Outdoor lighting and fake G.I. in Quake with examples.

Had some more experiments with outdoor lighting in Q1BSP using Tyrlight  and here are the examples and explanation for those who might be new to this.

Usually you light an outdoor scene by using a sunlight (“_sunlight” “n” worldspawn key) which is cast from sky brushes at some angle (defined by “_sun_mangle” “x y 0” worldspawn key, where “x” is angle around the Z-axis  from 0 to 360 and “y” is the pitch angle from 90 = up to -90 = down). And to light everything not hit by sunlight a global minlight ( “light” “n” worldspawn key) is often used – which only rises a minimum value. It is very quick to set up but looks super dull and absolutely flat.

Alternatively you can try to fake global illumination (GI) using about a dozen of  local minlights: small value (~10~20) point lights with “delay” “4” or “3”  key (infinite cast range) and evenly place them all around your scene near the sky. It’s a well-known trick sometimes used in 3d graphics. Doesn’t take long to set up, faster to compute than true GI/radiocity and gives good results.

But if you simply use “delay” “4” lights it still looks very flat, especially from the side not lit by sunlight, because the lights only rise the minimum level, not adding up. (sunlight in this example was increased to compensate for the lack of additive lights)

 

With “delay” “3” lights  you get far better results with prominent shadows but still kinda flat:

  

And the best and most realistic look is achieved by using “delay” “4” lights but compiling with -addmin command line option. It makes allthe minlights additive resulting in smooth gradient shading with shadows and even highlights, resembling diffused lighting/radiocity/GI in more advanced compilers and light renders:

 

And of course don’t forget to use -extra4 -soft 1 command line options  for the maximum quality of lightmaps.
TyrLight by  Kevin Shanahan (AKA Tyrann)  http://disenchant.net/utils/  It has documentation that lists and explains all the options and parameters, if something is unclear.
I hope this was useful and we’ll never see maps with just sunlight/minlight.

fake GI with tyrlight

Old trick faking Global Illumination by using several small value but infinite range lights at every side of a skybox (or around skydome).
“delay” “3” lights in case of quake light compiler like Tyrlight

EDIT: After some experiments found out that “delay” “4” ambient lights compiled with -addmin (which makes minlight additive instead of just floor value)  option produce best looking result.

Fun with Darkplaces

It’s probably good to write down some stuff that I discover on the way, so here it goes.

Darkplaces combines lightmaps to speed up rendering.
Q1 compilers match lightmap scale with texture scale.
So if a map uses rescaled textures the combined lightmaps are applied wrongly (and notice that the wall is rescaled, not the wood) . Something to keep in mind… and hopefully a fix or switch will be implemented.

 

Also gl_lightmaps 1 is pretty handy and cool looking.