WebGLRenderer: Fix equirect texture conversion.

[Mugen87]

Fixed #20043 (comment)

When you load an equirect texture, WebGLCubeMaps will return null if the texture is not loaded yet. When the loading process is completed and the cube map was created, an update of the shader program is required. This missing bit was responsible for the uniform location errors.

[Mugen87]

webgl_loader_gltf is broken. Investigating...

[Mugen87]

Okay, should be fixed now!

I actually like the simplifications in WebGLMaterials^^.

[Mugen87]

Unfortunately, there is no way around this check. However, if an existing cube map is changed with another one, initMaterial() will not trigger the expensive shader compilation (unless mode, encoding or mapping is different).

[WestLangley]

@Mugen87 Thank you for helping with this. :-) After preliminary testing, everything appears to be working correctly for me.

[mrdoob]

Thanks!

[WestLangley]

@Mugen87 Git bisect is pointing to this commit... Are you able to reproduce it?

[mrdoob]

@WestLangley is this a continuation of a conversation from somewhere else?

[Mugen87]

Ah, I see what @WestLangley means. The sphere should have the same env map like the background.

[WestLangley]

@WestLangley is this a continuation of a conversation from somewhere else?

It was a follow-up to my previous comment where I said:

@Mugen87 Thank you for helping with this. :-) After preliminary testing, everything appears to be working correctly for me.

I was not sure if it actually never worked, or broke subsequent to testing...