Implement internal ktxdiff tool for comparing test output files

CMakeLists.txt

@@ -71,6 +71,16 @@ CMAKE_DEPENDENT_OPTION( BASISU_SUPPORT_OPENCL
     OFF
 )
 
+# To improve deterministic outputs enable precise floating point operations
+if(MSVC)
+    add_compile_options(/fp:precise)
+else()
+    add_compile_options(-ffp-contract=off)
+    if(${CMAKE_CXX_COMPILER_ID} MATCHES "Clang")
+        add_compile_options(-ffp-model=precise)
+    endif()
+endif()
+
 if(BASISU_SUPPORT_OPENCL)
     find_package(OpenCL)
 endif()
@@ -356,10 +366,11 @@ 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()
 
@@ -955,6 +966,7 @@ else()
 endif()
 
 # Other external projects
+set(FMT_SYSTEM_HEADERS ON)
 add_subdirectory(other_projects/fmt)
 add_subdirectory(other_projects/cxxopts)
 

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>
+)

tools/ktx/encode_utils.h

@@ -107,7 +107,7 @@ enum class EncodeCodec {
             <tr><td>4   </td><td> Very slow </td><td> 48.24dB</td></tr>
             </table>
 
-            You are strongly encouraged to also specify @b --zcmp to
+            You are strongly encouraged to also specify @b --zstd to
             losslessly compress the UASTC data. This and any LZ-style
             compression can be made more effective by conditioning the
             UASTC texture data using the Rate Distortion Optimization (RDO)

tools/ktx/image.hpp

@@ -1248,7 +1248,9 @@ class ImageT : public Image {
             // Encode destination transfer function
             for (uint32_t comp = 0; comp < components; comp++) {
                 brightness[comp] = encode.encode(intensity[comp]);
-                c.set(comp, roundf(brightness[comp] * static_cast<float>(Color::one())));
+                // max(0, value) is required as static_cast from negative float to integrals has platform-specific behaviors
+                // and on certian platforms it can incorrectly wrap around
+                c.set(comp, std::max(0.f, roundf(brightness[comp] * static_cast<float>(Color::one()))));
             }
         }
         return *this;