MMDLoader: Skip transparency check for CompressedTexture.

[bill42362]

Related issue: #17974

Description

I got this similar error when load MMD model with .dds texture:

MMDLoader.js?aed8:1456 Uncaught TypeError: Failed to execute 'drawImage' on 'CanvasRenderingContext2D': The provided value is not of type '(CSSImageValue or HTMLImageElement or SVGImageElement or HTMLVideoElement or HTMLCanvasElement or ImageBitmap or OffscreenCanvas or VideoFrame)'
    at createImageData (MMDLoader.js?aed8:1456)
    at Array.eval (MMDLoader.js?aed8:1524)
    at eval (MMDLoader.js?aed8:1406)
    at Object.eval [as onLoad] (three.module.js?5a89:35025)
    at XMLHttpRequest.eval (three.module.js?5a89:34742)

And I found if there's data property inside image object, MMDLoader:L1316 would just use it to check transparent, which could bypass process to get image data via <canvas>.

First time to make PR to opensource projects, hope this could help.

[Mugen87]

I think this problems should be solved in MMDLoader instead.

I also doubt that detectImageTransparency() will work with a compressed texture.

[bill42362]

@Mugen87 Thanks for your comment!

I've change the fix into MMDLoader, but I don't know better ways to check transparency of compressed textures.
So it's just a quick fix, which only set transparent to false for non-alpha channel formats.

[takahirox]

Yes, as @Mugen87 mentioned I don't think detectImageTransparency() works for compressed texture. So this workaround looks good to me (for now). Thanks!

[mrdoob]

Thanks!