GLTFExporter: Improve alphaMode support. #12692
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donmccurdy
changed the title
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| if ( material.alphaTest !== 0.5 ) { | ||
| if ( material.alphaTest > 0.0 ) { |
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I'll keep both comparisons > 0.0 && !== 0.5. The second one just to prevent writing the alphaCutoff = 0.5 as it's already the default value on the glTF spec.
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| gltfMaterial.alphaMode = 'MASK'; // @FIXME We should detect MASK or BLEND | ||
| gltfMaterial.alphaMode = material.opacity < 1.0 ? 'BLEND' : 'MASK'; |
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That should work for now, although mask and blending is something that probably should be improved on the glTF spec. For example if we have a material with opacity: 1 and transparent :true , and a transparent png, and no alphatest, it will enable blending on three.js too, instead of just masking.
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What would be the purpose of opacity:1 + transparent:true? Not sure I understand this example but please weigh in on KhronosGroup/glTF#1158 if you have suggestions. 🙂
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opacity: 1 && transparent: true will still use the alpha channel of the map (if I remember it correctly), if transparent: false it won't.
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Ok, updated to avoid writing the default value. Any changes to the glTF alpha coverage spec will take some time, so there's no need to wait for that. |
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Yep I agree, this should work with the current spec, we could come back to it once the spec is changed. |
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Thanks! |
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@fernandojsg perhaps we should do this, instead? if ( material.transparent ) {
gltfMaterial.alphaMode = 'BLEND';
} else if ( material.alphaTest > 0.0 ) {
gltfMaterial.alphaMode = 'MASK';
}See https://discourse.threejs.org/t/gltfexporter-changing-alphamode/5993/2. |
Handling a case for PNG textures where
transparent=falsebutalphaTest>0. @fernandojsg does this seem like a reasonable way to guess at MASK vs BLEND modes?Also pads the JSON chunk to 4-byte boundary to make the validator happy. (https://gltf-viewer.donmccurdy.com/ runs validation automatically now)Reverting the padding for now.