Improve output determinism and add internal ktxdiff tool for comparin…

…g test outputs (#745)

* Implement internal ktxdiff tool for comparing test output files.
* Fix color conversion overflow.

CMakeLists.txt

@@ -254,6 +254,55 @@ else()
     message(FATAL_ERROR "${CMAKE_CXX_COMPILER_ID} not yet supported.")
 endif()
 
+# To improve output determinism enable precise floating point operations globally
+# This code was based on lib/astc-encoder/Source/cmake_core.cmake
+
+# For Visual Studio prior to 2022 (compiler < 19.30) /fp:strict
+# For Visual Studio 2022 (compiler >= 19.30) /fp:precise
+# For Visual Studio 2022 ClangCL seems to have accidentally enabled contraction by default,
+# so behaves differently to CL.exe. Use the -Xclang argument to workaround and allow access
+# GNU-style switch to control contraction and force disable.
+
+# On CMake 3.25 or older CXX_COMPILER_FRONTEND_VARIANT is not always set
+if(CMAKE_CXX_COMPILER_FRONTEND_VARIANT STREQUAL "")
+    set(CMAKE_CXX_COMPILER_FRONTEND_VARIANT "${CMAKE_CXX_COMPILER_ID}")
+endif()
+
+# Compiler accepts MSVC-style command line options
+set(is_msvc_fe "$<STREQUAL:${CMAKE_CXX_COMPILER_FRONTEND_VARIANT},MSVC>")
+# Compiler accepts GNU-style command line options
+set(is_gnu_fe1 "$<STREQUAL:${CMAKE_CXX_COMPILER_FRONTEND_VARIANT},GNU>")
+# Compiler accepts AppleClang-style command line options, which is also GNU-style
+set(is_gnu_fe2 "$<STREQUAL:${CMAKE_CXX_COMPILER_FRONTEND_VARIANT},AppleClang>")
+# Compiler accepts GNU-style command line options
+set(is_gnu_fe "$<OR:${is_gnu_fe1},${is_gnu_fe2}>")
+
+# Compiler is Visual Studio cl.exe
+set(is_msvccl "$<AND:${is_msvc_fe},$<CXX_COMPILER_ID:MSVC>>")
+# Compiler is Visual Studio clangcl.exe
+set(is_clangcl "$<AND:${is_msvc_fe},$<CXX_COMPILER_ID:Clang>>")
+# Compiler is upstream clang with the standard frontend
+set(is_clang "$<AND:${is_gnu_fe},$<CXX_COMPILER_ID:Clang,AppleClang>>")
+
+if(${is_msvccl} AND $<VERSION_LESS:$<CXX_COMPILER_VERSION>,19.30>)
+    add_compile_options(/fp:strict)
+endif()
+if(${is_msvccl} AND $<VERSION_GREATER_EQUAL:$<CXX_COMPILER_VERSION>,19.30>)
+    add_compile_options(/fp:precise)
+endif()
+if(${is_clangcl})
+    add_compile_options(/fp:precise)
+endif()
+if(${is_clangcl} AND $<VERSION_GREATER_EQUAL:$<CXX_COMPILER_VERSION>,14.0.0>)
+    add_compile_options(-Xclang -ffp-contract=off)
+endif()
+if(${is_clang} AND $<VERSION_GREATER_EQUAL:$<CXX_COMPILER_VERSION>,10.0.0>)
+    add_compile_options(-ffp-model=precise)
+endif()
+if(${is_gnu_fe})
+    add_compile_options(-ffp-contract=off)
+endif()
+
 set(KTX_BUILD_DIR "${CMAKE_BINARY_DIR}")
 
 set(KTX_MAIN_SRC
@@ -361,10 +410,11 @@ if(WIN32)
     set(CMAKE_RUNTIME_OUTPUT_DIRECTORY $<1:${KTX_BUILD_DIR}/$<CONFIG>>)
 elseif(APPLE)
     if(NOT IOS)
-        # Set a common RUNTIME_OUTPUT_DIR for all targets, so that
-        # INSTALL RPATH is functional in build directory as well.
+        # Set a common RUNTIME_OUTPUT_DIR and LIBRARY_OUTPUT_DIR for all targets,
+        # so that INSTALL RPATH is functional in build directory as well.
         # BUILD_WITH_INSTALL_RPATH is necessary for working code signing.
         set(CMAKE_RUNTIME_OUTPUT_DIRECTORY $<1:${KTX_BUILD_DIR}/$<CONFIG>>)
+        set(CMAKE_LIBRARY_OUTPUT_DIRECTORY $<1:${KTX_BUILD_DIR}/$<CONFIG>>)
     endif()
 endif()
 

tests/CMakeLists.txt

@@ -28,7 +28,9 @@ if(KTX_FEATURE_TOOLS)
 
     # ktx cli tool tests
     if(KTX_FEATURE_TOOLS_CTS)
+        add_subdirectory(ktxdiff)
         set(KTX_TOOLS_PATH $<TARGET_FILE:ktxtools>)
+        set(KTX_DIFF_PATH $<TARGET_FILE:ktxdiff>)
         add_subdirectory(cts/clitests)
     endif()
 endif()

tests/ktxdiff/CMakeLists.txt

@@ -0,0 +1,44 @@
+# Copyright 2022-2023 The Khronos Group Inc.
+# Copyright 2022-2023 RasterGrid Kft.
+# SPDX-License-Identifier: Apache-2.0
+
+
+add_executable(ktxdiff
+        ktxdiff_main.cpp
+)
+
+set_target_properties(
+    ktxdiff
+    PROPERTIES
+        CXX_STANDARD 17
+        CXX_STANDARD_REQUIRED YES
+)
+
+target_include_directories(
+    ktxdiff
+PRIVATE
+    .
+    $<TARGET_PROPERTY:ktx,INCLUDE_DIRECTORIES>
+)
+
+target_include_directories(
+    ktxdiff
+    SYSTEM
+PRIVATE
+    ${PROJECT_SOURCE_DIR}/lib
+    ${PROJECT_SOURCE_DIR}/other_include
+)
+
+target_link_libraries(
+    ktxdiff
+PRIVATE
+    ktx
+    ${ASTCENC_LIB_TARGET}
+    fmt::fmt
+)
+
+target_compile_definitions(
+    ktxdiff
+PRIVATE
+    $<TARGET_PROPERTY:ktx,INTERFACE_COMPILE_DEFINITIONS>
+)