Antialias MeshPhysicalMaterial transmission support

[takahirox]

Fixes: #21913

Description

This PR adds antialias MeshPhysicalMaterial transmission support with WebGLMultisampleRenderTarget.

Screenshot problem

A problem is that it works correctly on web browser but WebGLMultisampleRenderTarget doesn't seem to work correctly on Puppeteer.

I made screenshots of webgl_materials_physical_transmission and webgl_loader_gltf_transmission but transmissionSamplerMap looks black.

I also noticed that the existing webgl2_multisampled_renderbuffers screenshot right side (using WebGLMultisampleRenderTarget) is black.

Any ideas to resolve the problem?

[mrdoob]

@c0d1f1ed Does swiftshader support multisample render targets?

[c0d1f1ed]

@c0d1f1ed Does swiftshader support multisample render targets?

Yes, SwiftShader fundamentally supports multisample render targets. However, I'm not 100% sure if our legacy OpenGL ES implementation has all of the extensions expected by WebGL (I vaguely recall that the 'Core' multisampling functionality has potential restrictions, which are lifted by extensions such as GL_EXT_multisampled_render_to_texture).

However, we're about to replace the legacy SwiftShader OpenGL ES 3.0 implementation with SwANGLE (ANGLE + SwiftShader Vulkan), which fully supports OpenGL ES 3.1 and a larger set of extensions. You can give it a try with Chrome Canary using the --use-gl=angle --use-angle=swiftshader command line flags.

[mrdoob]

@c0d1f1ed Thanks! That is good to know.

Turns out the issue was that we were using a very old version of Puppeteer.
Updating to 10.0.0 seems to fix it: #21948

I've also tried --use-gl=angle --use-angle=swiftshader but seems to produce black renders.
Probably the version of Chromium that Puppeteer is using is not new enough?

[mrdoob]

Thanks!

[mrdoob]

@takahirox FYI cleaned it up a bit: 65e6b48