Problem with Draco and unnormalized vertex colors

[lilleyse]

Draco encoded attributes whose accessors set normalized : true are not being normalized correctly during rendering, leading to overblown colors in the second image.

The decoder checks for attribute.normalize(), but maybe it should use the accessor's normalized property instead. Right now it doesn't seem possible in the Draco API to set whether an attribute is normalized, so attribute.normalize() will always be false.

A separate problem is the second gltf only works if dequantizeInShader is false.

vertex_colors.gltf.txt
vertex_colors_draco.gltf.txt

[ptrgags]

This problem might be relevant to ModelExperimental too, though not entirely sure. instead of washed-out colors, I get everything red:

Local Sandcastle -- note I'm on a local branch, I'm working on addressing #9956

[javagl]

Some of the issues that have been mentioned here also seem to be one of the root causes of https://community.cesium.com/t/failed-to-load-draco-compressed-gltf-file/32518 (for example, the fact that everything is rendered in 'red'...)

[ggetz]

Fixed with #12417.