Support Other Textures in GLTFLoader

hjlld · November 29, 2019, 12:28pm

I use Basis texture compression format to replace all png textures, and replace all ‘.png’ to ‘.basis’ inside gltf file.

glTFLoader.js

github.com

BabylonJS/Babylon.js/blob/11263f1393cab2e5691b5874a83392a2520b6994/loaders/src/glTF/2.0/glTFLoader.ts#L1889




const sampler = (texture.sampler == undefined ? GLTFLoader._DefaultSampler : ArrayItem.Get(`${context}/sampler`, this._gltf.samplers, texture.sampler));
const samplerData = this._loadSampler(`/samplers/${sampler.index}`, sampler);


const image = ArrayItem.Get(`${context}/source`, this._gltf.images, texture.source);
let url: Nullable<string> = null;
if (image.uri) {
    if (Tools.IsBase64(image.uri)) {
        url = image.uri;
    }
    else if (this._babylonScene.getEngine().textureFormatInUse) {
        // If an image uri and a texture format is set like (eg. KTX) load from url instead of blob to support texture format and fallback
        url = this._rootUrl + image.uri;
    }
}


const deferred = new Deferred<void>();
const babylonTexture = new Texture(url, this._babylonScene, samplerData.noMipMaps, false, samplerData.samplingMode, () => {
    if (!this._disposed) {
        deferred.resolve();
    }

this._babylonScene.getEngine().textureFormatInUse seems to be undefined in my case, any way .basis is actually not in this supported list as well as Engine.texturesSupported.

maybe line 1889 here should be else but not else if, leave Texture class to handle texture loading.

sebavan · November 29, 2019, 12:32pm

textureFormatInUse is not something which should be defined by default. It is only here in case you want to replace any texture call with ktx, I do not think it is that simple to repurpose to basis.

Ping @bghgary for ideas

hjlld · November 29, 2019, 12:51pm

KHR_texture_basisu, KHR_image_ktx2 are still experimental, but actually we can use various unusual formats in GLTF by setting up image.uri.

the way i described is making Texture class handle properly image.uri from gltf file.

sebavan · November 29, 2019, 12:53pm

Could you submit a PR for it so that @bghgary can review after thanksgiving ?

hjlld · November 29, 2019, 12:54pm

Sure, there’s no hurry.

bghgary · December 2, 2019, 6:28pm

I’m not a big fan of this part of the code. IMO, the glTF loader should not explicitly allow non-core spec code paths. I will gladly review a PR, but it might be better to put this under a loader extension or at least a flag.

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Support Other Textures in GLTFLoader

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