Decode BasisU textures to BCn format instead of RGBA8

CHANGES.md

@@ -1,5 +1,9 @@
 # Change Log
 
+### v0.12.0 - 2023-11-01
+
+* Basis Universal textures are now decoded to the native BCn texture format instead of RGBA8 in Kit 105.1 and above.
+
 ### v0.11.0 - 2023-10-02
 
 * **Breaking change:** Cesium for Omniverse now requires Kit 105.1 or above (USD Composer 2023.2.0 or above).

src/core/src/FabricTexture.cpp

@@ -1,5 +1,6 @@
 #include "cesium/omniverse/FabricTexture.h"
 
+#include "cesium/omniverse/LoggerSink.h"
 #include "cesium/omniverse/UsdUtil.h"
 
 #include <CesiumGltf/ImageCesium.h>
@@ -10,6 +11,27 @@
 
 namespace cesium::omniverse {
 
+namespace {
+carb::Format getCompressedImageFormat(CesiumGltf::GpuCompressedPixelFormat pixelFormat) {
+    switch (pixelFormat) {
+        case CesiumGltf::GpuCompressedPixelFormat::BC1_RGB:
+            return carb::Format::eBC1_RGBA_SRGB;
+        case CesiumGltf::GpuCompressedPixelFormat::BC3_RGBA:
+            return carb::Format::eBC3_RGBA_SRGB;
+        case CesiumGltf::GpuCompressedPixelFormat::BC4_R:
+            return carb::Format::eBC4_R_UNORM;
+        case CesiumGltf::GpuCompressedPixelFormat::BC5_RG:
+            return carb::Format::eBC5_RG_UNORM;
+        case CesiumGltf::GpuCompressedPixelFormat::BC7_RGBA:
+            return carb::Format::eBC7_RGBA_SRGB;
+        default:
+            // Unsupported compressed texture format.
+            return carb::Format::eUnknown;
+    };
+}
+
+} // namespace
+
 FabricTexture::FabricTexture(const std::string& name)
     : _texture(std::make_unique<omni::ui::DynamicTextureProvider>(name))
     , _assetPathToken(UsdUtil::getDynamicTextureProviderAssetPathToken(name)) {
@@ -35,11 +57,22 @@ void FabricTexture::reset() {
 }
 
 void FabricTexture::setImage(const CesiumGltf::ImageCesium& image) {
-    _texture->setBytesData(
-        reinterpret_cast<const uint8_t*>(image.pixelData.data()),
-        carb::Uint2{static_cast<uint32_t>(image.width), static_cast<uint32_t>(image.height)},
-        omni::ui::kAutoCalculateStride,
-        carb::Format::eRGBA8_SRGB);
+    auto imageFormat = carb::Format::eRGBA8_SRGB;
+
+    if (image.compressedPixelFormat != CesiumGltf::GpuCompressedPixelFormat::NONE) {
+        imageFormat = getCompressedImageFormat(image.compressedPixelFormat);
+    }
+
+    if (imageFormat == carb::Format::eUnknown) {
+        CESIUM_LOG_WARN("Invalid image format");
+    } else {
+        // As of Kit 105.1, omni::ui::kAutoCalculateStride doesn't work for compressed textures. This value somehow works.
+        const auto stride = 4ULL * static_cast<uint64_t>(image.width);
+        const auto data = reinterpret_cast<const uint8_t*>(image.pixelData.data());
+        const auto dimensions = carb::Uint2{static_cast<uint32_t>(image.width), static_cast<uint32_t>(image.height)};
+
+        _texture->setBytesData(data, dimensions, stride, imageFormat);
+    }
 }
 
 } // namespace cesium::omniverse

src/core/src/OmniTileset.cpp

@@ -329,6 +329,26 @@ void OmniTileset::reload() {
             CESIUM_LOG_ERROR(error.message);
         };
 
+    CesiumGltf::SupportedGpuCompressedPixelFormats supportedFormats;
+
+    // Only BCN compressed texture formats are supported in Omniverse
+    supportedFormats.ETC1_RGB = false;
+    supportedFormats.ETC2_RGBA = false;
+    supportedFormats.BC1_RGB = true;
+    supportedFormats.BC3_RGBA = true;
+    supportedFormats.BC4_R = true;
+    supportedFormats.BC5_RG = true;
+    supportedFormats.BC7_RGBA = true;
+    supportedFormats.PVRTC1_4_RGB = false;
+    supportedFormats.PVRTC1_4_RGBA = false;
+    supportedFormats.ASTC_4x4_RGBA = false;
+    supportedFormats.PVRTC2_4_RGB = false;
+    supportedFormats.PVRTC2_4_RGBA = false;
+    supportedFormats.ETC2_EAC_R11 = false;
+    supportedFormats.ETC2_EAC_RG11 = false;
+
+    options.contentOptions.ktx2TranscodeTargets = CesiumGltf::Ktx2TranscodeTargets(supportedFormats, false);
+
     _pViewUpdateResult = nullptr;
     _extentSet = false;
     _activeLoading = false;