

    // we need to count the objects
    int32_t count;
    int32_t total_count = 0;

    // and store them
    std::vector<FBX::Node> object_nodes;
    FBX::Node n, pt, p;<--- Shadowed declaration

    // GlobalSettings
    // this seems to always be here in Maya exports
    n = FBX::Node("ObjectType", "GlobalSettings");
    count = 1;
    n.AddChild("Count", count);
    object_nodes.push_back(n);
    total_count += count;

    // AnimationStack / FbxAnimStack
    // this seems to always be here in Maya exports,
    // but no harm seems to come of leaving it out.
    count = mScene->mNumAnimations;
    if (count) {
        n = FBX::Node("ObjectType", "AnimationStack");
        n.AddChild("Count", count);
        pt = FBX::Node("PropertyTemplate", "FbxAnimStack");
        p = FBX::Node("Properties70");
        p.AddP70string("Description", "");
        p.AddP70time("LocalStart", 0);
        p.AddP70time("LocalStop", 0);
        p.AddP70time("ReferenceStart", 0);
        p.AddP70time("ReferenceStop", 0);
        pt.AddChild(p);
        n.AddChild(pt);
        object_nodes.push_back(n);
        total_count += count;
    }

    // AnimationLayer / FbxAnimLayer
    // this seems to always be here in Maya exports,
    // but no harm seems to come of leaving it out.
    // Assimp doesn't support animation layers,
    // so there will be one per aiAnimation
    count = mScene->mNumAnimations;
    if (count) {
        n = FBX::Node("ObjectType", "AnimationLayer");
        n.AddChild("Count", count);
        pt = FBX::Node("PropertyTemplate", "FBXAnimLayer");
        p = FBX::Node("Properties70");
        p.AddP70("Weight", "Number", "", "A", double(100));
        p.AddP70bool("Mute", 0);
        p.AddP70bool("Solo", 0);
        p.AddP70bool("Lock", 0);
        p.AddP70color("Color", 0.8, 0.8, 0.8);
        p.AddP70("BlendMode", "enum", "", "", int32_t(0));
        p.AddP70("RotationAccumulationMode", "enum", "", "", int32_t(0));
        p.AddP70("ScaleAccumulationMode", "enum", "", "", int32_t(0));
        p.AddP70("BlendModeBypass", "ULongLong", "", "", int64_t(0));
        pt.AddChild(p);
        n.AddChild(pt);
        object_nodes.push_back(n);
        total_count += count;
    }

    // NodeAttribute
    // this is completely absurd.
    // there can only be one "NodeAttribute" template,
    // but FbxSkeleton, FbxCamera, FbxLight all are "NodeAttributes".
    // so if only one exists we should set the template for that,
    // otherwise... we just pick one :/.
    // the others have to set all their properties every instance,
    // because there's no template.
    count = 1; // TODO: select properly<--- Assignment 'count=1', assigned value is 1
    if (count) {<--- Condition 'count' is always true
        // FbxSkeleton
        n = FBX::Node("ObjectType", "NodeAttribute");
        n.AddChild("Count", count);
        pt = FBX::Node("PropertyTemplate", "FbxSkeleton");
        p = FBX::Node("Properties70");
        p.AddP70color("Color", 0.8, 0.8, 0.8);
        p.AddP70double("Size", 33.333333333333);
        p.AddP70("LimbLength", "double", "Number", "H", double(1));
        // note: not sure what the "H" flag is for - hidden?
        pt.AddChild(p);
        n.AddChild(pt);
        object_nodes.push_back(n);
        total_count += count;
    }

    // Model / FbxNode
    // <~~ node hierarchy
    count = int32_t(count_nodes(mScene->mRootNode)) - 1; // (not counting root node)
    if (count) {
        n = FBX::Node("ObjectType", "Model");
        n.AddChild("Count", count);
        pt = FBX::Node("PropertyTemplate", "FbxNode");
        p = FBX::Node("Properties70");
        p.AddP70enum("QuaternionInterpolate", 0);
        p.AddP70vector("RotationOffset", 0.0, 0.0, 0.0);
        p.AddP70vector("RotationPivot", 0.0, 0.0, 0.0);
        p.AddP70vector("ScalingOffset", 0.0, 0.0, 0.0);
        p.AddP70vector("ScalingPivot", 0.0, 0.0, 0.0);
        p.AddP70bool("TranslationActive", 0);
        p.AddP70vector("TranslationMin", 0.0, 0.0, 0.0);
        p.AddP70vector("TranslationMax", 0.0, 0.0, 0.0);
        p.AddP70bool("TranslationMinX", 0);
        p.AddP70bool("TranslationMinY", 0);
        p.AddP70bool("TranslationMinZ", 0);
        p.AddP70bool("TranslationMaxX", 0);
        p.AddP70bool("TranslationMaxY", 0);
        p.AddP70bool("TranslationMaxZ", 0);
        p.AddP70enum("RotationOrder", 0);
        p.AddP70bool("RotationSpaceForLimitOnly", 0);
        p.AddP70double("RotationStiffnessX", 0.0);
        p.AddP70double("RotationStiffnessY", 0.0);
        p.AddP70double("RotationStiffnessZ", 0.0);
        p.AddP70double("AxisLen", 10.0);
        p.AddP70vector("PreRotation", 0.0, 0.0, 0.0);
        p.AddP70vector("PostRotation", 0.0, 0.0, 0.0);
        p.AddP70bool("RotationActive", 0);
        p.AddP70vector("RotationMin", 0.0, 0.0, 0.0);
        p.AddP70vector("RotationMax", 0.0, 0.0, 0.0);
        p.AddP70bool("RotationMinX", 0);
        p.AddP70bool("RotationMinY", 0);
        p.AddP70bool("RotationMinZ", 0);
        p.AddP70bool("RotationMaxX", 0);
        p.AddP70bool("RotationMaxY", 0);
        p.AddP70bool("RotationMaxZ", 0);
        p.AddP70enum("InheritType", 0);
        p.AddP70bool("ScalingActive", 0);
        p.AddP70vector("ScalingMin", 0.0, 0.0, 0.0);
        p.AddP70vector("ScalingMax", 1.0, 1.0, 1.0);
        p.AddP70bool("ScalingMinX", 0);
        p.AddP70bool("ScalingMinY", 0);
        p.AddP70bool("ScalingMinZ", 0);
        p.AddP70bool("ScalingMaxX", 0);
        p.AddP70bool("ScalingMaxY", 0);
        p.AddP70bool("ScalingMaxZ", 0);
        p.AddP70vector("GeometricTranslation", 0.0, 0.0, 0.0);
        p.AddP70vector("GeometricRotation", 0.0, 0.0, 0.0);
        p.AddP70vector("GeometricScaling", 1.0, 1.0, 1.0);
        p.AddP70double("MinDampRangeX", 0.0);
        p.AddP70double("MinDampRangeY", 0.0);
        p.AddP70double("MinDampRangeZ", 0.0);
        p.AddP70double("MaxDampRangeX", 0.0);
        p.AddP70double("MaxDampRangeY", 0.0);
        p.AddP70double("MaxDampRangeZ", 0.0);
        p.AddP70double("MinDampStrengthX", 0.0);
        p.AddP70double("MinDampStrengthY", 0.0);
        p.AddP70double("MinDampStrengthZ", 0.0);
        p.AddP70double("MaxDampStrengthX", 0.0);
        p.AddP70double("MaxDampStrengthY", 0.0);
        p.AddP70double("MaxDampStrengthZ", 0.0);
        p.AddP70double("PreferedAngleX", 0.0);
        p.AddP70double("PreferedAngleY", 0.0);
        p.AddP70double("PreferedAngleZ", 0.0);
        p.AddP70("LookAtProperty", "object", "", "");
        p.AddP70("UpVectorProperty", "object", "", "");
        p.AddP70bool("Show", 1);
        p.AddP70bool("NegativePercentShapeSupport", 1);
        p.AddP70int("DefaultAttributeIndex", -1);
        p.AddP70bool("Freeze", 0);
        p.AddP70bool("LODBox", 0);
        p.AddP70(
            "Lcl Translation", "Lcl Translation", "", "A",
            double(0), double(0), double(0)
        );
        p.AddP70(
            "Lcl Rotation", "Lcl Rotation", "", "A",
            double(0), double(0), double(0)
        );
        p.AddP70(
            "Lcl Scaling", "Lcl Scaling", "", "A",
            double(1), double(1), double(1)
        );
        p.AddP70("Visibility", "Visibility", "", "A", double(1));
        p.AddP70(
            "Visibility Inheritance", "Visibility Inheritance", "", "",
            int32_t(1)
        );
        pt.AddChild(p);
        n.AddChild(pt);
        object_nodes.push_back(n);
        total_count += count;
    }

    // Geometry / FbxMesh
    // <~~ aiMesh
    count = mScene->mNumMeshes;
    if (count) {
        n = FBX::Node("ObjectType", "Geometry");
        n.AddChild("Count", count);
        pt = FBX::Node("PropertyTemplate", "FbxMesh");
        p = FBX::Node("Properties70");
        p.AddP70color("Color", 0, 0, 0);
        p.AddP70vector("BBoxMin", 0, 0, 0);
        p.AddP70vector("BBoxMax", 0, 0, 0);
        p.AddP70bool("Primary Visibility", 1);
        p.AddP70bool("Casts Shadows", 1);
        p.AddP70bool("Receive Shadows", 1);
        pt.AddChild(p);
        n.AddChild(pt);
        object_nodes.push_back(n);
        total_count += count;
    }

    // Material / FbxSurfacePhong, FbxSurfaceLambert, FbxSurfaceMaterial
    // <~~ aiMaterial
    // basically if there's any phong material this is defined as phong,
    // and otherwise lambert.
    // More complex materials cause a bare-bones FbxSurfaceMaterial definition
    // and are treated specially, as they're not really supported by FBX.
    // TODO: support Maya's Stingray PBS material
    count = mScene->mNumMaterials;
    if (count) {
        bool has_phong = has_phong_mat(mScene);
        n = FBX::Node("ObjectType", "Material");
        n.AddChild("Count", count);
        pt = FBX::Node("PropertyTemplate");
        if (has_phong) {
            pt.AddProperty("FbxSurfacePhong");
        } else {
            pt.AddProperty("FbxSurfaceLambert");
        }
        p = FBX::Node("Properties70");
        if (has_phong) {
            p.AddP70string("ShadingModel", "Phong");
        } else {
            p.AddP70string("ShadingModel", "Lambert");
        }
        p.AddP70bool("MultiLayer", 0);
        p.AddP70colorA("EmissiveColor", 0.0, 0.0, 0.0);
        p.AddP70numberA("EmissiveFactor", 1.0);
        p.AddP70colorA("AmbientColor", 0.2, 0.2, 0.2);
        p.AddP70numberA("AmbientFactor", 1.0);
        p.AddP70colorA("DiffuseColor", 0.8, 0.8, 0.8);
        p.AddP70numberA("DiffuseFactor", 1.0);
        p.AddP70vector("Bump", 0.0, 0.0, 0.0);
        p.AddP70vector("NormalMap", 0.0, 0.0, 0.0);
        p.AddP70double("BumpFactor", 1.0);
        p.AddP70colorA("TransparentColor", 0.0, 0.0, 0.0);
        p.AddP70numberA("TransparencyFactor", 0.0);
        p.AddP70color("DisplacementColor", 0.0, 0.0, 0.0);
        p.AddP70double("DisplacementFactor", 1.0);
        p.AddP70color("VectorDisplacementColor", 0.0, 0.0, 0.0);
        p.AddP70double("VectorDisplacementFactor", 1.0);
        if (has_phong) {
            p.AddP70colorA("SpecularColor", 0.2, 0.2, 0.2);
            p.AddP70numberA("SpecularFactor", 1.0);
            p.AddP70numberA("ShininessExponent", 20.0);
            p.AddP70colorA("ReflectionColor", 0.0, 0.0, 0.0);
            p.AddP70numberA("ReflectionFactor", 1.0);
        }
        pt.AddChild(p);
        n.AddChild(pt);
        object_nodes.push_back(n);
        total_count += count;
    }

    // Video / FbxVideo
    // one for each image file.
    count = int32_t(count_images(mScene));
    if (count) {
        n = FBX::Node("ObjectType", "Video");
        n.AddChild("Count", count);
        pt = FBX::Node("PropertyTemplate", "FbxVideo");
        p = FBX::Node("Properties70");
        p.AddP70bool("ImageSequence", 0);
        p.AddP70int("ImageSequenceOffset", 0);
        p.AddP70double("FrameRate", 0.0);
        p.AddP70int("LastFrame", 0);
        p.AddP70int("Width", 0);
        p.AddP70int("Height", 0);
        p.AddP70("Path", "KString", "XRefUrl", "", "");
        p.AddP70int("StartFrame", 0);
        p.AddP70int("StopFrame", 0);
        p.AddP70double("PlaySpeed", 0.0);
        p.AddP70time("Offset", 0);
        p.AddP70enum("InterlaceMode", 0);
        p.AddP70bool("FreeRunning", 0);
        p.AddP70bool("Loop", 0);
        p.AddP70enum("AccessMode", 0);
        pt.AddChild(p);
        n.AddChild(pt);
        object_nodes.push_back(n);
        total_count += count;
    }

    // Texture / FbxFileTexture
    // <~~ aiTexture
    count = int32_t(count_textures(mScene));
    if (count) {
        n = FBX::Node("ObjectType", "Texture");
        n.AddChild("Count", count);
        pt = FBX::Node("PropertyTemplate", "FbxFileTexture");
        p = FBX::Node("Properties70");
        p.AddP70enum("TextureTypeUse", 0);
        p.AddP70numberA("Texture alpha", 1.0);
        p.AddP70enum("CurrentMappingType", 0);
        p.AddP70enum("WrapModeU", 0);
        p.AddP70enum("WrapModeV", 0);
        p.AddP70bool("UVSwap", 0);
        p.AddP70bool("PremultiplyAlpha", 1);
        p.AddP70vectorA("Translation", 0.0, 0.0, 0.0);
        p.AddP70vectorA("Rotation", 0.0, 0.0, 0.0);
        p.AddP70vectorA("Scaling", 1.0, 1.0, 1.0);
        p.AddP70vector("TextureRotationPivot", 0.0, 0.0, 0.0);
        p.AddP70vector("TextureScalingPivot", 0.0, 0.0, 0.0);
        p.AddP70enum("CurrentTextureBlendMode", 1);
        p.AddP70string("UVSet", "default");
        p.AddP70bool("UseMaterial", 0);
        p.AddP70bool("UseMipMap", 0);
        pt.AddChild(p);
        n.AddChild(pt);
        object_nodes.push_back(n);
        total_count += count;
    }

    // AnimationCurveNode / FbxAnimCurveNode
    count = mScene->mNumAnimations * 3;
    if (count) {
        n = FBX::Node("ObjectType", "AnimationCurveNode");
        n.AddChild("Count", count);
        pt = FBX::Node("PropertyTemplate", "FbxAnimCurveNode");
        p = FBX::Node("Properties70");
        p.AddP70("d", "Compound", "", "");
        pt.AddChild(p);
        n.AddChild(pt);
        object_nodes.push_back(n);
        total_count += count;
    }

    // AnimationCurve / FbxAnimCurve
    count = mScene->mNumAnimations * 9;
    if (count) {
        n = FBX::Node("ObjectType", "AnimationCurve");
        n.AddChild("Count", count);
        object_nodes.push_back(n);
        total_count += count;
    }

    // Pose
    count = 0;
    for (size_t i = 0; i < mScene->mNumMeshes; ++i) {
        aiMesh* mesh = mScene->mMeshes[i];
        if (mesh->HasBones()) { ++count; }
    }
    if (count) {
        n = FBX::Node("ObjectType", "Pose");
        n.AddChild("Count", count);
        object_nodes.push_back(n);
        total_count += count;
    }

    // Deformer
    count = int32_t(count_deformers(mScene));
    if (count) {
        n = FBX::Node("ObjectType", "Deformer");
        n.AddChild("Count", count);
        object_nodes.push_back(n);
        total_count += count;
    }

    // (template)
    count = 0;<--- Assignment 'count=0', assigned value is 0
    if (count) {<--- Condition 'count' is always false
        n = FBX::Node("ObjectType", "");
        n.AddChild("Count", count);
        pt = FBX::Node("PropertyTemplate", "");
        p = FBX::Node("Properties70");
        pt.AddChild(p);
        n.AddChild(pt);
        object_nodes.push_back(n);
        total_count += count;
    }

    // now write it all
    FBX::Node defs("Definitions");
    defs.AddChild("Version", int32_t(100));
    defs.AddChild("Count", int32_t(total_count));
    for (auto &n : object_nodes) { defs.AddChild(n); }<--- Shadow variable
    defs.Dump(outfile, binary, 0);
}


// -------------------------------------------------------------------
// some internal helper functions used for writing the objects section
// (which holds the actual data)
// -------------------------------------------------------------------

aiNode* get_node_for_mesh(unsigned int meshIndex, aiNode* node)
{
    for (size_t i = 0; i < node->mNumMeshes; ++i) {
        if (node->mMeshes[i] == meshIndex) {
            return node;
        }
    }
    for (size_t i = 0; i < node->mNumChildren; ++i) {
        aiNode* ret = get_node_for_mesh(meshIndex, node->mChildren[i]);
        if (ret) { return ret; }
    }
    return nullptr;
}

aiMatrix4x4 get_world_transform(const aiNode* node, const aiScene* scene)
{
    std::vector<const aiNode*> node_chain;
    while (node != scene->mRootNode) {
        node_chain.push_back(node);
        node = node->mParent;
    }
    aiMatrix4x4 transform;
    for (auto n = node_chain.rbegin(); n != node_chain.rend(); ++n) {
        transform *= (*n)->mTransformation;
    }
    return transform;
}

int64_t to_ktime(double ticks, const aiAnimation* anim) {
    if (anim->mTicksPerSecond <= 0) {
        return static_cast<int64_t>(ticks) * FBX::SECOND;
    }
    return (static_cast<int64_t>(ticks) / static_cast<int64_t>(anim->mTicksPerSecond)) * FBX::SECOND;
}

int64_t to_ktime(double time) {
    return (static_cast<int64_t>(time * FBX::SECOND));
}

void FBXExporter::WriteObjects ()
{
    if (!binary) {
        WriteAsciiSectionHeader("Object properties");
    }
    // numbers should match those given in definitions! make sure to check
    StreamWriterLE outstream(outfile);
    FBX::Node object_node("Objects");
    int indent = 0;
    object_node.Begin(outstream, binary, indent);
    object_node.EndProperties(outstream, binary, indent);
    object_node.BeginChildren(outstream, binary, indent);

    bool bJoinIdenticalVertices = mProperties->GetPropertyBool("bJoinIdenticalVertices", true);
    std::vector<std::vector<int32_t>> vVertexIndice;//save vertex_indices as it is needed later

    // geometry (aiMesh)
    mesh_uids.clear();
    indent = 1;
    for (size_t mi = 0; mi < mScene->mNumMeshes; ++mi) {
        // it's all about this mesh
        aiMesh* m = mScene->mMeshes[mi];

        // start the node record
        FBX::Node n("Geometry");<--- Shadowed declaration
        int64_t uid = generate_uid();
        mesh_uids.push_back(uid);
        n.AddProperty(uid);
        n.AddProperty(FBX::SEPARATOR + "Geometry");
        n.AddProperty("Mesh");
        n.Begin(outstream, binary, indent);
        n.DumpProperties(outstream, binary, indent);
        n.EndProperties(outstream, binary, indent);
        n.BeginChildren(outstream, binary, indent);
        indent = 2;

        // output vertex data - each vertex should be unique (probably)
        std::vector<double> flattened_vertices;
        // index of original vertex in vertex data vector
        std::vector<int32_t> vertex_indices;
        // map of vertex value to its index in the data vector
        std::map<aiVector3D,size_t> index_by_vertex_value;
        if(bJoinIdenticalVertices){
            int32_t index = 0;
            for (size_t vi = 0; vi < m->mNumVertices; ++vi) {
                aiVector3D vtx = m->mVertices[vi];
                auto elem = index_by_vertex_value.find(vtx);
                if (elem == index_by_vertex_value.end()) {
                    vertex_indices.push_back(index);
                    index_by_vertex_value[vtx] = index;
                    flattened_vertices.push_back(vtx[0]);
                    flattened_vertices.push_back(vtx[1]);
                    flattened_vertices.push_back(vtx[2]);
                    ++index;
                } else {
                    vertex_indices.push_back(int32_t(elem->second));
                }
            }
        }
        else { // do not join vertex, respect the export flag
            vertex_indices.resize(m->mNumVertices);
            std::iota(vertex_indices.begin(), vertex_indices.end(), 0);
            for(unsigned int v = 0; v < m->mNumVertices; ++ v) {
                aiVector3D vtx = m->mVertices[v];
                flattened_vertices.push_back(vtx.x);
                flattened_vertices.push_back(vtx.y);
                flattened_vertices.push_back(vtx.z);
            }
        }
        vVertexIndice.push_back(vertex_indices);

        FBX::Node::WritePropertyNode(
            "Vertices", flattened_vertices, outstream, binary, indent
        );

        // output polygon data as a flattened array of vertex indices.
        // the last vertex index of each polygon is negated and - 1
        std::vector<int32_t> polygon_data;
        for (size_t fi = 0; fi < m->mNumFaces; ++fi) {
            const aiFace &f = m->mFaces[fi];
            for (size_t pvi = 0; pvi < f.mNumIndices - 1; ++pvi) {
                polygon_data.push_back(vertex_indices[f.mIndices[pvi]]);
            }
            polygon_data.push_back(
                -1 - vertex_indices[f.mIndices[f.mNumIndices-1]]
            );
        }
        FBX::Node::WritePropertyNode(
            "PolygonVertexIndex", polygon_data, outstream, binary, indent
        );

        // here could be edges but they're insane.
        // it's optional anyway, so let's ignore it.

        FBX::Node::WritePropertyNode(
            "GeometryVersion", int32_t(124), outstream, binary, indent
        );

        // normals, if any
        if (m->HasNormals()) {
            FBX::Node normals("LayerElementNormal", int32_t(0));
            normals.Begin(outstream, binary, indent);
            normals.DumpProperties(outstream, binary, indent);
            normals.EndProperties(outstream, binary, indent);
            normals.BeginChildren(outstream, binary, indent);
            indent = 3;
            FBX::Node::WritePropertyNode(
                "Version", int32_t(101), outstream, binary, indent
            );
            FBX::Node::WritePropertyNode(
                "Name", "", outstream, binary, indent
            );
            FBX::Node::WritePropertyNode(
                "MappingInformationType", "ByPolygonVertex",
                outstream, binary, indent
            );
            // TODO: vertex-normals or indexed normals when appropriate
            FBX::Node::WritePropertyNode(
                "ReferenceInformationType", "Direct",
                outstream, binary, indent
            );
            std::vector<double> normal_data;
            normal_data.reserve(3 * polygon_data.size());
            for (size_t fi = 0; fi < m->mNumFaces; ++fi) {
                const aiFace &f = m->mFaces[fi];
                for (size_t pvi = 0; pvi < f.mNumIndices; ++pvi) {
                    const aiVector3D &n = m->mNormals[f.mIndices[pvi]];<--- Shadow variable
                    normal_data.push_back(n.x);
                    normal_data.push_back(n.y);
                    normal_data.push_back(n.z);
                }
            }
            FBX::Node::WritePropertyNode(
                "Normals", normal_data, outstream, binary, indent
            );
            // note: version 102 has a NormalsW also... not sure what it is,
            // so we can stick with version 101 for now.
            indent = 2;
            normals.End(outstream, binary, indent, true);
        }

        // colors, if any
        // TODO only one color channel currently
        const int32_t colorChannelIndex = 0;
        if (m->HasVertexColors(colorChannelIndex)) {
            FBX::Node vertexcolors("LayerElementColor", int32_t(colorChannelIndex));
            vertexcolors.Begin(outstream, binary, indent);
            vertexcolors.DumpProperties(outstream, binary, indent);
            vertexcolors.EndProperties(outstream, binary, indent);
            vertexcolors.BeginChildren(outstream, binary, indent);
            indent = 3;
            FBX::Node::WritePropertyNode(
                "Version", int32_t(101), outstream, binary, indent
            );
            char layerName[8];
            sprintf(layerName, "COLOR_%d", colorChannelIndex);
            FBX::Node::WritePropertyNode(
                "Name", (const char*)layerName, outstream, binary, indent
            );
            FBX::Node::WritePropertyNode(
                "MappingInformationType", "ByPolygonVertex",
                outstream, binary, indent
            );
            FBX::Node::WritePropertyNode(
                "ReferenceInformationType", "Direct",
                outstream, binary, indent
            );
            std::vector<double> color_data;
            color_data.reserve(4 * polygon_data.size());
            for (size_t fi = 0; fi < m->mNumFaces; ++fi) {
                const aiFace &f = m->mFaces[fi];
                for (size_t pvi = 0; pvi < f.mNumIndices; ++pvi) {
                    const aiColor4D &c = m->mColors[colorChannelIndex][f.mIndices[pvi]];
                    color_data.push_back(c.r);
                    color_data.push_back(c.g);
                    color_data.push_back(c.b);
                    color_data.push_back(c.a);
                }
            }
            FBX::Node::WritePropertyNode(
                "Colors", color_data, outstream, binary, indent
            );
            indent = 2;
            vertexcolors.End(outstream, binary, indent, true);
        }
        
        // uvs, if any
        for (size_t uvi = 0; uvi < m->GetNumUVChannels(); ++uvi) {
            if (m->mNumUVComponents[uvi] > 2) {
                // FBX only supports 2-channel UV maps...
                // or at least i'm not sure how to indicate a different number
                std::stringstream err;
                err << "Only 2-channel UV maps supported by FBX,";
                err << " but mesh " << mi;
                if (m->mName.length) {
                    err << " (" << m->mName.C_Str() << ")";
                }
                err << " UV map " << uvi;
                err << " has " << m->mNumUVComponents[uvi];
                err << " components! Data will be preserved,";
                err << " but may be incorrectly interpreted on load.";
                ASSIMP_LOG_WARN(err.str());
            }
            FBX::Node uv("LayerElementUV", int32_t(uvi));<--- Shadowed declaration
            uv.Begin(outstream, binary, indent);
            uv.DumpProperties(outstream, binary, indent);
            uv.EndProperties(outstream, binary, indent);
            uv.BeginChildren(outstream, binary, indent);
            indent = 3;
            FBX::Node::WritePropertyNode(
                "Version", int32_t(101), outstream, binary, indent
            );
            // it doesn't seem like assimp keeps the uv map name,
            // so just leave it blank.
            FBX::Node::WritePropertyNode(
                "Name", "", outstream, binary, indent
            );
            FBX::Node::WritePropertyNode(
                "MappingInformationType", "ByPolygonVertex",
                outstream, binary, indent
            );
            FBX::Node::WritePropertyNode(
                "ReferenceInformationType", "IndexToDirect",
                outstream, binary, indent
            );

            std::vector<double> uv_data;
            std::vector<int32_t> uv_indices;
            std::map<aiVector3D,int32_t> index_by_uv;
            int32_t index = 0;
            for (size_t fi = 0; fi < m->mNumFaces; ++fi) {
                const aiFace &f = m->mFaces[fi];
                for (size_t pvi = 0; pvi < f.mNumIndices; ++pvi) {
                    const aiVector3D &uv =<--- Shadow variable
                        m->mTextureCoords[uvi][f.mIndices[pvi]];
                    auto elem = index_by_uv.find(uv);
                    if (elem == index_by_uv.end()) {
                        index_by_uv[uv] = index;
                        uv_indices.push_back(index);
                        for (unsigned int x = 0; x < m->mNumUVComponents[uvi]; ++x) {
                            uv_data.push_back(uv[x]);
                        }
                        ++index;
                    } else {
                        uv_indices.push_back(elem->second);
                    }
                }
            }
            FBX::Node::WritePropertyNode(
                "UV", uv_data, outstream, binary, indent
            );
            FBX::Node::WritePropertyNode(
                "UVIndex", uv_indices, outstream, binary, indent
            );
            indent = 2;
            uv.End(outstream, binary, indent, true);
        }

        // i'm not really sure why this material section exists,
        // as the material is linked via "Connections".
        // it seems to always have the same "0" value.
        FBX::Node mat("LayerElementMaterial", int32_t(0));
        mat.AddChild("Version", int32_t(101));
        mat.AddChild("Name", "");
        mat.AddChild("MappingInformationType", "AllSame");
        mat.AddChild("ReferenceInformationType", "IndexToDirect");
        std::vector<int32_t> mat_indices = {0};
        mat.AddChild("Materials", mat_indices);
        mat.Dump(outstream, binary, indent);

        // finally we have the layer specifications,
        // which select the normals / UV set / etc to use.
        // TODO: handle multiple uv sets correctly?
        FBX::Node layer("Layer", int32_t(0));
        layer.AddChild("Version", int32_t(100));
        FBX::Node le("LayerElement");
        le.AddChild("Type", "LayerElementNormal");
        le.AddChild("TypedIndex", int32_t(0));
        layer.AddChild(le);
        // TODO only 1 color channel currently
        le = FBX::Node("LayerElement");
        le.AddChild("Type", "LayerElementColor");
        le.AddChild("TypedIndex", int32_t(0));
        layer.AddChild(le);
        le = FBX::Node("LayerElement");
        le.AddChild("Type", "LayerElementMaterial");
        le.AddChild("TypedIndex", int32_t(0));
        layer.AddChild(le);
        le = FBX::Node("LayerElement");
        le.AddChild("Type", "LayerElementUV");
        le.AddChild("TypedIndex", int32_t(0));
        layer.AddChild(le);
        layer.Dump(outstream, binary, indent);

        for(unsigned int lr = 1; lr < m->GetNumUVChannels(); ++ lr)
        {
            FBX::Node layerExtra("Layer", int32_t(lr));
            layerExtra.AddChild("Version", int32_t(100));
            FBX::Node leExtra("LayerElement");
            leExtra.AddChild("Type", "LayerElementUV");
            leExtra.AddChild("TypedIndex", int32_t(lr));
            layerExtra.AddChild(leExtra);
            layerExtra.Dump(outstream, binary, indent);
        }
        // finish the node record
        indent = 1;
        n.End(outstream, binary, indent, true);
    }

    // aiMaterial
    material_uids.clear();
    for (size_t i = 0; i < mScene->mNumMaterials; ++i) {
        // it's all about this material
        aiMaterial* m = mScene->mMaterials[i];

        // these are used to receive material data
        float f; aiColor3D c;

        // start the node record
        FBX::Node n("Material");

        int64_t uid = generate_uid();
        material_uids.push_back(uid);
        n.AddProperty(uid);

        aiString name;
        m->Get(AI_MATKEY_NAME, name);
        n.AddProperty(name.C_Str() + FBX::SEPARATOR + "Material");

        n.AddProperty("");

        n.AddChild("Version", int32_t(102));
        f = 0;
        m->Get(AI_MATKEY_SHININESS, f);
        bool phong = (f > 0);
        if (phong) {
            n.AddChild("ShadingModel", "phong");
        } else {
            n.AddChild("ShadingModel", "lambert");
        }
        n.AddChild("MultiLayer", int32_t(0));

        FBX::Node p("Properties70");

        // materials exported using the FBX SDK have two sets of fields.
        // there are the properties specified in the PropertyTemplate,
        // which are those supported by the modernFBX SDK,
        // and an extra set of properties with simpler names.
        // The extra properties are a legacy material system from pre-2009.
        //
        // In the modern system, each property has "color" and "factor".
        // Generally the interpretation of these seems to be
        // that the colour is multiplied by the factor before use,
        // but this is not always clear-cut.
        //
        // Usually assimp only stores the colour,
        // so we can just leave the factors at the default "1.0".

        // first we can export the "standard" properties
        if (m->Get(AI_MATKEY_COLOR_AMBIENT, c) == aiReturn_SUCCESS) {
            p.AddP70colorA("AmbientColor", c.r, c.g, c.b);
            //p.AddP70numberA("AmbientFactor", 1.0);
        }
        if (m->Get(AI_MATKEY_COLOR_DIFFUSE, c) == aiReturn_SUCCESS) {
            p.AddP70colorA("DiffuseColor", c.r, c.g, c.b);
            //p.AddP70numberA("DiffuseFactor", 1.0);
        }
        if (m->Get(AI_MATKEY_COLOR_TRANSPARENT, c) == aiReturn_SUCCESS) {
            // "TransparentColor" / "TransparencyFactor"...
            // thanks FBX, for your insightful interpretation of consistency
            p.AddP70colorA("TransparentColor", c.r, c.g, c.b);
            // TransparencyFactor defaults to 0.0, so set it to 1.0.
            // note: Maya always sets this to 1.0,
            // so we can't use it sensibly as "Opacity".
            // In stead we rely on the legacy "Opacity" value, below.
            // Blender also relies on "Opacity" not "TransparencyFactor",
            // probably for a similar reason.
            p.AddP70numberA("TransparencyFactor", 1.0);
        }
        if (m->Get(AI_MATKEY_COLOR_REFLECTIVE, c) == aiReturn_SUCCESS) {
            p.AddP70colorA("ReflectionColor", c.r, c.g, c.b);
        }
        if (m->Get(AI_MATKEY_REFLECTIVITY, f) == aiReturn_SUCCESS) {
            p.AddP70numberA("ReflectionFactor", f);
        }
        if (phong) {
            if (m->Get(AI_MATKEY_COLOR_SPECULAR, c) == aiReturn_SUCCESS) {
                p.AddP70colorA("SpecularColor", c.r, c.g, c.b);
            }
            if (m->Get(AI_MATKEY_SHININESS_STRENGTH, f) == aiReturn_SUCCESS) {
                p.AddP70numberA("ShininessFactor", f);
            }
            if (m->Get(AI_MATKEY_SHININESS, f) == aiReturn_SUCCESS) {
                p.AddP70numberA("ShininessExponent", f);
            }
            if (m->Get(AI_MATKEY_REFLECTIVITY, f) == aiReturn_SUCCESS) {
                p.AddP70numberA("ReflectionFactor", f);
            }
        }

        // Now the legacy system.
        // For safety let's include it.
        // thrse values don't exist in the property template,
        // and usually are completely ignored when loading.
        // One notable exception is the "Opacity" property,
        // which Blender uses as (1.0 - alpha).
        c.r = 0.0f; c.g = 0.0f; c.b = 0.0f;
        m->Get(AI_MATKEY_COLOR_EMISSIVE, c);
        p.AddP70vector("Emissive", c.r, c.g, c.b);
        c.r = 0.2f; c.g = 0.2f; c.b = 0.2f;
        m->Get(AI_MATKEY_COLOR_AMBIENT, c);
        p.AddP70vector("Ambient", c.r, c.g, c.b);
        c.r = 0.8f; c.g = 0.8f; c.b = 0.8f;
        m->Get(AI_MATKEY_COLOR_DIFFUSE, c);
        p.AddP70vector("Diffuse", c.r, c.g, c.b);
        // The FBX SDK determines "Opacity" from transparency colour (RGB)
        // and factor (F) as: O = (1.0 - F * ((R + G + B) / 3)).
        // However we actually have an opacity value,
        // so we should take it from AI_MATKEY_OPACITY if possible.
        // It might make more sense to use TransparencyFactor,
        // but Blender actually loads "Opacity" correctly, so let's use it.
        f = 1.0f;
        if (m->Get(AI_MATKEY_COLOR_TRANSPARENT, c) == aiReturn_SUCCESS) {
            f = 1.0f - ((c.r + c.g + c.b) / 3.0f);
        }
        m->Get(AI_MATKEY_OPACITY, f);
        p.AddP70double("Opacity", f);
        if (phong) {
            // specular color is multiplied by shininess_strength
            c.r = 0.2f; c.g = 0.2f; c.b = 0.2f;
            m->Get(AI_MATKEY_COLOR_SPECULAR, c);
            f = 1.0f;
            m->Get(AI_MATKEY_SHININESS_STRENGTH, f);
            p.AddP70vector("Specular", f*c.r, f*c.g, f*c.b);
            f = 20.0f;
            m->Get(AI_MATKEY_SHININESS, f);
            p.AddP70double("Shininess", f);
            // Legacy "Reflectivity" is F*F*((R+G+B)/3),
            // where F is the proportion of light reflected (AKA reflectivity),
            // and RGB is the reflective colour of the material.
            // No idea why, but we might as well set it the same way.
            f = 0.0f;
            m->Get(AI_MATKEY_REFLECTIVITY, f);
            c.r = 1.0f, c.g = 1.0f, c.b = 1.0f;
            m->Get(AI_MATKEY_COLOR_REFLECTIVE, c);
            p.AddP70double("Reflectivity", f*f*((c.r+c.g+c.b)/3.0));
        }

        n.AddChild(p);

        n.Dump(outstream, binary, indent);
    }

    // we need to look up all the images we're using,
    // so we can generate uids, and eliminate duplicates.
    std::map<std::string, int64_t> uid_by_image;
    for (size_t i = 0; i < mScene->mNumMaterials; ++i) {
        aiString texpath;
        aiMaterial* mat = mScene->mMaterials[i];
        for (
            size_t tt = aiTextureType_DIFFUSE;
            tt < aiTextureType_UNKNOWN;
            ++tt
        ){
            const aiTextureType textype = static_cast<aiTextureType>(tt);
            const size_t texcount = mat->GetTextureCount(textype);
            for (size_t j = 0; j < texcount; ++j) {
                mat->GetTexture(textype, (unsigned int)j, &texpath);
                const std::string texstring = texpath.C_Str();
                auto elem = uid_by_image.find(texstring);
                if (elem == uid_by_image.end()) {
                    uid_by_image[texstring] = generate_uid();
                }
            }
        }
    }

    // FbxVideo - stores images used by textures.
    for (const auto &it : uid_by_image) {
        FBX::Node n("Video");
        const int64_t& uid = it.second;
        const std::string name = ""; // TODO: ... name???
        n.AddProperties(uid, name + FBX::SEPARATOR + "Video", "Clip");
        n.AddChild("Type", "Clip");
        FBX::Node p("Properties70");
        // TODO: get full path... relative path... etc... ugh...
        // for now just use the same path for everything,
        // and hopefully one of them will work out.
        std::string path = it.first;
        // try get embedded texture
        const aiTexture* embedded_texture = mScene->GetEmbeddedTexture(it.first.c_str());
        if (embedded_texture != nullptr) {
            // change the path (use original filename, if available. If name is empty, concatenate texture index with file extension)
            std::stringstream newPath;
            if (embedded_texture->mFilename.length > 0) {
                newPath << embedded_texture->mFilename.C_Str();
            } else if (embedded_texture->achFormatHint[0]) {
                int texture_index = std::stoi(path.substr(1, path.size() - 1));
                newPath << texture_index << "." << embedded_texture->achFormatHint;
            }
            path = newPath.str();
            // embed the texture
            size_t texture_size = static_cast<size_t>(embedded_texture->mWidth * std::max(embedded_texture->mHeight, 1u));
            if (binary) {
                // embed texture as binary data
                std::vector<uint8_t> tex_data;
                tex_data.resize(texture_size);
                memcpy(&tex_data[0], (char*)embedded_texture->pcData, texture_size);
                n.AddChild("Content", tex_data);
            } else {
                // embed texture in base64 encoding
                std::string encoded_texture = FBX::Util::EncodeBase64((char*)embedded_texture->pcData, texture_size);
                n.AddChild("Content", encoded_texture);
            }
        }
        p.AddP70("Path", "KString", "XRefUrl", "", path);
        n.AddChild(p);
        n.AddChild("UseMipMap", int32_t(0));
        n.AddChild("Filename", path);
        n.AddChild("RelativeFilename", path);
        n.Dump(outstream, binary, indent);
    }

    // Textures
    // referenced by material_index/texture_type pairs.
    std::map<std::pair<size_t,size_t>,int64_t> texture_uids;<--- Unused variable: texture_uids
    const std::map<aiTextureType,std::string> prop_name_by_tt = {
        {aiTextureType_DIFFUSE,      "DiffuseColor"},
        {aiTextureType_SPECULAR,     "SpecularColor"},
        {aiTextureType_AMBIENT,      "AmbientColor"},
        {aiTextureType_EMISSIVE,     "EmissiveColor"},
        {aiTextureType_HEIGHT,       "Bump"},
        {aiTextureType_NORMALS,      "NormalMap"},
        {aiTextureType_SHININESS,    "ShininessExponent"},
        {aiTextureType_OPACITY,      "TransparentColor"},
        {aiTextureType_DISPLACEMENT, "DisplacementColor"},
        //{aiTextureType_LIGHTMAP, "???"},
        {aiTextureType_REFLECTION,   "ReflectionColor"}
        //{aiTextureType_UNKNOWN, ""}
    };
    for (size_t i = 0; i < mScene->mNumMaterials; ++i) {
        // textures are attached to materials
        aiMaterial* mat = mScene->mMaterials[i];
        int64_t material_uid = material_uids[i];

        for (
            size_t j = aiTextureType_DIFFUSE;
            j < aiTextureType_UNKNOWN;
            ++j
        ) {
            const aiTextureType tt = static_cast<aiTextureType>(j);
            size_t n = mat->GetTextureCount(tt);

            if (n < 1) { // no texture of this type
                continue;
            }

            if (n > 1) {
                // TODO: multilayer textures
                std::stringstream err;
                err << "Multilayer textures not supported (for now),";
                err << " skipping texture type " << j;
                err << " of material " << i;
                ASSIMP_LOG_WARN(err.str());
            }

            // get image path for this (single-image) texture
            aiString tpath;
            if (mat->GetTexture(tt, 0, &tpath) != aiReturn_SUCCESS) {
                std::stringstream err;
                err << "Failed to get texture 0 for texture of type " << tt;
                err << " on material " << i;
                err << ", however GetTextureCount returned 1.";
                throw DeadlyExportError(err.str());
            }
            const std::string texture_path(tpath.C_Str());

            // get connected image uid
            auto elem = uid_by_image.find(texture_path);
            if (elem == uid_by_image.end()) {
                // this should never happen
                std::stringstream err;
                err << "Failed to find video element for texture with path";
                err << " \"" << texture_path << "\"";
                err << ", type " << j << ", material " << i;
                throw DeadlyExportError(err.str());
            }
            const int64_t image_uid = elem->second;

            // get the name of the material property to connect to
            auto elem2 = prop_name_by_tt.find(tt);
            if (elem2 == prop_name_by_tt.end()) {
                // don't know how to handle this type of texture,
                // so skip it.
                std::stringstream err;
                err << "Not sure how to handle texture of type " << j;
                err << " on material " << i;
                err << ", skipping...";
                ASSIMP_LOG_WARN(err.str());
                continue;
            }
            const std::string& prop_name = elem2->second;

            // generate a uid for this texture
            const int64_t texture_uid = generate_uid();

            // link the texture to the material
            connections.emplace_back(
                "C", "OP", texture_uid, material_uid, prop_name
            );

            // link the image data to the texture
            connections.emplace_back("C", "OO", image_uid, texture_uid);

            // now write the actual texture node
            FBX::Node tnode("Texture");
            // TODO: some way to determine texture name?
            const std::string texture_name = "" + FBX::SEPARATOR + "Texture";
            tnode.AddProperties(texture_uid, texture_name, "");
            // there really doesn't seem to be a better type than this:
            tnode.AddChild("Type", "TextureVideoClip");
            tnode.AddChild("Version", int32_t(202));
            tnode.AddChild("TextureName", texture_name);
            FBX::Node p("Properties70");
            p.AddP70enum("CurrentTextureBlendMode", 0); // TODO: verify
            //p.AddP70string("UVSet", ""); // TODO: how should this work?
            p.AddP70bool("UseMaterial", 1);
            tnode.AddChild(p);
            // can't easily detrmine which texture path will be correct,
            // so just store what we have in every field.
            // these being incorrect is a common problem with FBX anyway.
            tnode.AddChild("FileName", texture_path);
            tnode.AddChild("RelativeFilename", texture_path);
            tnode.AddChild("ModelUVTranslation", double(0.0), double(0.0));
            tnode.AddChild("ModelUVScaling", double(1.0), double(1.0));
            tnode.AddChild("Texture_Alpha_Source", "None");
            tnode.AddChild(
                "Cropping", int32_t(0), int32_t(0), int32_t(0), int32_t(0)
            );
            tnode.Dump(outstream, binary, indent);
        }
    }

    // bones.
    //
    // output structure:
    // subset of node hierarchy that are "skeleton",
    // i.e. do not have meshes but only bones.
    // but.. i'm not sure how anyone could guarantee that...
    //
    // input...
    // well, for each mesh it has "bones",
    // and the bone names correspond to nodes.
    // of course we also need the parent nodes,
    // as they give some of the transform........
    //
    // well. we can assume a sane input, i suppose.
    //
    // so input is the bone node hierarchy,
    // with an extra thing for the transformation of the MESH in BONE space.
    //
    // output is a set of bone nodes,
    // a "bindpose" which indicates the default local transform of all bones,
    // and a set of "deformers".
    // each deformer is parented to a mesh geometry,
    // and has one or more "subdeformer"s as children.
    // each subdeformer has one bone node as a child,
    // and represents the influence of that bone on the grandparent mesh.
    // the subdeformer has a list of indices, and weights,
    // with indices specifying vertex indices,
    // and weights specifying the corresponding influence of this bone.
    // it also has Transform and TransformLink elements,
    // specifying the transform of the MESH in BONE space,
    // and the transformation of the BONE in WORLD space,
    // likely in the bindpose.
    //
    // the input bone structure is different but similar,
    // storing the number of weights for this bone,
    // and an array of (vertex index, weight) pairs.
    //
    // one sticky point is that the number of vertices may not match,
    // because assimp splits vertices by normal, uv, etc.

    // functor for aiNode sorting
    struct SortNodeByName
    {
        bool operator()(const aiNode *lhs, const aiNode *rhs) const
        {
            return strcmp(lhs->mName.C_Str(), rhs->mName.C_Str()) < 0;
        }
    };

    // first we should mark the skeleton for each mesh.
    // the skeleton must include not only the aiBones,
    // but also all their parent nodes.
    // anything that affects the position of any bone node must be included.
    // Use SorNodeByName to make sure the exported result will be the same across all systems
    // Otherwise the aiNodes of the skeleton would be sorted based on the pointer address, which isn't consistent
    std::vector<std::set<const aiNode*, SortNodeByName>> skeleton_by_mesh(mScene->mNumMeshes);
    // at the same time we can build a list of all the skeleton nodes,
    // which will be used later to mark them as type "limbNode".
    std::unordered_set<const aiNode*> limbnodes;
    
    //actual bone nodes in fbx, without parenting-up
    std::unordered_set<std::string> setAllBoneNamesInScene;
    for(unsigned int m = 0; m < mScene->mNumMeshes; ++ m)
    {
        aiMesh* pMesh = mScene->mMeshes[m];
        for(unsigned int b = 0; b < pMesh->mNumBones; ++ b)
            setAllBoneNamesInScene.insert(pMesh->mBones[b]->mName.data);
    }
    aiMatrix4x4 mxTransIdentity;
    
    // and a map of nodes by bone name, as finding them is annoying.
    std::map<std::string,aiNode*> node_by_bone;
    for (size_t mi = 0; mi < mScene->mNumMeshes; ++mi) {
        const aiMesh* m = mScene->mMeshes[mi];
        std::set<const aiNode*, SortNodeByName> skeleton;
        for (size_t bi =0; bi < m->mNumBones; ++bi) {
            const aiBone* b = m->mBones[bi];
            const std::string name(b->mName.C_Str());
            auto elem = node_by_bone.find(name);
            aiNode* n;
            if (elem != node_by_bone.end()) {
                n = elem->second;
            } else {
                n = mScene->mRootNode->FindNode(b->mName);
                if (!n) {
                    // this should never happen
                    std::stringstream err;
                    err << "Failed to find node for bone: \"" << name << "\"";
                    throw DeadlyExportError(err.str());
                }
                node_by_bone[name] = n;
                limbnodes.insert(n);
            }
            skeleton.insert(n);
            // mark all parent nodes as skeleton as well,
            // up until we find the root node,
            // or else the node containing the mesh,
            // or else the parent of a node containig the mesh.
            for (
                const aiNode* parent = n->mParent;
                parent && parent != mScene->mRootNode;
                parent = parent->mParent
            ) {
                // if we've already done this node we can skip it all
                if (skeleton.count(parent)) {
                    break;
                }
                // ignore fbx transform nodes as these will be collapsed later
                // TODO: cache this by aiNode*
                const std::string node_name(parent->mName.C_Str());
                if (node_name.find(MAGIC_NODE_TAG) != std::string::npos) {
                    continue;
                }
                //not a bone in scene && no effect in transform
                if(setAllBoneNamesInScene.find(node_name)==setAllBoneNamesInScene.end()
                   && parent->mTransformation == mxTransIdentity) {
                        continue;
                }
                // otherwise check if this is the root of the skeleton
                bool end = false;
                // is the mesh part of this node?
                for (size_t i = 0; i < parent->mNumMeshes; ++i) {
                    if (parent->mMeshes[i] == mi) {
                        end = true;
                        break;
                    }
                }
                // is the mesh in one of the children of this node?
                for (size_t j = 0; j < parent->mNumChildren; ++j) {
                    aiNode* child = parent->mChildren[j];
                    for (size_t i = 0; i < child->mNumMeshes; ++i) {
                        if (child->mMeshes[i] == mi) {
                            end = true;
                            break;
                        }
                    }
                    if (end) { break; }
                }
                
                // if it was the skeleton root we can finish here
                if (end) { break; }
            }
        }
        skeleton_by_mesh[mi] = skeleton;
    }

    // we'll need the uids for the bone nodes, so generate them now
    for (size_t i = 0; i < mScene->mNumMeshes; ++i) {
        auto &s = skeleton_by_mesh[i];
        for (const aiNode* n : s) {
            auto elem = node_uids.find(n);
            if (elem == node_uids.end()) {
                node_uids[n] = generate_uid();
            }
        }
    }

    // now, for each aiMesh, we need to export a deformer,
    // and for each aiBone a subdeformer,
    // which should have all the skinning info.
    // these will need to be connected properly to the mesh,
    // and we can do that all now.
    for (size_t mi = 0; mi < mScene->mNumMeshes; ++mi) {
        const aiMesh* m = mScene->mMeshes[mi];
        if (!m->HasBones()) {
            continue;
        }
        // make a deformer for this mesh
        int64_t deformer_uid = generate_uid();
        FBX::Node dnode("Deformer");
        dnode.AddProperties(deformer_uid, FBX::SEPARATOR + "Deformer", "Skin");
        dnode.AddChild("Version", int32_t(101));
        // "acuracy"... this is not a typo....
        dnode.AddChild("Link_DeformAcuracy", double(50));
        dnode.AddChild("SkinningType", "Linear"); // TODO: other modes?
        dnode.Dump(outstream, binary, indent);

        // connect it
        connections.emplace_back("C", "OO", deformer_uid, mesh_uids[mi]);

        //computed before
        std::vector<int32_t>& vertex_indices = vVertexIndice[mi];

        // TODO, FIXME: this won't work if anything is not in the bind pose.
        // for now if such a situation is detected, we throw an exception.
        std::set<const aiBone*> not_in_bind_pose;
        std::set<const aiNode*> no_offset_matrix;

        // first get this mesh's position in world space,
        // as we'll need it for each subdeformer.
        //
        // ...of course taking the position of the MESH doesn't make sense,
        // as it can be instanced to many nodes.
        // All we can do is assume no instancing,
        // and take the first node we find that contains the mesh.
        aiNode* mesh_node = get_node_for_mesh((unsigned int)mi, mScene->mRootNode);
        aiMatrix4x4 mesh_xform = get_world_transform(mesh_node, mScene);

        // now make a subdeformer for each bone in the skeleton
        const std::set<const aiNode*, SortNodeByName> skeleton= skeleton_by_mesh[mi];
        for (const aiNode* bone_node : skeleton) {
            // if there's a bone for this node, find it
            const aiBone* b = nullptr;
            for (size_t bi = 0; bi < m->mNumBones; ++bi) {
                // TODO: this probably should index by something else
                const std::string name(m->mBones[bi]->mName.C_Str());
                if (node_by_bone[name] == bone_node) {
                    b = m->mBones[bi];
                    break;
                }
            }
            if (!b) {
                no_offset_matrix.insert(bone_node);
            }

            // start the subdeformer node
            const int64_t subdeformer_uid = generate_uid();
            FBX::Node sdnode("Deformer");
            sdnode.AddProperties(
                subdeformer_uid, FBX::SEPARATOR + "SubDeformer", "Cluster"
            );
            sdnode.AddChild("Version", int32_t(100));
            sdnode.AddChild("UserData", "", "");

            // add indices and weights, if any
            if (b) {
                std::vector<int32_t> subdef_indices;
                std::vector<double> subdef_weights;
                int32_t last_index = -1;
                for (size_t wi = 0; wi < b->mNumWeights; ++wi) {
                    int32_t vi = vertex_indices[b->mWeights[wi].mVertexId];
                    if (vi == last_index) {
                        // only for vertices we exported to fbx
                        // TODO, FIXME: this assumes identically-located vertices
                        // will always deform in the same way.
                        // as assimp doesn't store a separate list of "positions",
                        // there's not much that can be done about this
                        // other than assuming that identical position means
                        // identical vertex.
                        continue;
                    }
                    subdef_indices.push_back(vi);
                    subdef_weights.push_back(b->mWeights[wi].mWeight);
                    last_index = vi;
                }
                // yes, "indexes"
                sdnode.AddChild("Indexes", subdef_indices);
                sdnode.AddChild("Weights", subdef_weights);
            }

            // transform is the transform of the mesh, but in bone space.
            // if the skeleton is in the bind pose,
            // we can take the inverse of the world-space bone transform
            // and multiply by the world-space transform of the mesh.
            aiMatrix4x4 bone_xform = get_world_transform(bone_node, mScene);
            aiMatrix4x4 inverse_bone_xform = bone_xform;
            inverse_bone_xform.Inverse();
            aiMatrix4x4 tr = inverse_bone_xform * mesh_xform;

            sdnode.AddChild("Transform", tr);


            sdnode.AddChild("TransformLink", bone_xform);
            // note: this means we ALWAYS rely on the mesh node transform
            // being unchanged from the time the skeleton was bound.
            // there's not really any way around this at the moment.

            // done
            sdnode.Dump(outstream, binary, indent);

            // lastly, connect to the parent deformer
            connections.emplace_back(
                "C", "OO", subdeformer_uid, deformer_uid
            );

            // we also need to connect the limb node to the subdeformer.
            connections.emplace_back(
                "C", "OO", node_uids[bone_node], subdeformer_uid
            );
        }

        // if we cannot create a valid FBX file, simply die.
        // this will both prevent unnecessary bug reports,
        // and tell the user what they can do to fix the situation
        // (i.e. export their model in the bind pose).
        if (no_offset_matrix.size() && not_in_bind_pose.size()) {
            std::stringstream err;
            err << "Not enough information to construct bind pose";
            err << " for mesh " << mi << "!";
            err << " Transform matrix for bone \"";
            err << (*not_in_bind_pose.begin())->mName.C_Str() << "\"";
            if (not_in_bind_pose.size() > 1) {
                err << " (and " << not_in_bind_pose.size() - 1 << " more)";
            }
            err << " does not match mOffsetMatrix,";
            err << " and node \"";
            err << (*no_offset_matrix.begin())->mName.C_Str() << "\"";
            if (no_offset_matrix.size() > 1) {
                err << " (and " << no_offset_matrix.size() - 1 << " more)";
            }
            err << " has no offset matrix to rely on.";
            err << " Please ensure bones are in the bind pose to export.";
            throw DeadlyExportError(err.str());
        }

    }

    // BindPose
    //
    // This is a legacy system, which should be unnecessary.
    //
    // Somehow including it slows file loading by the official FBX SDK,
    // and as it can reconstruct it from the deformers anyway,
    // this is not currently included.
    //
    // The code is kept here in case it's useful in the future,
    // but it's pretty much a hack anyway,
    // as assimp doesn't store bindpose information for full skeletons.
    //
    /*for (size_t mi = 0; mi < mScene->mNumMeshes; ++mi) {
        aiMesh* mesh = mScene->mMeshes[mi];
        if (! mesh->HasBones()) { continue; }
        int64_t bindpose_uid = generate_uid();
        FBX::Node bpnode("Pose");
        bpnode.AddProperty(bindpose_uid);
        // note: this uid is never linked or connected to anything.
        bpnode.AddProperty(FBX::SEPARATOR + "Pose"); // blank name
        bpnode.AddProperty("BindPose");

        bpnode.AddChild("Type", "BindPose");
        bpnode.AddChild("Version", int32_t(100));

        aiNode* mesh_node = get_node_for_mesh(mi, mScene->mRootNode);

        // next get the whole skeleton for this mesh.
        // we need it all to define the bindpose section.
        // the FBX SDK will complain if it's missing,
        // and also if parents of used bones don't have a subdeformer.
        // order shouldn't matter.
        std::set<aiNode*> skeleton;
        for (size_t bi = 0; bi < mesh->mNumBones; ++bi) {
            // bone node should have already been indexed
            const aiBone* b = mesh->mBones[bi];
            const std::string bone_name(b->mName.C_Str());
            aiNode* parent = node_by_bone[bone_name];
            // insert all nodes down to the root or mesh node
            while (
                parent
                && parent != mScene->mRootNode
                && parent != mesh_node
            ) {
                skeleton.insert(parent);
                parent = parent->mParent;
            }
        }

        // number of pose nodes. includes one for the mesh itself.
        bpnode.AddChild("NbPoseNodes", int32_t(1 + skeleton.size()));

        // the first pose node is always the mesh itself
        FBX::Node pose("PoseNode");
        pose.AddChild("Node", mesh_uids[mi]);
        aiMatrix4x4 mesh_node_xform = get_world_transform(mesh_node, mScene);
        pose.AddChild("Matrix", mesh_node_xform);
        bpnode.AddChild(pose);

        for (aiNode* bonenode : skeleton) {
            // does this node have a uid yet?
            int64_t node_uid;
            auto node_uid_iter = node_uids.find(bonenode);
            if (node_uid_iter != node_uids.end()) {
                node_uid = node_uid_iter->second;
            } else {
                node_uid = generate_uid();
                node_uids[bonenode] = node_uid;
            }

            // make a pose thingy
            pose = FBX::Node("PoseNode");
            pose.AddChild("Node", node_uid);
            aiMatrix4x4 node_xform = get_world_transform(bonenode, mScene);
            pose.AddChild("Matrix", node_xform);
            bpnode.AddChild(pose);
        }

        // now write it
        bpnode.Dump(outstream, binary, indent);
    }*/

    // TODO: cameras, lights

    // write nodes (i.e. model hierarchy)
    // start at root node
    WriteModelNodes(
        outstream, mScene->mRootNode, 0, limbnodes
    );

    // animations
    //
    // in FBX there are:
    // * AnimationStack - corresponds to an aiAnimation
    // * AnimationLayer - a combinable animation component
    // * AnimationCurveNode - links the property to be animated
    // * AnimationCurve - defines animation data for a single property value
    //
    // the CurveNode also provides the default value for a property,
    // such as the X, Y, Z coordinates for animatable translation.
    //
    // the Curve only specifies values for one component of the property,
    // so there will be a separate AnimationCurve for X, Y, and Z.
    //
    // Assimp has:
    // * aiAnimation - basically corresponds to an AnimationStack
    // * aiNodeAnim - defines all animation for one aiNode
    // * aiVectorKey/aiQuatKey - define the keyframe data for T/R/S
    //
    // assimp has no equivalent for AnimationLayer,
    // and these are flattened on FBX import.
    // we can assume there will be one per AnimationStack.
    //
    // the aiNodeAnim contains all animation data for a single aiNode,
    // which will correspond to three AnimationCurveNode's:
    // one each for translation, rotation and scale.
    // The data for each of these will be put in 9 AnimationCurve's,
    // T.X, T.Y, T.Z, R.X, R.Y, R.Z, etc.

    // AnimationStack / aiAnimation
    std::vector<int64_t> animation_stack_uids(mScene->mNumAnimations);
    for (size_t ai = 0; ai < mScene->mNumAnimations; ++ai) {
        int64_t animstack_uid = generate_uid();
        animation_stack_uids[ai] = animstack_uid;
        const aiAnimation* anim = mScene->mAnimations[ai];

        FBX::Node asnode("AnimationStack");
        std::string name = anim->mName.C_Str() + FBX::SEPARATOR + "AnimStack";
        asnode.AddProperties(animstack_uid, name, "");
        FBX::Node p("Properties70");
        p.AddP70time("LocalStart", 0); // assimp doesn't store this
        p.AddP70time("LocalStop", to_ktime(anim->mDuration, anim));
        p.AddP70time("ReferenceStart", 0);
        p.AddP70time("ReferenceStop", to_ktime(anim->mDuration, anim));
        asnode.AddChild(p);

        // this node absurdly always pretends it has children
        // (in this case it does, but just in case...)
        asnode.force_has_children = true;
        asnode.Dump(outstream, binary, indent);

        // note: animation stacks are not connected to anything
    }

    // AnimationLayer - one per aiAnimation
    std::vector<int64_t> animation_layer_uids(mScene->mNumAnimations);
    for (size_t ai = 0; ai < mScene->mNumAnimations; ++ai) {
        int64_t animlayer_uid = generate_uid();
        animation_layer_uids[ai] = animlayer_uid;
        FBX::Node alnode("AnimationLayer");
        alnode.AddProperties(animlayer_uid, FBX::SEPARATOR + "AnimLayer", "");

        // this node absurdly always pretends it has children
        alnode.force_has_children = true;
        alnode.Dump(outstream, binary, indent);

        // connect to the relevant animstack
        connections.emplace_back(
            "C", "OO", animlayer_uid, animation_stack_uids[ai]
        );
    }

    // AnimCurveNode - three per aiNodeAnim
    std::vector<std::vector<std::array<int64_t,3>>> curve_node_uids;
    for (size_t ai = 0; ai < mScene->mNumAnimations; ++ai) {
        const aiAnimation* anim = mScene->mAnimations[ai];
        const int64_t layer_uid = animation_layer_uids[ai];
        std::vector<std::array<int64_t,3>> nodeanim_uids;
        for (size_t nai = 0; nai < anim->mNumChannels; ++nai) {
            const aiNodeAnim* na = anim->mChannels[nai];
            // get the corresponding aiNode
            const aiNode* node = mScene->mRootNode->FindNode(na->mNodeName);
            // and its transform
            const aiMatrix4x4 node_xfm = get_world_transform(node, mScene);
            aiVector3D T, R, S;
            node_xfm.Decompose(S, R, T);

            // AnimationCurveNode uids
            std::array<int64_t,3> ids;
            ids[0] = generate_uid(); // T
            ids[1] = generate_uid(); // R
            ids[2] = generate_uid(); // S

            // translation
            WriteAnimationCurveNode(outstream,
                ids[0], "T", T, "Lcl Translation",
                layer_uid, node_uids[node]
            );

            // rotation
            WriteAnimationCurveNode(outstream,
                ids[1], "R", R, "Lcl Rotation",
                layer_uid, node_uids[node]
            );

            // scale
            WriteAnimationCurveNode(outstream,
                ids[2], "S", S, "Lcl Scale",
                layer_uid, node_uids[node]
            );

            // store the uids for later use
            nodeanim_uids.push_back(ids);
        }
        curve_node_uids.push_back(nodeanim_uids);
    }

    // AnimCurve - defines actual keyframe data.
    // there's a separate curve for every component of every vector,
    // for example a transform curvenode will have separate X/Y/Z AnimCurve's
    for (size_t ai = 0; ai < mScene->mNumAnimations; ++ai) {
        const aiAnimation* anim = mScene->mAnimations[ai];
        for (size_t nai = 0; nai < anim->mNumChannels; ++nai) {
            const aiNodeAnim* na = anim->mChannels[nai];
            // get the corresponding aiNode
            const aiNode* node = mScene->mRootNode->FindNode(na->mNodeName);
            // and its transform
            const aiMatrix4x4 node_xfm = get_world_transform(node, mScene);
            aiVector3D T, R, S;
            node_xfm.Decompose(S, R, T);
            const std::array<int64_t,3>& ids = curve_node_uids[ai][nai];

            std::vector<int64_t> times;
            std::vector<float> xval, yval, zval;

            // position/translation
            for (size_t ki = 0; ki < na->mNumPositionKeys; ++ki) {
                const aiVectorKey& k = na->mPositionKeys[ki];
                times.push_back(to_ktime(k.mTime));
                xval.push_back(k.mValue.x);
                yval.push_back(k.mValue.y);
                zval.push_back(k.mValue.z);
            }
            // one curve each for X, Y, Z
            WriteAnimationCurve(outstream, T.x, times, xval, ids[0], "d|X");
            WriteAnimationCurve(outstream, T.y, times, yval, ids[0], "d|Y");
            WriteAnimationCurve(outstream, T.z, times, zval, ids[0], "d|Z");

            // rotation
            times.clear(); xval.clear(); yval.clear(); zval.clear();
            for (size_t ki = 0; ki < na->mNumRotationKeys; ++ki) {
                const aiQuatKey& k = na->mRotationKeys[ki];
                times.push_back(to_ktime(k.mTime));
                // TODO: aiQuaternion method to convert to Euler...
                aiMatrix4x4 m(k.mValue.GetMatrix());
                aiVector3D qs, qr, qt;
                m.Decompose(qs, qr, qt);
                qr *= DEG;
                xval.push_back(qr.x);
                yval.push_back(qr.y);
                zval.push_back(qr.z);
            }
            WriteAnimationCurve(outstream, R.x, times, xval, ids[1], "d|X");
            WriteAnimationCurve(outstream, R.y, times, yval, ids[1], "d|Y");
            WriteAnimationCurve(outstream, R.z, times, zval, ids[1], "d|Z");

            // scaling/scale
            times.clear(); xval.clear(); yval.clear(); zval.clear();
            for (size_t ki = 0; ki < na->mNumScalingKeys; ++ki) {
                const aiVectorKey& k = na->mScalingKeys[ki];
                times.push_back(to_ktime(k.mTime));
                xval.push_back(k.mValue.x);
                yval.push_back(k.mValue.y);
                zval.push_back(k.mValue.z);
            }
            WriteAnimationCurve(outstream, S.x, times, xval, ids[2], "d|X");
            WriteAnimationCurve(outstream, S.y, times, yval, ids[2], "d|Y");
            WriteAnimationCurve(outstream, S.z, times, zval, ids[2], "d|Z");
        }
    }

    indent = 0;
    object_node.End(outstream, binary, indent, true);
}

// convenience map of magic node name strings to FBX properties,
// including the expected type of transform.
const std::map<std::string,std::pair<std::string,char>> transform_types = {
    {"Translation", {"Lcl Translation", 't'}},
    {"RotationOffset", {"RotationOffset", 't'}},
    {"RotationPivot", {"RotationPivot", 't'}},
    {"PreRotation", {"PreRotation", 'r'}},
    {"Rotation", {"Lcl Rotation", 'r'}},
    {"PostRotation", {"PostRotation", 'r'}},
    {"RotationPivotInverse", {"RotationPivotInverse", 'i'}},
    {"ScalingOffset", {"ScalingOffset", 't'}},
    {"ScalingPivot", {"ScalingPivot", 't'}},
    {"Scaling", {"Lcl Scaling", 's'}},
    {"ScalingPivotInverse", {"ScalingPivotInverse", 'i'}},
    {"GeometricScaling", {"GeometricScaling", 's'}},
    {"GeometricRotation", {"GeometricRotation", 'r'}},
    {"GeometricTranslation", {"GeometricTranslation", 't'}},
    {"GeometricTranslationInverse", {"GeometricTranslationInverse", 'i'}},
    {"GeometricRotationInverse", {"GeometricRotationInverse", 'i'}},
    {"GeometricScalingInverse", {"GeometricScalingInverse", 'i'}}
};

// write a single model node to the stream
void FBXExporter::WriteModelNode(
    StreamWriterLE& outstream,
    bool binary,
    const aiNode* node,
    int64_t node_uid,
    const std::string& type,
    const std::vector<std::pair<std::string,aiVector3D>>& transform_chain,
    TransformInheritance inherit_type
){
    const aiVector3D zero = {0, 0, 0};
    const aiVector3D one = {1, 1, 1};
    FBX::Node m("Model");
    std::string name = node->mName.C_Str() + FBX::SEPARATOR + "Model";<--- Shadowed declaration
    m.AddProperties(node_uid, name, type);
    m.AddChild("Version", int32_t(232));
    FBX::Node p("Properties70");
    p.AddP70bool("RotationActive", 1);
    p.AddP70int("DefaultAttributeIndex", 0);
    p.AddP70enum("InheritType", inherit_type);
    if (transform_chain.empty()) {
        // decompose 4x4 transform matrix into TRS
        aiVector3D t, r, s;
        node->mTransformation.Decompose(s, r, t);
        if (t != zero) {
            p.AddP70(
                "Lcl Translation", "Lcl Translation", "", "A",
                double(t.x), double(t.y), double(t.z)
            );
        }
        if (r != zero) {
            p.AddP70(
                "Lcl Rotation", "Lcl Rotation", "", "A",
                double(DEG*r.x), double(DEG*r.y), double(DEG*r.z)
            );
        }
        if (s != one) {
            p.AddP70(
                "Lcl Scaling", "Lcl Scaling", "", "A",
                double(s.x), double(s.y), double(s.z)
            );
        }
    } else {
        // apply the transformation chain.
        // these transformation elements are created when importing FBX,
        // which has a complex transformation hierarchy for each node.
        // as such we can bake the hierarchy back into the node on export.
        for (auto &item : transform_chain) {
            auto elem = transform_types.find(item.first);
            if (elem == transform_types.end()) {
                // then this is a bug
                std::stringstream err;
                err << "unrecognized FBX transformation type: ";
                err << item.first;
                throw DeadlyExportError(err.str());
            }
            const std::string &name = elem->second.first;<--- Shadow variable
            const aiVector3D &v = item.second;
            if (name.compare(0, 4, "Lcl ") == 0) {
                // special handling for animatable properties
                p.AddP70(
                    name, name, "", "A",
                    double(v.x), double(v.y), double(v.z)
                );
            } else {
                p.AddP70vector(name, v.x, v.y, v.z);
            }
        }
    }
    m.AddChild(p);

    // not sure what these are for,
    // but they seem to be omnipresent
    m.AddChild("Shading", FBXExportProperty(true));
    m.AddChild("Culling", FBXExportProperty("CullingOff"));

    m.Dump(outstream, binary, 1);
}

// wrapper for WriteModelNodes to create and pass a blank transform chain
void FBXExporter::WriteModelNodes(
    StreamWriterLE& s,
    const aiNode* node,
    int64_t parent_uid,
    const std::unordered_set<const aiNode*>& limbnodes
) {
    std::vector<std::pair<std::string,aiVector3D>> chain;
    WriteModelNodes(s, node, parent_uid, limbnodes, chain);
}

void FBXExporter::WriteModelNodes(
    StreamWriterLE& outstream,
    const aiNode* node,
    int64_t parent_uid,
    const std::unordered_set<const aiNode*>& limbnodes,
    std::vector<std::pair<std::string,aiVector3D>>& transform_chain
) {
    // first collapse any expanded transformation chains created by FBX import.
    std::string node_name(node->mName.C_Str());
    if (node_name.find(MAGIC_NODE_TAG) != std::string::npos) {
        auto pos = node_name.find(MAGIC_NODE_TAG) + MAGIC_NODE_TAG.size() + 1;
        std::string type_name = node_name.substr(pos);
        auto elem = transform_types.find(type_name);
        if (elem == transform_types.end()) {
            // then this is a bug and should be fixed
            std::stringstream err;
            err << "unrecognized FBX transformation node";
            err << " of type " << type_name << " in node " << node_name;
            throw DeadlyExportError(err.str());
        }
        aiVector3D t, r, s;
        node->mTransformation.Decompose(s, r, t);
        switch (elem->second.second) {
        case 'i': // inverse
            // we don't need to worry about the inverse matrices
            break;
        case 't': // translation
            transform_chain.emplace_back(elem->first, t);
            break;
        case 'r': // rotation
            r *= float(DEG);
            transform_chain.emplace_back(elem->first, r);
            break;
        case 's': // scale
            transform_chain.emplace_back(elem->first, s);
            break;
        default:
            // this should never happen
            std::stringstream err;
            err << "unrecognized FBX transformation type code: ";
            err << elem->second.second;
            throw DeadlyExportError(err.str());
        }
        // now continue on to any child nodes
        for (unsigned i = 0; i < node->mNumChildren; ++i) {
            WriteModelNodes(
                outstream,
                node->mChildren[i],
                parent_uid,
                limbnodes,
                transform_chain
            );
        }
        return;
    }

    int64_t node_uid = 0;
    // generate uid and connect to parent, if not the root node,
    if (node != mScene->mRootNode) {
        auto elem = node_uids.find(node);
        if (elem != node_uids.end()) {
            node_uid = elem->second;
        } else {
            node_uid = generate_uid();
            node_uids[node] = node_uid;
        }
        connections.emplace_back("C", "OO", node_uid, parent_uid);
    }

    // what type of node is this?
    if (node == mScene->mRootNode) {
        // handled later
    } else if (node->mNumMeshes == 1) {
        // connect to child mesh, which should have been written previously
        connections.emplace_back(
            "C", "OO", mesh_uids[node->mMeshes[0]], node_uid
        );
        // also connect to the material for the child mesh
        connections.emplace_back(
            "C", "OO",
            material_uids[mScene->mMeshes[node->mMeshes[0]]->mMaterialIndex],
            node_uid
        );
        // write model node
        WriteModelNode(
            outstream, binary, node, node_uid, "Mesh", transform_chain
        );
    } else if (limbnodes.count(node)) {
        WriteModelNode(
            outstream, binary, node, node_uid, "LimbNode", transform_chain
        );
        // we also need to write a nodeattribute to mark it as a skeleton
        int64_t node_attribute_uid = generate_uid();
        FBX::Node na("NodeAttribute");
        na.AddProperties(
            node_attribute_uid, FBX::SEPARATOR + "NodeAttribute", "LimbNode"
        );
        na.AddChild("TypeFlags", FBXExportProperty("Skeleton"));
        na.Dump(outstream, binary, 1);
        // and connect them
        connections.emplace_back("C", "OO", node_attribute_uid, node_uid);
    } else {
        // generate a null node so we can add children to it
        WriteModelNode(
            outstream, binary, node, node_uid, "Null", transform_chain
        );
    }

    // if more than one child mesh, make nodes for each mesh
    if (node->mNumMeshes > 1 || node == mScene->mRootNode) {
        for (size_t i = 0; i < node->mNumMeshes; ++i) {
            // make a new model node
            int64_t new_node_uid = generate_uid();
            // connect to parent node
            connections.emplace_back("C", "OO", new_node_uid, node_uid);
            // connect to child mesh, which should have been written previously
            connections.emplace_back(
                "C", "OO", mesh_uids[node->mMeshes[i]], new_node_uid
            );
            // also connect to the material for the child mesh
            connections.emplace_back(
                "C", "OO",
                material_uids[
                    mScene->mMeshes[node->mMeshes[i]]->mMaterialIndex
                ],
                new_node_uid
            );
            // write model node
            FBX::Node m("Model");
            // take name from mesh name, if it exists
            std::string name = mScene->mMeshes[node->mMeshes[i]]->mName.C_Str();
            name += FBX::SEPARATOR + "Model";
            m.AddProperties(new_node_uid, name, "Mesh");
            m.AddChild("Version", int32_t(232));
            FBX::Node p("Properties70");
            p.AddP70enum("InheritType", 1);
            m.AddChild(p);
            m.Dump(outstream, binary, 1);
        }
    }

    // now recurse into children
    for (size_t i = 0; i < node->mNumChildren; ++i) {
        WriteModelNodes(
            outstream, node->mChildren[i], node_uid, limbnodes
        );
    }
}


void FBXExporter::WriteAnimationCurveNode(
    StreamWriterLE& outstream,
    int64_t uid,
    const std::string& name, // "T", "R", or "S"
    aiVector3D default_value,
    std::string property_name, // "Lcl Translation" etc
    int64_t layer_uid,
    int64_t node_uid
) {
    FBX::Node n("AnimationCurveNode");
    n.AddProperties(uid, name + FBX::SEPARATOR + "AnimCurveNode", "");
    FBX::Node p("Properties70");
    p.AddP70numberA("d|X", default_value.x);
    p.AddP70numberA("d|Y", default_value.y);
    p.AddP70numberA("d|Z", default_value.z);
    n.AddChild(p);
    n.Dump(outstream, binary, 1);
    // connect to layer
    this->connections.emplace_back("C", "OO", uid, layer_uid);
    // connect to bone
    this->connections.emplace_back("C", "OP", uid, node_uid, property_name);
}


void FBXExporter::WriteAnimationCurve(
    StreamWriterLE& outstream,
    double default_value,
    const std::vector<int64_t>& times,
    const std::vector<float>& values,
    int64_t curvenode_uid,
    const std::string& property_link // "d|X", "d|Y", etc
) {
    FBX::Node n("AnimationCurve");
    int64_t curve_uid = generate_uid();
    n.AddProperties(curve_uid, FBX::SEPARATOR + "AnimCurve", "");
    n.AddChild("Default", default_value);
    n.AddChild("KeyVer", int32_t(4009));
    n.AddChild("KeyTime", times);
    n.AddChild("KeyValueFloat", values);
    // TODO: keyattr flags and data (STUB for now)
    n.AddChild("KeyAttrFlags", std::vector<int32_t>{0});
    n.AddChild("KeyAttrDataFloat", std::vector<float>{0,0,0,0});
    n.AddChild(
        "KeyAttrRefCount",
        std::vector<int32_t>{static_cast<int32_t>(times.size())}
    );
    n.Dump(outstream, binary, 1);
    this->connections.emplace_back(
        "C", "OP", curve_uid, curvenode_uid, property_link
    );
}


void FBXExporter::WriteConnections ()
{
    // we should have completed the connection graph already,
    // so basically just dump it here
    if (!binary) {
        WriteAsciiSectionHeader("Object connections");
    }
    // TODO: comments with names in the ascii version
    FBX::Node conn("Connections");
    StreamWriterLE outstream(outfile);
    conn.Begin(outstream, binary, 0);
    conn.BeginChildren(outstream, binary, 0);
    for (auto &n : connections) {
        n.Dump(outstream, binary, 1);
    }
    conn.End(outstream, binary, 0, !connections.empty());
    connections.clear();
}

#endif // ASSIMP_BUILD_NO_FBX_EXPORTER
#endif // ASSIMP_BUILD_NO_EXPORT