GTAONode: Implement composite.

[Mugen87]

Related issue: #28844

Description

This PR implements a basic composite for GTAONode so the AO is blended to the beauty pass.

A simple GUI in the example allows to change the AO blend intensity.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

Filesize dev	Filesize PR	Diff
683.5 kB (169.2 kB)	683.5 kB (169.2 kB)	+0 B

🌳 Bundle size after tree-shaking

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

Filesize dev	Filesize PR	Diff
460.7 kB (111.1 kB)	460.7 kB (111.1 kB)	+0 B

[Mugen87]

We might want to make GTAONode a bit more flexible so it reports the raw AO (without the composite). In this way, the dev can to blend the AO with a custom function or even apply a custom blur before doing the blend.

[Mugen87]

Current progress:

Previous GTAO with EffectComposer: Beauty, Normal + Depth, AO, Blend, Output: 5 Passes
New GTAO with PostProcessong: Beauty + Normal + Depth (via MRT), AO, Blend + Output (merged thanks to node material): 3 Passes

The denoise pass is still missing but we can maybe make this step configurable so if you don't need best quality you get a bit more performance. I'll do that next.

[sunag]

I made some changes to this PR, I think it's important to keep getTextureNode() for external manipulation level, like adding a custom Denoise filter or just a blur without having to do a new render-pass.

I'm removing blendIntensity too, now with TSL I think it's better that this level of abstraction stays outside the internal Nodes, intensity, blend are things that would only bring more load to the examples since we could use blendIntensity.mix( beauty, beauty.mul( ao ) externally if necessary.

[sunag]

Yeah, you think the same think <3 #28851 (comment)
I'm reading the comments now :)

[Mugen87]

I'm fine with your suggested changes. I've only added blendIntensity now so the implementation can be considered as "complete" and usable in apps.