This README visualizes a subset of the graphical tests and serves as an artifact for discussion around
- the conformance of guc and the MaterialX glTF PBR implementation
- UsdPreviewSurface limitations and shading differences
- existing problems in guc and involved technologies.
Note: please see run_tests.sh for additional notes and deactivated tests.
glTF-Asset-Generator (source)
| Index | USD+UsdPreviewSurface | USD+MaterialX | glTF Ref. |
|---|---|---|---|
| Accessor_Sparse | |||
| 02 |  |
 |
 |
| 03 |  |
 |
 |
| Accessor_SparseType | |||
| 05 |  |
 |
 |
| Buffer_Interleaved | |||
| 00 |  |
 |
|
| 01 |  |
 |
|
| 02 |  |
 |
|
| 03 |  |
 |
|
| 04 |  |
 |
|
| Instancing | |||
| 00 |  |
 |
 |
| 01 |  |
 |
 |
| 02 |  |
 |
 |
| 03 |  |
 |
 |
| 04 |  |
 |
 |
| 05 |  |
 |
 |
| 06 |  |
 |
 |
| 07 |  |
 |
 |
| Material | |||
| 00 |  |
 |
 |
| 01 |  |
 |
 |
| 02 |  |
 |
 |
| 03 |  |
 |
 |
| 04 |  |
 |
 |
| 05 |  |
 |
 |
| 06 |  |
 |
 |
| 07 |  |
 |
 |
| Material_AlphaBlend | |||
| 00 |  |
 |
|
| 01 |  |
 |
 |
| 02 |  |
 |
 |
| 03 |  |
 |
|
| 04 |  |
 |
|
| 05 |  |
 |
 |
| 06 |  |
 |
|
| Material_AlphaMask | |||
| 00 |  |
 |
 |
| 01 |  |
 |
 |
| 02 |  |
 |
 |
| 03 |  |
 |
 |
| 04 |  |
 |
 |
| 05 |  |
 |
 |
| 06 |  |
 |
 |
| Material_DoubleSided | |||
| 00 |  |
 |
 |
| 01 |  |
 |
 |
| 02 |  |
 |
 |
| 03 |  |
 |
|
| 04 |  |
 |
 |
| Material_MetallicRoughness | |||
| 00 |  |
 |
 |
| 01 |  |
 |
|
| 02 |  |
 |
 |
| 03 |  |
 |
 |
| 04 |  |
 |
 |
| 05 |  |
 |
 |
| 06 |  |
 |
 |
| 07 |  |
 |
|
| 08 |  |
 |
 |
| 09 |  |
 |
 |
| 10 |  |
 |
 |
| 11 |  |
 |
|
| Mesh_PrimitiveAttribute | |||
| 00 |  |
 |
 |
| 01 |  |
 |
 |
| 02 |  |
 |
 |
| 03 |  |
 |
 |
| 04 |  |
 |
 |
| 05 |  |
 |
 |
| 06 |  |
 |
|
| Mesh_PrimitiveMode | |||
| 04 |  |
 |
 |
| 05 |  |
 |
 |
| 06 |  |
 |
 |
| 11 |  |
 |
 |
| 12 |  |
 |
 |
| 13 |  |
 |
 |
| 14 |  |
 |
 |
| 15 |  |
 |
 |
| Mesh_PrimitiveVertexColor | |||
| 00 |  |
 |
|
| 01 |  |
 |
|
| 02 |  |
 |
|
| 03 |  |
 |
|
| 04 |  |
 |
|
| 05 |  |
 |
|
| Mesh_Primitives | |||
| 00 |  |
 |
 |
| Mesh_PrimitivesUV | |||
| 00 |  |
 |
 |
| 01 |  |
 |
|
| 02 |  |
 |
|
| 03 |  |
 |
|
| 04 |  |
 |
|
| 05 |  |
 |
|
| 06 |  |
 |
|
| 07 |  |
 |
|
| 08 |  |
 |
|
| Node_Attribute | |||
| 00 |  |
 |
 |
| 01 |  |
 |
 |
| 02 |  |
 |
 |
| 03 |  |
 |
 |
| 04 |  |
 |
 |
| 05 |  |
 |
 |
| 06 |  |
 |
 |
| 07 |  |
 |
 |
| 08 |  |
 |
 |
| Node_NegativeScale | |||
| 00 |  |
 |
 |
| 01 |  |
 |
 |
| 02 |  |
 |
 |
| 03 |  |
 |
 |
| 04 |  |
 |
 |
| 05 |  |
 |
 |
| 06 |  |
 |
 |
| 07 |  |
 |
 |
| 08 |  |
 |
 |
| 09 |  |
 |
 |
| 10 |  |
 |
|
| 11 |  |
 |
|
| 12 |  |
 |
|
| Texture_Sampler | |||
| 00 |  |
 |
|
| 01 |  |
 |
|
| 02 |  |
 |
|
| 03 |  |
 |
|
| 04 |  |
 |
|
| 05 |  |
 |
|
| 06 |  |
 |
|
| 07 |  |
 |
|
| 08 |  |
 |
|
| 09 |  |
 |
|
| 10 |  |
 |
|
| 11 |  |
 |
|
| 12 |  |
 |
|
| 13 |  |
 |
|
glTF-Sample-Models (source)
Complex Models
| Name | USD+UsdPreviewSurface | USD+MaterialX |
|---|---|---|
| 2CylinderEngine |  |
 |
| ABeautifulGame |  |
 |
| DamagedHelmet |  |
 |
| IridescenceLamp |  |
 |
| IridescentDishWithOlives |  |
 |
| MosquitoInAmber |  |
 |
| SheenCloth |  |
 |
| StainedGlassLamp |  |
 |
| ToyCar |  |
 |
Feature Tests
| Name | USD+UsdPreviewSurface | USD+MaterialX |
|---|---|---|
| AlphaBlendModeTest |  |
 |
| AttenuationTest |  |
 |
| ClearCoatTest |  |
 |
| EmissiveStrengthTest |  |
 |
| EnvironmentTest |  |
 |
| IridescenceDielectricSpheres |  |
 |
| IridescenceMetallicSpheres |  |
 |
| LightsPunctualLamp |  |
 |
| MetalRoughSpheres |  |
 |
| MetalRoughSpheresNoTextures |  |
 |
| MultiUVTest |  |
 |
| NormalTangentMirrorTest |  |
 |
| NormalTangentTest |  |
 |
| OrientationTest |  |
 |
| SpecularTest |  |
 |
| TextureCoordinateTest |  |
 |
| TextureEncodingTest |  |
 |
| TextureSettingsTest |  |
 |
| TextureTransformTest |  |
 |
| TextureTransformMultiTest |  |
 |
| TransmissionRoughnessTest |  |
 |
| TransmissionTest |  |
 |
| UnlitTest |  |
 |
| VertexColorTest |  |
 |
| Name | USD+UsdPreviewSurface | USD+MaterialX |
|---|---|---|
| Camera_01 |  |
 |
| CoffeeCart_01 |  |
 |
| Fangyi |  |
 |
| Loewe_von_Asparn |  |
 |
| Perseverance |  |
 |
| Space_Shuttle |  |
 |
| MaterialVariants | ||
|---|---|---|
| Variant | UsdPreviewSurface | MaterialX |
| Midnight (0, default) |  |
 |
| Beach (1) |  |
 |
Minor observations:
- Brightness differences
Most notably in the glTF-Asset-Generator tests. Between UsdPreviewSurface and the glTF PBR, the specular response may be the cause (see MetalRoughSpheresNoTextures). Differences between MaterialX and the glTF reference renders may be caused by their lighting setups. - Shadowing differences
For instance, in the AlphaBlendModeTest. These can be attributed to the different handling of shadows in HdStorm's MaterialX integration. - Missing transmission color attenuation
For instance, in the TransmissionTest sample model. This seems to be a current limitation of HdStorm's MaterialX integration. - TextureSettingsTest seems to fail
It's actually working, but backface culling is disabled by default.
Failures:
- Material_04 looks more specular than it should
This hints at an actual issue in either 1) guc's handling of normal maps, 2) the MaterialX glTF PBR implementation, 3) MaterialXGenGlsl or 4) HdStorm. - ToyCar model cloth is too bright and has shading artifacts
The artifacts exist in MaterialXView too, suggesting an issue with the GLSL sheen implementation, or the MaterialX glTF PBR.