Added color correction using LUT texture to CameraFrame postprocessing

[mvaligursky]

Fixes #4315

Added color lookup to CameraFrame postprocessing. Live preview: https://engine-pso3eqdcf-playcanvas.vercel.app/#/graphics/hdr

New API

    cameraFrame.colorLUT.texture = texture;
    cameraFrame.colorLUT.intensity = 1.0;

Texture is a common .cube format stored in a horizontal strip

There are multiple free online tools to convert to this format. I used https://www.color.io/free-online-lut-converter - loaded a cube file, and exported to Cube Strip 2D.

This is also exposed in the CameraFrame.mjs script, but at the moment does not parse correctly. @marklundin is investigating.

lut.mov

[willeastcott]

Isn't this just a new tonemap type? Like, maybe, TONEMAP_LUT or TONEMAP_TEXTURE?

[mvaligursky]

Isn't this just a new tonemap type? Like, maybe, TONEMAP_LUT or TONEMAP_TEXTURE?

Tone map converts HDR -> LDR. The look up works on LDR, so it cannot be used instead of tonemap, but along with it.

[Maksims]

In the example, should the LUT texture filtering be set to "nearest"?

[mvaligursky]

In the example, should the LUT texture filtering be set to "nearest"?

It needs to be linear, which it is. Otherwise you get banding due to relatively low resolution (32 pixels)

[mvaligursky]

Script works now as well: