WestLangley

>I have a minor preference that targeted = false should be the default, although obviously this would be a breaking change. It's probably not advisable, then. If you are willing...

A few thoughts... `applyPrimaryGradingCDL()` does not belong in the tone mapping file, IMO. Color correction and grading is output-device-independent. But when we support HDR monitors, our tone mapping will be...

My understanding from the ACES Imaging Pipeline is the Look Modification Transform, which includes color correction/grading, is applied in Scene Referred Linear Space _prior_ to exposure and tone mapping.

@donmccurdy Many thanks for your work on this! >so I believe that's a practical place to convert to ACEScc and apply the CDL Perhaps the working color space is converted...

>I'm inclined to switch to the full per-channel CDL implementation and support that. Agreed!

Related #8354. I think it would be nice to have a diffuse material that exhibits retro-reflection at grazing angles. The moon has often been used as a canonical use case....

@06wj Thank you for this PR. But remember, this does not have to be a pixel-perfect calculation. It is OK for the bounding sphere to be conservative (i.e., oversized). Perhaps...

@06wj For example, the sphere center can remain at zero. Maybe it is sufficient to simply increase (double?) the radius to account for the worst-case center offset.

>By changing the center and rotation, the sprite may be far away from the origin ```js this.center = new Vector2( 0.5, 0.5 ); // should be between 0 and 1...

Even if centers outside [ 0, 1 ] are supported, I think the PR only requires changing the sphere radius. I think a sufficient radius can be computed given the...