cesium-native Add support for WebP images

Currently we're using stb (via tinygltf) for image decoding, but it doesn't support every format. Most notably missing is WebP. We should add support for this format for images inside glTFs and as raster overlays.

Dec 11 '20 00:12 kring

@shehzan10 @kring any idea what is driving the priority for this? Is EXT_texture_webp widely used?

Dec 18 '20 00:12 pjcozzi

@pjcozzi I was under the impression ion commonly produces tilesets with WebP images, so the motivation is just making sure ion's output (at least for meshes) is well-supported in Cesium for Unreal.

Dec 18 '20 01:12 kring

I was under the impression ion commonly produces tilesets with WebP images,

Sounds good if that is the case. @shehzan10 is it?

Otherwise, let's put our eggs in the KTX2 basket when ready.

Dec 18 '20 01:12 pjcozzi

Sorry I completely missed replying to this earlier.

WebP is certainly not the most common format by any means. As photogrammetry would be a large part of the streaming to Unreal, my reasoning was that it could form a part of "Optimize for Unreal" options on Cesium ion.

That said, launching without it wouldn't raise any eyebrows either. We'll evaluate this vs key requested features like picking.

Dec 21 '20 14:12 shehzan10