Dispose geometry and material in SparkRenderer.dispose()

[ArisLiWind]

Summary

Fixes a GPU resource leak in SparkRenderer.dispose() by releasing the renderer-owned SplatGeometry created in the constructor.

Root cause

SparkRenderer constructs its own SplatGeometry:

const geometry = new SplatGeometry();
super(geometry, material);

That geometry is owned by the renderer instance, but dispose() previously released render targets, textures, workers, accumulators, and pager state without disposing the geometry itself.

Because SplatGeometry allocates both a position attribute and an index buffer, each create/dispose lifecycle could leave two WebGL buffers behind.

Fix

Store the constructor-created geometry as renderer-owned state and dispose it during SparkRenderer.dispose().

Regression coverage

Added tests to verify that:

• SparkRenderer.dispose() releases its internal geometry
• disposing a renderer does not dispose geometry assigned from outside
• dispose() is safe to call multiple times

Validation

• npm test
• npm run lint -- --reporter=summary

[mrxz]

Store the constructor-created geometry as renderer-owned state and dispose it during SparkRenderer.dispose().

There is no need to specifically keep track of the constructor-created geometry. Replacing the geometry of the SparkRenderer is not supported. You can simplify the dispose logic to just this.geometry.dispose(). For completion sake could you also dispose the material?

Also no need to include the unit tests in this PR. While ultimately we should have extensive tests covering things like this, the required bootstrapping isn't ideal.

[asundqui]

@mrxz this will already be covered by #413 right? If so should we close this PR?

[oscarlorentzon]

This is independent from #413 which disposes the Object3D, and as @mrxz mentioned we should remove the tests for now and simplify this to:

this.geometry.dispose();
this.material.dispose();

[asundqui]

I see, got it! @ArisLiWind how would you like to make these changes so we can merge the PR? We can also take over this PR and apply these finishing touches.

[ArisLiWind]

Thanks! Feel free to take over the PR and apply the remaining changes needed for the merge.@asundqui

[oscarlorentzon]

Took this over as discussed, thanks @ArisLiWind.

Simplified according to the discussion above and rebased on main to resolve the conflict with #413.

[oscarlorentzon]

Fixes #408

[oscarlorentzon]

@dmarcos This should be ready to merge.