DepthTexture: Support texture depth comparison.

[RenaudRohlinger]

This PR introduces a compareFunction property to the DepthTexture class, enabling depth texture comparison.

This is the first step in order to improve the shadows in a WebGL2 context. This will allow implementing hardware anti-aliasing of shadow maps through depth comparison.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

Filesize dev	Filesize PR	Diff
634.8 kB (157.3 kB)	635.5 kB (157.6 kB)	+760 B

🌳 Bundle size after tree-shaking

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

Filesize dev	Filesize PR	Diff
425.7 kB (103.2 kB)	426.2 kB (103.4 kB)	+472 B

[RenaudRohlinger]

Updated the PR consequently, also I'm not sure about how to handle deserialized operations.

[Mugen87]

You can add the following new line:

 if ( data. compareFunction !== undefined ) texture. compareFunction = data. compareFunction; 

here:

three.js/src/loaders/ObjectLoader.js

Line 669 in 00a427c

if ( data.unpackAlignment !== undefined ) texture.unpackAlignment = data.unpackAlignment;

[LeviPesin]

I don't think it's a string?

[Mugen87]

b905e27

[WestLangley]

It's an integer, correct?. Also, the default should be specified in the docs.

Edit: It's null or an integer; hence, a number.

[RenaudRohlinger]

There isn't any default value as otherwise it would involve that the compare function is enabled by default.

[WestLangley]

The default is null. And the docs should explain the consequences of a null value.

[Mugen87]

Should be fixed via 43c701c.