talk: liquid shader syntax design

[illwieckz]

This is the historic XreaL liquid shader design:

textures/test-water_custom/water
{
	qer_editorImage textures/test-water_custom_src/water_d
	qer_trans .6

	surfaceparm nobuild
	surfaceparm trans
	surfaceparm water
	surfaceparm nonsolid

	{
		stage liquidMap
		map textures/test-water_custom_src/water_n

		scroll time * .1, time * .1
		scale .5, .5
		refractionIndex 1.3
		fresnelPower 2
		fresnelScale .85
		fresnelBias  .05
	}
}

There is problems with that design: there is no fallback if liquidMapping is disabled, and we can't feed diffusemap to tint with colors, and we can't feed material map that may tweak reflectance.

My proposition is that:

textures/test-water_custom/water
{
	qer_editorImage textures/test-water_custom_src/water_d
	qer_trans .6

	surfaceparm nobuild
	surfaceparm trans
	surfaceparm water
	surfaceparm nonsolid

	{
		<keyword> liquidMap
		diffuseMap textures/test-water_custom_src/water_d
		normalHeightMap textures/test-water_custom_src/water_nh
		physicalMap textures/test-water_custom_src/water_orm

		scroll time * .1, time * .1
		scale .5, .5
		refractionIndex 1.3
		fresnelPower 2
		fresnelScale .85
		fresnelBias  .05
	}
}

If liquidMapping is disabled, the code would fallback to lightmapping shader instead (which does not look bad when using normal maps etc.). It would be better to merge liquid shader with lightmapping shader to achieves this.

[VReaperV]

The current liquid and lightMapping shaders are different enough that it makes sense to keep them separate. Other than that this is reasonable.

[VReaperV]

I don't get what the change from stage liquidMap to <keyword> liquidMap is supposed to accomplish though, or what <keyword> even is.