fix: pass mapped textures to onLoad callback in useTexture

[MichaelangJason]

Why

onLoad callback for useTexture is typed to accept MappedTextureType<Url>, which includes TextureRecord<Url>. However, onLoad is called with the raw output of useLoader, which is cast to MappedTextureType<Url> but will never actually be a TextureRecord<Url> (only _Texture[] or _Texture, respectively, TextureArray<Url> and SingleTexture<Url>). This means an onLoad callback expecting a TextureRecord<Url> would receive an array instead of a keyed object.

What

This PR moves the useMemo call before the useLayoutEffect, and passes the correctly structured mappedTextures to the onLoad call.

I noticed that the original useLayoutEffect didn't include textures in its dependency list. I assumed this was intentional to avoid re-firing onLoad unnecessarily, so I kept the same pattern and didn't include mappedTextures in the dependency list either.

Checklist

• Ready to be merged

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[travisbreaks]

The fix is correct — onLoad was receiving raw loader output instead of the mapped texture record. Moving useMemo above useLayoutEffect ensures mappedTextures is computed before the callback fires.

One note: the useLayoutEffect dependency array is [onLoad] but doesn't include mappedTextures. If the textures change (e.g., dynamic URL swap), onLoad won't re-fire with the new mapped textures unless the callback reference also changes. This matches the existing behavior before this PR, so not a regression — but worth noting for anyone expecting onLoad to fire on texture updates.

The fix itself is clean and minimal. LGTM on the core change.

[MichaelangJason]

The fix is correct — onLoad was receiving raw loader output instead of the mapped texture record. Moving useMemo above useLayoutEffect ensures mappedTextures is computed before the callback fires.

One note: the useLayoutEffect dependency array is [onLoad] but doesn't include mappedTextures. If the textures change (e.g., dynamic URL swap), onLoad won't re-fire with the new mapped textures unless the callback reference also changes. This matches the existing behavior before this PR, so not a regression — but worth noting for anyone expecting onLoad to fire on texture updates.

The fix itself is clean and minimal. LGTM on the core change.

@travisbreaks Thank you so much for the code review! Sorry for the late reply.

[MichaelangJason]

Hi @DennisSmolek !

Just following up on this PR whenever you have a chance to take a look. I’d really appreciate any feedback on whether these changes address the issue correctly, and specifically whether ⁠mappedTextures should be included in the ⁠useLayoutEffect dependency lists.

I noticed the project seems to be focused on v11, so I understand if this PR is lower priority at the moment. I took a quick look at the v11 code, and it seems these changes could likely be applied there as well without modification. If that would be more useful, I’d be happy to open a separate PR for v11 or retarget this one to it.

Since this is my first contribution to an open-source project, I’d also appreciate any guidance on the best next step.

Thanks for your time!