posted 02-11-2004 05:24 PM           

I wanted to test the resulting differences that certain Q3Map2 specific shader keywords had on a map illuminated by a single source of light eminating from the sun shader. The goal was to test several different changes, one at a time, in comparison to a map compiled with a sky shader emulating pre-Q3Map2 lighting. By comparing screenshots, we can determine where quality improves and perhaps where there may be limitations.

To keep things constant, the same map was compiled with very basic LIGHT switches, -fast is the only switch used (probably shouldn't have used -fast at all but got tired of waiting). The screenshots were all taken from the exact same direction and angle for easy comparisons. All other parts of the shader were kept the same except for certain q3map_* keywords being tested. The screenshots were all taken with "/cg_drawgun 0", "/cg_draw2d 0" and "/r_lightmap 1". The _lightmapscale was lowered in the worldspawn to 0.125. The sky textures were taken from ydnar's "shaderlab_terrain" sample map. The shader was modified from the same map.

This is the base shader used for testing. Note the section where I placed the variables being tested:

code:

---

textures/shadermanual/sky
{
	skyparms textures/shaderlab_terrain/env/sky 1024 -	
	q3map_lightImage textures/shaderlab_terrain/sky_clouds.tga
	//*** VARIABLES START ***
	...
	//*** VARIABLES END ***
	surfaceparm sky
	surfaceparm noimpact
	surfaceparm nolightmap
	surfaceparm nodlight
	nopicmip
	nomipmaps
	qer_editorimage textures/shaderlab_terrain/sky_clouds.tga
	
	{
		map textures/shaderlab_terrain/sky_clouds.tga
		tcMod scale 3 3
		//tcMod scroll 0.005 -0.0125
		rgbGen identityLighting
	}
	{
		map textures/shaderlab_terrain/sky_arc_masked.tga
		blendFunc GL_ONE_MINUS_SRC_ALPHA GL_SRC_ALPHA
		tcMod transform 0.25 0 0 0.25 0.1075 0.1075
		rgbGen identityLighting
	}
}

---

The first screenshot emulates a pre-Q3Map2 shader using...

q3map_sun 1 1 1 140 -35 25
q3map_lightSubdivide 256
q3map_surfaceLight 200

... This is the kind of results that you would get using default Quake III Arena shaders. Following that, are the screenshots taken as I made various changes, one at a time, to the above options. The changes made are listed in the top left corner of the screenshots and you can see the resulting differences.

#01
#02
#03
#04
#05
#06
#07
#08
#09

One thing that I didn't record was the quantitative differences in LIGHT compile time between different changes in the shader. I had too many different applications running simultaneously for any accurate measurements anyway. Qualitatively however, I did notice a large reduction in compile time by replacing q3map_lightSubDivide (and q3map_surfacelight) with q3map_skylight (approximately from 80 sec. to about 10 sec.). Other keywords like q3map_lightmapFilterRadius obviously increased compile times somewhat.

What I'd like to see are some other compiles and experiments using this same map. I think it would be interesting to see what kind of results different people can come up with. Some additional things to try may include using different compile switches and different shader keywords. I'd like to see this as an open discussion on how lighting quality can be improved.

The map file is available here (smapi.zip - Shader Manual APpendix I): http://members.lycos.co.uk/quakeroats/samples/

------------------
Q3Map2 Shader Manual

posted 02-11-2004 06:05 PM          

One thing to keep in mind is that q3map_lightmapFilterRadius must be *before* any light-related directives that you want it to affect.

You could, for instance have two seperate entries, one before the sun to blur it 8 units, and one before the skyLight, to blur it 64 units.

posted 02-11-2004 06:32 PM           

What's the first parameter for? I tried setting it to different values but only a value of 1 caused a noticable difference.

I'm guessing that the second parameter is the radius at which filtering occurs, but where is the radius measured from?

Edit: BTW ydnar, may I see your Cornell Box sample map. I'd like to compare it with this and see what I can do with the lighting.

posted 02-11-2004 06:58 PM          

Where :self: and :other: are world units of filtering (blurring) of lightmap data cast by any lightsources defined following.

The first value is always zero on sky shaders (they don't have lightmaps). The second value is usually high enough to eliminate the "statium shadow" effect of q3map_skyLight. If you use values higher than 4 on the 2nd value of q3map_skyLight (iterations) then you don't need to use q3map_lightmapFilterRadius as much. It's more of a quick hack to approximate finer subdivided sky lighting.

y

posted 02-11-2004 07:25 PM          

This one has shadows coming from multiple light sources and seems to be undesireable unless your level is set on a planet with multiple suns.

posted 02-11-2004 08:39 PM          

quote:

---

Originally posted by Kat: slightly OT : I don't know about anyone else but this *really* highlights the blood, sweat & tears ydnar has put into q3map2, so big thumbs up to ydnar and Co.

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posted 02-11-2004 09:26 PM           

quote:

---

Originally posted by Boot Louie: Here here!!!

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Hear hear !!

posted 02-12-2004 09:08 AM          

Fast, good quality (brightness values are tweakable):

q3map_sunExt 1 1 1 140 -35 25 2 8
q3map_lightmapFilterRadius 0 32
q3map_skyLight 80 3

High quality (final compile):

q3map_sunExt 1 1 1 140 -35 25 2 32
q3map_skyLight 80 6

Note the replacement of q3map_lightmapFilterRadius with more skyLight iterations, and more sun samples.

posted 02-12-2004 09:20 AM          

quote:

---

Originally posted by Kat: slightly OT : I don't know about anyone else but this *really* highlights the blood, sweat & tears ydnar has put into q3map2, so big thumbs up to ydnar and Co.

---

posted 02-12-2004 03:17 PM           

quote:

---

Originally posted by ydnar: Fast, good quality (brightness values are tweakable): q3map_sunExt 1 1 1 140 -35 25 2 8 q3map_lightmapFilterRadius 0 32 q3map_skyLight 80 3 High quality (final compile): q3map_sunExt 1 1 1 140 -35 25 2 32 q3map_skyLight 80 6

---

These two screenshots are based on your set of parameters.

#10
#11

Same as the second one, except with q3map_lightmapFilterRadius 0 8
#12

I'm curious on people's opinions about these, which screenshot do you think looks the best?

posted 02-12-2004 03:27 PM          

edit: the more i switch between 2nd and 3rd the more i like the 3rd actualy

posted 02-13-2004 02:57 PM          

This page is saved down to here. Well worth the drive space.