An invisible light source that can change and move over time. Its position can change and it can be aimed at moving objects. Dynamic lights are recalculated continuously, which means they have a higher processing cost but are much more flexible than static lighting. Use this type of light sparingly, because it is the most expensive light for the engine to render.
In a few cases it’s possible to make the texture itself appear bright or even to emit light. Doing so requires the use of a .vmt or .rad file and is beyond the scope of this article. Doing so can save the mapper the effort of trying to create an even lighting affect across a surface that’s meant to be the light source.
A normal light that lights only the particles created by an env_smokestack and lights nothing else. Useful for enhancing lighting in areas with steam and such but rarely used due its specific nature.
This is an entity used to specify the origin from which another entity is lit. Sometimes due to drastic changes in light over short distances or complex shadows a model can appear to be lit incorrectly. By using this entity the model will be lit as though it were stationed at this location.
One common example is the HL2 static Ladder props when used in dark areas they may appear to glow, which can be corrected by inserting an info_lighting, naming it and specifying that name in the properties for the Ladder prop.
Used to create a bright almost flare that will fade out at specified distances. Generally used to transition dark tunnels to bright outsides. Used as a precursor to the HDR effect to fake a change in exposure of the light.
This forces a particular brush face to not receive any of the dynamic shadows created by physics entities or NPC’s. It’s used rarely but may be needed to hide incorrect or bad shadows that create an artifical look.
Used to control the exposure of the HDR lighting effects. Unless used with fully implemented HDR it has little/no effect.
Used to smooth lighting between faces. Found in the face edit dialog, the groups allow the lighting of a face to be smoothed between other faces, to produce rounded effects with lighting. A classic example is when making a cylinder: If no smoothing groups are set, each face on the brush will catch light separately and will be lit separately. This will create a very obvious effect of separate each face. If they are all placed in the same smoothing group the light will be blurred between the faces creating a much smoother rounder look on the pillar. Taking no extra cost except for adding time to rad compiles they are an essential part to final lighting effects.
A lightmap is the lighting data of each face. The stored light is then added to the face giving it brightness. The lightmap's scale refers to the number of texture pixels per light pixel (luxel). Smaller values mean more luxels, thus a better quality but larger BSP size and compile times.