GtkRadiant Editor Manual

Tools 6: Lights & Lighting

Lighting a map is both an art and a science. For Quake III Arena, the id designers worked to create instances of dramatic lighting, while attempting to maintain a relatively consistent intensity of light throughout the maps. Other designers worked to create dark realms, full of shadows in which lurking assassins could hide.

Whatever style of lighting you strive for, remember one key rule: The bots don't use light information. In a pitch-black room, they would still see an opponent. Keep that in mind when designing your maps.

Entity Lights
There are several ways to create light emitting objects.  The simplest is to place a light entity into your map.  If you do nothing, it has a default value of 300 and emits white light. If you think of the light value as the wattage for an incandescent light bulb, you are not far off target. The section on the Light entity in the Entities Description Appendix contains specific information on using light entities.

Texture Lights
Textures can be made to emit light. The amount of light that they give off is determined by two factors: the size of the texture and the value given for its q3map_surfacelight parameter.

If you only plan on using id textures in your maps, simply use the textures surrounded by a white box in the texture window. Many of them have their light values as part of their names: Example: ceil22a_5k.  This would be a small, square light with a light value of 5000.  There is not a direct correspondence between the light value of a texture light and an entity light.

If you want to make your own lights, either with new, custom textures, or changing the light and/or color values of the emitted light in existing id textures, plan on learning your way around the shader files.  The Shader Manual explains the light commands. Place the new lights in unique directories. Example: Mymapname_light\skull_light_2k.  Use the q3map_editorimage key to make multiple light intensity versions of your new lights.

Generally speaking, very small lights need to have very large values to look right (a 32x32 pixel light could easily have a surfacelight value of 10,000 or more).  As the surface area of the light becomes larger, the amount of light needs to be substantially reduced for it to look right in the world.  A word of warning, though. Very large glowing surfaces (other than skies) can look odd in the game world, especially if they are made from a repeating texture.  The light source will appear to be generated from the center of the brush with the glowing texture.

"Sky" Lights
Quake III Arena was designed so that sky textures could appear to emit light in a natural way. The q3map_sun parameter creates a single light source in the sky. The mapper can control the brightness, color, and position in the sky of this light source.  Furthermore, the designer can add a q3map_surfacelight value to the sky, giving it an overall lighting value.

Ambient Light
Ambient light is a property of the map's worldspawn entity. By assigning a number value to the ambient key, the overall lighting level of the map is raised. This has the tendency to flatten the difference between light and shadow. The color of the light can also be modified. This technique is considered a "hack." It does not come recommended. You will find instructions that are more complete later in this manual under the worldspawn entity heading in the Entities Appendix.

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