glsl ifdef generator does not set define anytime

[illwieckz]

See #189 for a branch that reproduces the bug (you need Xonotic assets since Unvanquished ones run the code used when the define is not defined).

It looks like the define is not defined any time as while I move in map, the wrong code is sometime run instead of the expected one:

The bug is on the wall texture, not on the blooming reactor.

I understand nothing from the define generator code and I need help to fix it, or someone who understands it to fix it himself.

[illwieckz]

If I understand it right, the code computes a program index for each shader variation, so it can switch to one of those program per texture within one frame. I guess the issue is that the index computation gets some collision.

[illwieckz]

OpenGL swizzle mask may allows us to not require the usage of defines to discriminate normalmap shipping heightmap or from one not shipping height map, it would also allow use to add support for loose heightmap without requiring a complicated glsl code.

Basically, I think about this:

if normalmap:
	if heightmap in normalmap:
		set normalmap.rgba as normalmap
		set normalmap.aaa0 as heightmap
	else
		set normalmap as normalmap
		if heightmap:
			set heightmap as heightmap
elif heightmap:
	set dummynormalmap as normalmap
	set heightmap as heightmap

That would require OpenGL 3.3. The game would still work for older hardware without OpenGL 3.3 support but with normalmap and heightmap support being disabled for normalmap files shipping heightmap.

Complete bind code would be:

if normalmap:
	if heightmap in normalmap:
		if GL_ARB_texture_swizzle or GL_EXT_texture_swizzle:
			set normalmap.rgba as normalmap
			set normalmap.aaa0 as heightmap
		else:
			set dummynormalmap as normalmap
			set black as heightmap
	else
		set normalmap as normalmap
		if heightmap:
			set heightmap as heightmap
elif heightmap:
	set dummynormalmap as normalmap
	set heightmap as heightmap
else:
	set dummynormalmap as normalmap
	set black as heightmap

Note: if we implement normalmap from heightmap when there is no normalmap, we may bind black as normalmap and compute normalmap when normalmap is pitch black.

[illwieckz]

I'm not sure there is a bug in that ifdef code, similar artifact can happen with zero normalscale (hence undefined normalscale). I noticed some issues with that other feature, so maybe it's the same. Closing it for the moment.

Also, the shader dump shows the define properly, so I'm more suspicious about undefined normalscale.