Shaders: Improve Packing

[WestLangley]

Fixed #28692.

This PR implements the improvements to packing suggested by @leonbloy in #28692.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

Filesize dev	Filesize PR	Diff
682.2 kB (169 kB)	683.4 kB (169.2 kB)	+1.26 kB

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

Filesize dev	Filesize PR	Diff
459.4 kB (110.9 kB)	460.6 kB (111.1 kB)	+1.2 kB

[Mugen87]

LGTM! Do you mind reverting the changes to three.module.js for merging?

[lmicola]

Any reason why this wasnt included in 167 milestone? It took me by suprise that my implementation of depth picking stoped working properly.

[Mugen87]

Not sure what you mean since the changes are part of the engine since r167.

[mrdoob]

@lmicola Do you mean in the change log?

[Mugen87]

It should be there:

[WestLangley]

Perhaps he is referring to r167 in the migration guide.

[lmicola]

I apologize. I thought that this PR was not included in change log. I think mention about RGBADepthPacking color output change in migration guide would be helpfull. I wonder if it is possible to make depthBuffer and reverseDepthBuffer color output uniform.

[WestLangley]

The RGBADepthPacking API has not changed, only the implementation. I am inclined to think it is not appropriate to include it in the r167 migration guide.

/ping @Mugen87