It is hard for me to debug something because the inspector is not working, nor Spector as I must start in an anonymous window…
I really think it is the fact that we added support for sRGB buffers in the glTF loader, as it is new in alpha-23.
SceneLoader.OnPluginActivatedObservable.addOnce(function (loader) {
if (loader.name === "gltf") {
loader.useSRGBBuffers = false;
}
});
should disable this support, but to be sure you should check with Spector that the textures are not sRGB textures.
Not doing loader.useSRGBBuffers = false should/will definitely make a difference with the default setting (loader.useSRGBBuffers = true) because with the latter, the textures flagged with nonColorData=false (all by default) will be loaded in sRGB buffers, which means no gamma to linear space conversion should take place because the sampling from these buffers already returns linear values.
What would help is a link to a working sample with loader.useSRGBBuffers = false; so that I can start the inspector / Spector and see what’s going on.