Fix invalid ktx2 files/update them for KTX v4.3.2

[JMLX42]

Hello,

I have re-generated all the .ktx2 files because they would not pass ktx2check. All files should not be valid according to KTX Tools v4.3.2.

I also added prefilter.sh, which is the Bash equivalent of prefilter.bat.

Let me know if something else needs to be done for this to be merged!

[javagl]

*looks left* *looks right* *looks confused* 🙂 Does anybody feel responsible for reviewing and merging this?

I'm not sure what the source of truth is here. There is ktx2check and ktx validate. I assume that they should be ... somehow equivalent...? But ktx validate seems to print more information. I think it's the more recent way of validating stuff.

So... I created some BAT file

echo off
for /R %%f in (*.ktx2) do (
  echo Validating %%f...
  ktx validate %%f
  echo Validating %%f DONE
)

and ran it on main. There, basically every file contains errors.

On this branch, there are still some errors:

C:\glTF-Sample-Environments>echo off 
Validating C:\glTF-Sample-Environments\chromatic\charlie\sheen.ktx2...
Validating C:\glTF-Sample-Environments\chromatic\charlie\sheen.ktx2 DONE
Validating C:\glTF-Sample-Environments\chromatic\ggx\specular.ktx2...
Validating C:\glTF-Sample-Environments\chromatic\ggx\specular.ktx2 DONE
Validating C:\glTF-Sample-Environments\chromatic\lambertian\diffuse.ktx2...
Validating C:\glTF-Sample-Environments\chromatic\lambertian\diffuse.ktx2 DONE
Validating C:\glTF-Sample-Environments\directional\charlie\sheen.ktx2...
Validating C:\glTF-Sample-Environments\directional\charlie\sheen.ktx2 DONE
Validating C:\glTF-Sample-Environments\directional\ggx\specular.ktx2...
Validating C:\glTF-Sample-Environments\directional\ggx\specular.ktx2 DONE
Validating C:\glTF-Sample-Environments\directional\lambertian\diffuse.ktx2...
Validating C:\glTF-Sample-Environments\directional\lambertian\diffuse.ktx2 DONE
Validating C:\glTF-Sample-Environments\doge2\charlie\sheen.ktx2...
Validating C:\glTF-Sample-Environments\doge2\charlie\sheen.ktx2 DONE
Validating C:\glTF-Sample-Environments\doge2\ggx\specular.ktx2...
Validating C:\glTF-Sample-Environments\doge2\ggx\specular.ktx2 DONE
Validating C:\glTF-Sample-Environments\doge2\lambertian\diffuse.ktx2...
Validating C:\glTF-Sample-Environments\doge2\lambertian\diffuse.ktx2 DONE
Validating C:\glTF-Sample-Environments\ennis\charlie\charlie.ktx2...
Validation failed

error-3020: Missing Data Format Descriptor.
    Data Format Descriptor is mandatory but dfdByteOffset is 0 and dfdByteLength is 0.
error-3021: Invalid dfdByteOffset.
    dfdByteOffset is 0 but the Data Format Descriptor must immediately follow (with 4 byte alignment) the Level Index so it must be 344.
Validating C:\glTF-Sample-Environments\ennis\charlie\charlie.ktx2 DONE
Validating C:\glTF-Sample-Environments\ennis\charlie\sheen.ktx2...
Validating C:\glTF-Sample-Environments\ennis\charlie\sheen.ktx2 DONE
Validating C:\glTF-Sample-Environments\ennis\ggx\specular.ktx2...
Validating C:\glTF-Sample-Environments\ennis\ggx\specular.ktx2 DONE
Validating C:\glTF-Sample-Environments\ennis\lambertian\diffuse.ktx2...
Validating C:\glTF-Sample-Environments\ennis\lambertian\diffuse.ktx2 DONE
Validating C:\glTF-Sample-Environments\ennis\lambertian\outputCubeMap.ktx2...
Validation failed

error-3020: Missing Data Format Descriptor.
    Data Format Descriptor is mandatory but dfdByteOffset is 0 and dfdByteLength is 0.
error-3021: Invalid dfdByteOffset.
    dfdByteOffset is 0 but the Data Format Descriptor must immediately follow (with 4 byte alignment) the Level Index so it must be 344.
Validating C:\glTF-Sample-Environments\ennis\lambertian\outputCubeMap.ktx2 DONE
Validating C:\glTF-Sample-Environments\field\charlie\sheen.ktx2...
Validating C:\glTF-Sample-Environments\field\charlie\sheen.ktx2 DONE
Validating C:\glTF-Sample-Environments\field\ggx\specular.ktx2...
Validating C:\glTF-Sample-Environments\field\ggx\specular.ktx2 DONE
Validating C:\glTF-Sample-Environments\field\lambertian\diffuse.ktx2...
Validating C:\glTF-Sample-Environments\field\lambertian\diffuse.ktx2 DONE
Validating C:\glTF-Sample-Environments\footprint_court\charlie\sheen.ktx2...
Validation failed

error-6001: Mismatching dfdTotalSize and dfdByteLength. dfdTotalSize must match dfdByteLength.
    dfdTotalSize is 28 but dfdByteLength is 0 and they must match.
error-6015: Invalid colorModel in basic DFD block for RGB VkFormat.
    DFD block #1 colorModel in basic DFD block is KHR_DF_MODEL_UNSPECIFIED but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be KHR_DF_MODEL_RGBSDA.
error-6025: Invalid sample count in basic DFD block. The sample count must match the expected sample count of the VkFormat.
    DFD block #1 sample count in basic DFD block is 0 but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be 4.
error-6021: Invalid bytesPlanes in basic DFD block. The values do not match the expected values.
    DFD block #1 bytesPlanes in basic DFD block are 0 0 0 0 0 0 0 0 but for VK_FORMAT_R16G16B16A16_SFLOAT textures these must be 8 0 0 0 0 0 0 0.
Validating C:\glTF-Sample-Environments\footprint_court\charlie\sheen.ktx2 DONE
Validating C:\glTF-Sample-Environments\footprint_court\ggx\specular.ktx2...
Validation failed

error-6001: Mismatching dfdTotalSize and dfdByteLength. dfdTotalSize must match dfdByteLength.
    dfdTotalSize is 28 but dfdByteLength is 0 and they must match.
error-6015: Invalid colorModel in basic DFD block for RGB VkFormat.
    DFD block #1 colorModel in basic DFD block is KHR_DF_MODEL_UNSPECIFIED but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be KHR_DF_MODEL_RGBSDA.
error-6025: Invalid sample count in basic DFD block. The sample count must match the expected sample count of the VkFormat.
    DFD block #1 sample count in basic DFD block is 0 but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be 4.
error-6021: Invalid bytesPlanes in basic DFD block. The values do not match the expected values.
    DFD block #1 bytesPlanes in basic DFD block are 0 0 0 0 0 0 0 0 but for VK_FORMAT_R16G16B16A16_SFLOAT textures these must be 8 0 0 0 0 0 0 0.
Validating C:\glTF-Sample-Environments\footprint_court\ggx\specular.ktx2 DONE
Validating C:\glTF-Sample-Environments\footprint_court\lambertian\diffuse.ktx2...
Validating C:\glTF-Sample-Environments\footprint_court\lambertian\diffuse.ktx2 DONE
Validating C:\glTF-Sample-Environments\helipad\charlie\sheen.ktx2...
Validation failed

error-6001: Mismatching dfdTotalSize and dfdByteLength. dfdTotalSize must match dfdByteLength.
    dfdTotalSize is 28 but dfdByteLength is 0 and they must match.
error-6015: Invalid colorModel in basic DFD block for RGB VkFormat.
    DFD block #1 colorModel in basic DFD block is KHR_DF_MODEL_UNSPECIFIED but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be KHR_DF_MODEL_RGBSDA.
error-6025: Invalid sample count in basic DFD block. The sample count must match the expected sample count of the VkFormat.
    DFD block #1 sample count in basic DFD block is 0 but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be 4.
error-6021: Invalid bytesPlanes in basic DFD block. The values do not match the expected values.
    DFD block #1 bytesPlanes in basic DFD block are 0 0 0 0 0 0 0 0 but for VK_FORMAT_R16G16B16A16_SFLOAT textures these must be 8 0 0 0 0 0 0 0.
Validating C:\glTF-Sample-Environments\helipad\charlie\sheen.ktx2 DONE
Validating C:\glTF-Sample-Environments\helipad\ggx\specular.ktx2...
Validation failed

error-6001: Mismatching dfdTotalSize and dfdByteLength. dfdTotalSize must match dfdByteLength.
    dfdTotalSize is 28 but dfdByteLength is 0 and they must match.
error-6015: Invalid colorModel in basic DFD block for RGB VkFormat.
    DFD block #1 colorModel in basic DFD block is KHR_DF_MODEL_UNSPECIFIED but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be KHR_DF_MODEL_RGBSDA.
error-6025: Invalid sample count in basic DFD block. The sample count must match the expected sample count of the VkFormat.
    DFD block #1 sample count in basic DFD block is 0 but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be 4.
error-6021: Invalid bytesPlanes in basic DFD block. The values do not match the expected values.
    DFD block #1 bytesPlanes in basic DFD block are 0 0 0 0 0 0 0 0 but for VK_FORMAT_R16G16B16A16_SFLOAT textures these must be 8 0 0 0 0 0 0 0.
Validating C:\glTF-Sample-Environments\helipad\ggx\specular.ktx2 DONE
Validating C:\glTF-Sample-Environments\helipad\lambertian\diffuse.ktx2...
Validating C:\glTF-Sample-Environments\helipad\lambertian\diffuse.ktx2 DONE
Validating C:\glTF-Sample-Environments\neutral\charlie\sheen.ktx2...
Validating C:\glTF-Sample-Environments\neutral\charlie\sheen.ktx2 DONE
Validating C:\glTF-Sample-Environments\neutral\ggx\specular.ktx2...
Validating C:\glTF-Sample-Environments\neutral\ggx\specular.ktx2 DONE
Validating C:\glTF-Sample-Environments\neutral\lambertian\diffuse.ktx2...
Validating C:\glTF-Sample-Environments\neutral\lambertian\diffuse.ktx2 DONE
Validating C:\glTF-Sample-Environments\papermill\charlie\sheen.ktx2...
Validation failed

error-6001: Mismatching dfdTotalSize and dfdByteLength. dfdTotalSize must match dfdByteLength.
    dfdTotalSize is 28 but dfdByteLength is 0 and they must match.
error-6015: Invalid colorModel in basic DFD block for RGB VkFormat.
    DFD block #1 colorModel in basic DFD block is KHR_DF_MODEL_UNSPECIFIED but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be KHR_DF_MODEL_RGBSDA.
error-6025: Invalid sample count in basic DFD block. The sample count must match the expected sample count of the VkFormat.
    DFD block #1 sample count in basic DFD block is 0 but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be 4.
error-6021: Invalid bytesPlanes in basic DFD block. The values do not match the expected values.
    DFD block #1 bytesPlanes in basic DFD block are 0 0 0 0 0 0 0 0 but for VK_FORMAT_R16G16B16A16_SFLOAT textures these must be 8 0 0 0 0 0 0 0.
Validating C:\glTF-Sample-Environments\papermill\charlie\sheen.ktx2 DONE
Validating C:\glTF-Sample-Environments\papermill\ggx\specular.ktx2...
Validation failed

error-6001: Mismatching dfdTotalSize and dfdByteLength. dfdTotalSize must match dfdByteLength.
    dfdTotalSize is 28 but dfdByteLength is 0 and they must match.
error-6015: Invalid colorModel in basic DFD block for RGB VkFormat.
    DFD block #1 colorModel in basic DFD block is KHR_DF_MODEL_UNSPECIFIED but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be KHR_DF_MODEL_RGBSDA.
error-6025: Invalid sample count in basic DFD block. The sample count must match the expected sample count of the VkFormat.
    DFD block #1 sample count in basic DFD block is 0 but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be 4.
error-6021: Invalid bytesPlanes in basic DFD block. The values do not match the expected values.
    DFD block #1 bytesPlanes in basic DFD block are 0 0 0 0 0 0 0 0 but for VK_FORMAT_R16G16B16A16_SFLOAT textures these must be 8 0 0 0 0 0 0 0.
Validating C:\glTF-Sample-Environments\papermill\ggx\specular.ktx2 DONE
Validating C:\glTF-Sample-Environments\papermill\lambertian\diffuse.ktx2...
Validating C:\glTF-Sample-Environments\papermill\lambertian\diffuse.ktx2 DONE
Validating C:\glTF-Sample-Environments\pisa\charlie\sheen.ktx2...
Validating C:\glTF-Sample-Environments\pisa\charlie\sheen.ktx2 DONE
Validating C:\glTF-Sample-Environments\pisa\ggx\specular.ktx2...
Validating C:\glTF-Sample-Environments\pisa\ggx\specular.ktx2 DONE
Validating C:\glTF-Sample-Environments\pisa\lambertian\diffuse.ktx2...
Validating C:\glTF-Sample-Environments\pisa\lambertian\diffuse.ktx2 DONE

Not sure what to do with that, though...

[MarkCallow]

I'm not sure what the source of truth is here. There is ktx2check and ktx validate. I assume that they should be ... somehow equivalent...? But ktx validate seems to print more information. I think it's the more recent way of validating stuff.

You have it right @javagl. ktx validate is more recent, more thorough and replaces ktx2check which will be removed in a future release. All files here must pass ktx validate as these are being presented as official samples to the wide world.

[javagl]

All files here must pass ktx validate

That's what surprised me first: According to the description, the files in this PR have been "freshly" created, and still, many of them fail validation.

But....

(a bit of a rant): This repo is lacking documenation. I read the (comment-free) prefilter.bat, and wondered what cli.exe should be. It took a moment of searching and guessing until I figured out that this happens to be the executable that is created from the glTF-IBL-Sampler (well, call it gltfIblSampler.exe then...).

More importantly: The glTF-IBL-Sampler repo currently uses KTX-Software as a git submodule, with the state https://github.com/KhronosGroup/KTX-Software/tree/d1a25c8a20607a432b2d910a7a761d663c907e8e , which appears to be horribly out-dated.

So (correct me if I'm wrong, but) I think the proper way of updating the sample environments would be:

• Update the git submodule for KTX-Software in glTF-IBL-Sampler to the latest state (preferably a tagged, versioned one)
• Compile the whole thing (and call that executable gltfIblSampler.exe....)
• Run the prefilter.bat (and add comments and a documentation about that in the README.md...)
• Validate the resulting KTX2 files with ktx validate
  • They should pass validation. Otherwise, something somewhere went very wrong...
• Check them in here (i.e. either update this PR acordingly, or (maybe better) create a new PR with the valid files)

[JMLX42]

I have some internal documentation in how to build the CLI, but IMO it does not belong to this repository.

On this branch, there are still some errors:

That is surprising.

IDK if the CLI is using the KTX tools from my system or builds against some vendored lib/source.

I'll have a look and open an issue upstream if relevant.

[JMLX42]

IDK if the CLI is using the KTX tools from my system or builds against some vendored lib/source.

It uses a git-submodules for KTX-Software targeting the 4.0.0 tag. I'll update it to 4.3.2, rebuild, re-process the HDRs and check again.

If everything checks out, I'll open a PR on glTF-IBL-Sampler.

[JMLX42]

Even after updating glTF-IBL-Sampler to KTX-Software 4.3.2, some validation fails:

Validating ./neutral/ggx/specular.ktx2
Validating ./neutral/charlie/sheen.ktx2
Validating ./neutral/lambertian/diffuse.ktx2
Validating ./doge2/ggx/specular.ktx2
Validating ./doge2/charlie/sheen.ktx2
Validating ./doge2/lambertian/diffuse.ktx2
Validating ./helipad/ggx/specular.ktx2
Validation failed

error-6001: Mismatching dfdTotalSize and dfdByteLength. dfdTotalSize must match dfdByteLength.
    dfdTotalSize is 28 but dfdByteLength is 0 and they must match.
error-6015: Invalid colorModel in basic DFD block for RGB VkFormat.
    DFD block #1 colorModel in basic DFD block is KHR_DF_MODEL_UNSPECIFIED but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be KHR_DF_MODEL_RGBSDA.
error-6025: Invalid sample count in basic DFD block. The sample count must match the expected sample count of the VkFormat.
    DFD block #1 sample count in basic DFD block is 0 but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be 4.
error-6021: Invalid bytesPlanes in basic DFD block. The values do not match the expected values.
    DFD block #1 bytesPlanes in basic DFD block are 0 0 0 0 0 0 0 0 but for VK_FORMAT_R16G16B16A16_SFLOAT textures these must be 8 0 0 0 0 0 0 0.
Validating ./helipad/charlie/sheen.ktx2
Validation failed

error-6001: Mismatching dfdTotalSize and dfdByteLength. dfdTotalSize must match dfdByteLength.
    dfdTotalSize is 28 but dfdByteLength is 0 and they must match.
error-6015: Invalid colorModel in basic DFD block for RGB VkFormat.
    DFD block #1 colorModel in basic DFD block is KHR_DF_MODEL_UNSPECIFIED but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be KHR_DF_MODEL_RGBSDA.
error-6025: Invalid sample count in basic DFD block. The sample count must match the expected sample count of the VkFormat.
    DFD block #1 sample count in basic DFD block is 0 but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be 4.
error-6021: Invalid bytesPlanes in basic DFD block. The values do not match the expected values.
    DFD block #1 bytesPlanes in basic DFD block are 0 0 0 0 0 0 0 0 but for VK_FORMAT_R16G16B16A16_SFLOAT textures these must be 8 0 0 0 0 0 0 0.
Validating ./helipad/lambertian/diffuse.ktx2
Validating ./directional/ggx/specular.ktx2
Validating ./directional/charlie/sheen.ktx2
Validating ./directional/lambertian/diffuse.ktx2
Validating ./field/ggx/specular.ktx2
Validating ./field/charlie/sheen.ktx2
Validating ./field/lambertian/diffuse.ktx2
Validating ./pisa/ggx/specular.ktx2
Validating ./pisa/charlie/sheen.ktx2
Validating ./pisa/lambertian/diffuse.ktx2
Validating ./chromatic/ggx/specular.ktx2
Validating ./chromatic/charlie/sheen.ktx2
Validating ./chromatic/lambertian/diffuse.ktx2
Validating ./ennis/ggx/specular.ktx2
Validating ./ennis/charlie/sheen.ktx2
Validating ./ennis/charlie/charlie.ktx2
Validation failed

error-3020: Missing Data Format Descriptor.
    Data Format Descriptor is mandatory but dfdByteOffset is 0 and dfdByteLength is 0.
error-3021: Invalid dfdByteOffset.
    dfdByteOffset is 0 but the Data Format Descriptor must immediately follow (with 4 byte alignment) the Level Index so it must be 344.
Validating ./ennis/lambertian/outputCubeMap.ktx2
Validation failed

error-3020: Missing Data Format Descriptor.
    Data Format Descriptor is mandatory but dfdByteOffset is 0 and dfdByteLength is 0.
error-3021: Invalid dfdByteOffset.
    dfdByteOffset is 0 but the Data Format Descriptor must immediately follow (with 4 byte alignment) the Level Index so it must be 344.
Validating ./ennis/lambertian/diffuse.ktx2
Validating ./footprint_court/ggx/specular.ktx2
Validation failed

error-6001: Mismatching dfdTotalSize and dfdByteLength. dfdTotalSize must match dfdByteLength.
    dfdTotalSize is 28 but dfdByteLength is 0 and they must match.
error-6015: Invalid colorModel in basic DFD block for RGB VkFormat.
    DFD block #1 colorModel in basic DFD block is KHR_DF_MODEL_UNSPECIFIED but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be KHR_DF_MODEL_RGBSDA.
error-6025: Invalid sample count in basic DFD block. The sample count must match the expected sample count of the VkFormat.
    DFD block #1 sample count in basic DFD block is 0 but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be 4.
error-6021: Invalid bytesPlanes in basic DFD block. The values do not match the expected values.
    DFD block #1 bytesPlanes in basic DFD block are 0 0 0 0 0 0 0 0 but for VK_FORMAT_R16G16B16A16_SFLOAT textures these must be 8 0 0 0 0 0 0 0.
Validating ./footprint_court/charlie/sheen.ktx2
Validation failed

error-6001: Mismatching dfdTotalSize and dfdByteLength. dfdTotalSize must match dfdByteLength.
    dfdTotalSize is 28 but dfdByteLength is 0 and they must match.
error-6015: Invalid colorModel in basic DFD block for RGB VkFormat.
    DFD block #1 colorModel in basic DFD block is KHR_DF_MODEL_UNSPECIFIED but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be KHR_DF_MODEL_RGBSDA.
error-6025: Invalid sample count in basic DFD block. The sample count must match the expected sample count of the VkFormat.
    DFD block #1 sample count in basic DFD block is 0 but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be 4.
error-6021: Invalid bytesPlanes in basic DFD block. The values do not match the expected values.
    DFD block #1 bytesPlanes in basic DFD block are 0 0 0 0 0 0 0 0 but for VK_FORMAT_R16G16B16A16_SFLOAT textures these must be 8 0 0 0 0 0 0 0.
Validating ./footprint_court/lambertian/diffuse.ktx2
Validating ./papermill/ggx/specular.ktx2
Validation failed

error-6001: Mismatching dfdTotalSize and dfdByteLength. dfdTotalSize must match dfdByteLength.
    dfdTotalSize is 28 but dfdByteLength is 0 and they must match.
error-6015: Invalid colorModel in basic DFD block for RGB VkFormat.
    DFD block #1 colorModel in basic DFD block is KHR_DF_MODEL_UNSPECIFIED but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be KHR_DF_MODEL_RGBSDA.
error-6025: Invalid sample count in basic DFD block. The sample count must match the expected sample count of the VkFormat.
    DFD block #1 sample count in basic DFD block is 0 but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be 4.
error-6021: Invalid bytesPlanes in basic DFD block. The values do not match the expected values.
    DFD block #1 bytesPlanes in basic DFD block are 0 0 0 0 0 0 0 0 but for VK_FORMAT_R16G16B16A16_SFLOAT textures these must be 8 0 0 0 0 0 0 0.
Validating ./papermill/charlie/sheen.ktx2
Validation failed

error-6001: Mismatching dfdTotalSize and dfdByteLength. dfdTotalSize must match dfdByteLength.
    dfdTotalSize is 28 but dfdByteLength is 0 and they must match.
error-6015: Invalid colorModel in basic DFD block for RGB VkFormat.
    DFD block #1 colorModel in basic DFD block is KHR_DF_MODEL_UNSPECIFIED but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be KHR_DF_MODEL_RGBSDA.
error-6025: Invalid sample count in basic DFD block. The sample count must match the expected sample count of the VkFormat.
    DFD block #1 sample count in basic DFD block is 0 but for VkFormat VK_FORMAT_R16G16B16A16_SFLOAT it must be 4.
error-6021: Invalid bytesPlanes in basic DFD block. The values do not match the expected values.
    DFD block #1 bytesPlanes in basic DFD block are 0 0 0 0 0 0 0 0 but for VK_FORMAT_R16G16B16A16_SFLOAT textures these must be 8 0 0 0 0 0 0 0.
Validating ./papermill/lambertian/diffuse.ktx2

TBF, the .ktx2 files are unchanged after re-running prefilter.sh. So it's not surprising.

IMO it's a bug in how glTF-IBL-Sampler uses the ktx libs.

[JMLX42]

• Upstream PR to update KTX-Software to v4.3.2: https://github.com/KhronosGroup/glTF-IBL-Sampler/pull/33
• Upstream issue regarding ktx validate fails: https://github.com/KhronosGroup/glTF-IBL-Sampler/issues/34