Use getDrawingBufferSize to determine renderer size

[mrxz]

The rendererSize was retrieved using WebGLRenderer.getSize(target). However, this method returns the size in logical pixels, whereas the actual size in physical pixels is needed. Using getDrawingBufferSize resolves this issue and returns the correct value for High-DPI displays (when pixelRatio != 1) and during WebXR sessions (both with and without WebXR Layers)

The AVP specific workaround puzzles me a bit. Unless this was written against an old version of Three.js, the size should be kept in sync. So getSize() returning 1x1 would imply a 1x1 render target being created for WebXR, which would be entirely unusable. @dmarcos Could you verify that rendering on an AVP works with these changes and that the workaround is no longer needed?

[dmarcos]

Thanks so much. I’ll try later today when I have my AVP available.

[mrxz]

Here's an example that shows the difference it makes. Note that the effect is more pronounced in the image compared to when viewed on an actual high DPI display:

Splat source: https://note.com/steam_studio/n/ne9736d94f162 (using the cactus_splat3_30kSteps_142k_splats.compressed.ply file)

[asundqui]

@mrxz this is truly an amazing find! Thank you so much for digging in and really getting to the root of what was going on.

I tested your fix and yes can confirm it makes it sharper. I tested on Vision Pro and for me unfortunately that strange 1x1 size workaround was necessary to make it work. I tested Quest 3 and it works correctly with this workout. I've pushed the workaround to this PR.

@dmarcos I think we should merge this in, do you want to check my workaround on Vision Pro?

[dmarcos]

Awesome work! Thanks so much. @mrxz workaround acceptable for now? I’ll verify on AVP before release

[mrxz]

Thanks for confirming that the workaround for the AVP is actually still needed. Definitely a weird quirk of Apple's WebXR implementation. Ideally this will be fixed upstream, but in the meantime having this workaround is acceptable. I'm going to open an issue on the immersive-web/webxr repo as I'm not sure Apple is spec compliant here or not.

See: immersive-web/webxr#1410

[dmarcos]

Thanks so much!