This renderer has passed every test this model has to offer.
This model tests if KHR_texture_transform is supported across a variety of different texture inputs, and whether TEXCOORD_1 works and is also transformed.
NOTE: When implementing KHR_texture_transform, it is recommended to test TextureTransformTest prior to testing this model.
To pass every test this model offers, an implementation should render rows of checkmarks, where each of the three tiles in a row look virtually identical. Note that some of the rows may be very low-contrast, depending on the camera angle and lighting conditions. A very bright, detailed reflection environment is recommended for optimal testing conditions.
This column renders a checkmark using TEXCOORD_0 coordinates, transformed by KHR_texture_transform. If the texture transform is not applied, a crossed-out circle will be visible. If the TEXCOORD_0 coordinates have not been used, the box may be blank.
This column works the same as the previous column, except it uses TEXCOORD_1 coordinates, transformed by KHR_texture_transform.
This column offers only a single set of texture coordinates, and does not require any transformation. It is intended to be a control column, showing what the checkmark looks like rendered in the row's input channel under test. Some inputs such as Clearcoat may be un-supported, in which case all 3 boxes will be completely dark. That can still be considered a "pass" for this model, as the goal is to test texture coordinates and transforms here, not Clearcoat support.
The "Occlusion" row may appear blank when rendered in path tracers or ray tracers that calculate their own ambient occlusion. That can also be considered a "pass."
In the above test, the renderer has produced a "UV 1" column that is identical to "UV 0", indicating it has done a good job processing TEXCOORD_0 and TEXCOORD_1 the same way. However, it displays crossed-out circles for the "Normal" and "Occlusion" inputs, indicating that KHR_texture_transform has not been applied to those two inputs.
If an "X" or other improper shape appears, it likely indicates that the KHR_texture_transform math has not been correctly applied. Try the TextureTransformTest model, to test each piece of the transformation individually.
If the crossed-out circle appears, it means that no transformation has been applied at all.
The renderer that produced this image has a known limitation, where TEXCOORD_1 is only supported for the Occlusion input. This manifests itself as blank boxes down most of the "UV 1" column, except for Occlusion.
But an additional limitation is revealed here: In the "Occlusion" "UV 0" test is also showing a blank box. The mere presence of multiple UV sets in that box has caused this renderer to improperly use TEXCOORD_1, disregarding the model's UV index 0 selection. But in the "Sample" column, only one set of UVs are available, so the checkmark is correctly rendered there.
The Clearcoat tests can be dark and low-contrast, an unfortunate consequence of the subtle nature of the clear coating. Use a bright reflection environment, or possibly post-process the resulting image in a paint program to bring out more contrast, as shown here. Two of the rows have curved test boxes, to help reflect more of the surrounding environment.
The "UV 1" boxes shown here are blank due to a known limitation in this rendering engine, described above. But the "UV 0" boxes are showing the crossed-out circle. This indicates that KHR_texture_transform has not been applied to any of the Clearcoat inputs.
Copyright 2020 Analytical Graphics, Inc. CC-BY 4.0 https://creativecommons.org/licenses/by/4.0/ Model and textures by Ed Mackey.