Light Textures and Falloff Images

Introduction

While The Dark Mod comes with a rich library of Light Shaders and Textures there are times when mappers may wish to customize the look of lighting further. Light Textures can be used for basic light painting tricks like projecting window-panes light on a floor to advanced uses like simulating the look of a baked light-map.

Lunaran (Matthew Breit) did an in depth look and the performance aspects of Light Shaders in Id Tech 4 and found that there is no performance loss for applying falloff Images and light texture to all lights on your map. He used this new-found insight to develop a technique for making the most of light textures. Essentially he took screen-shots from specific views of his map where light volumes affected the geometry in a predictable way and then painted light textures that conform to the contours of the space and surfaces shown in the screen-shots.

Lunaran's method involves not only shaped point and omni lights but also a shaped ambient (that is the deluxe method). Even without shaping the ambient a couple of custom-textured point lights can give you much richer lighting that the standard squares and circles that are commonly used.

Step 1 Planning

Once you have your map or map section built you will need to decide what lights will be direct and where you might want bounced light or moonlight to hit your geometry. If you have placed lights all over the place to approximate these bounced effects then you will need to pare-down some lights.

Placeholder References:

Works with the Light Gem.

Example Light Shader

lights/aa_1_sky1

{

lightFalloffImage makeIntensity( gfx/lights/1_sky1_z.tga )

{

forceHighQuality

map gfx/lights/1_sky1_xy.tga

red Parm0 * 2

green Parm1 * 2

blue Parm2 * 2

zeroClamp

}

}

Example Ambient Light Shader

lights/aa_1_amb1

{

ambientLight

lightFalloffImage makeIntensity( gfx/lights/xrampup.tga )

{

forceHighQuality

map gfx/lights/1_amb1_xy.tga

colored

// zeroClamp

}

}

Sub-Directories

Materials, Lights, LightsShadows, TexturesLights

Look in tdm_textures_base01 tdm_light_shadows tdm_light_textures

Links and References

Light Baking Thread:

http://modetwo.net/darkmod/index.php?/topic/11416-light-baking/

Strombine:

http://www.lunaran.com/page.php?id=165

Strombine at Quake3world:

http://www.quake3world.com/forum/viewtopic.php?t=29872