WestLangley

The `PMREMGenerator.html` document appears to be a bit out-of-date and should probably be updated for clarity. Perhaps the size limitations can be added there, too.

In what coordinate frame is the background Euler rotation applied? I assume you intend it to be the three.js right-hand coordinate frame. In the shader, the coordinate frame is left-handed....

Do you intend to add support for rotating `scene.environment`?

The reflections and rotations are not correct. I'll file a PR in an attempted fix. Unfortunately, getting these calculations correct has taken considerable effort...

For further reference, see [Unity's implementation](https://github.com/Unity-Technologies/Graphics/blob/4346b019f9e1feae60359a07b5fb38f11ad88251/Packages/com.unity.render-pipelines.high-definition/Runtime/ShaderLibrary/FrustumCulling.hlsl#L39).

I am inclined to think this approach gets away from the original intent of making the lights "just work". See the discussion [here](https://github.com/mrdoob/three.js/issues/7690#issuecomment-160186083.).

>It should be mentioned that also with the classical materials it is already possible to do this by setting material1.envMapIntensity = 0.5 and material2.envMapIntensity = 2.0 (i.e. different scaling factors...

I think what you said is correct, and I don't think it is contrary to my statement. 🤔

Friendly tip. `MeshPhysicalMaterial` requires an environment map. I used `RoomEnvironment` here, but it is your choice. Scene lights are not required. I set material color to white, metalness 0, roughness...

Oops. `SVGLoader()` uses these methods extensively...