Export Babylon scene to GLB/GLTF always turns textures into .png format

Questions
1

Hi, I have been experimenting with exporting my scenes as GLTF/GLB, and it seems like every texture I have imported automatically gets turned from a .jpg into a .png, increasing the total file size of my export significantly.
Is there a way to get around this?

Basic repro: https://playground.babylonjs.com/#20OAV9#9730
It loads a JPG, but exports and downloads a PNG.

2

The only way to chose your mimeType would be to prevent any kind of texture conversion so use a PBR Material, and a metallic workflow. Then you would need to force a chosen mimeType on the texture upon creation to conserve it.

3

Thanks, this seems to work in this case.
Is it also possible to define the mimeType on an AssetManager’s TextureAssetTask (TextureAssetTask | Babylon.js Documentation)?
Playground: https://playground.babylonjs.com/#20OAV9#9733

4

I do not think so but you might force it through _mimeType after loading ? if that works we ll try to find a proper way to fill it in.

5

The following indeed works:

const textureTask = assetsManager.addTextureTask("woodTex", url);
textureTask.onSuccess = function (task) {
    const texture = task.texture;
    texture._mimeType = "image/jpeg";
    wood.albedoTexture = task.texture;
};

Alternatively I got it to work by loading it as a binary file first:

const binaryTextureTask = assetsManager.addBinaryFileTask("woodTexBinary", url);
binaryTextureTask.onSuccess = (task) => {
    const tex = new BABYLON.Texture(task.url, scene, undefined, undefined, undefined, undefined, undefined, undefined, undefined, undefined, "image/jpeg");
    wood.albedoTexture = tex;
}

Thanks for your help!

Full playground with both tests: https://playground.babylonjs.com/#20OAV9#9740