Lighting

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Guides

• Adding Light - A beginners tutorial on how to set up a basic light entity.
• Intermediate Lighting - A tutorial dealing with all the light sources in more detail.
• Advanced Lighting
• Constant-Linear-Quadratic Falloff - An easy-to-read explanation of the old C-L-Q light attenuation system.
• HDR - High Dynamic Range Lighting.

Entities

Static light sources

light

A static, omni-directional point light source. (e.g. a naked light bulb or flame.)

light_spot

A static, uni-directional point light source. (e.g. a torch) The conical beam angle cannot exceed 90°.

light_environment

Provides two linked light sources; a "Diffuse light" reflected from overhead clouds/sky and a "Parallel light" which represents sun- or moon- light. Both are emitted from the toolsskybox material wherever it is used on a map. See also Skybox.

env_particlelight

Illuminates particles produced by env_smokestack. Particles are not affected by normal lighting. Use (no more than) two of these to make (only) env_smokestack particles appear to reflect ambient lighting.

luminous materials

Brush surfaces with a light-emitting material (as defined in game_dir/lights.rad) applied will cast volumetric light in a 180° cone.

Dynamic light sources

light_dynamic

A simple, uni-directional dynamic light that can be moved, turned, and adjusted.

point_spotlight

A dynamic spotlight beam effect, with an optional dynamic light source where it hits a surface.

npc_spotlight

A spotlight NPC, similar to point_spotlight but with the capability of tracking targets.

env_projectedtexture

A dynamic light that lights using a texture rather than a solid colour, and which also casts realistic dynamic shadows. Affects all surfaces that can accept lighting, and is used for the player flashlight in Episode Two.

Shadows

• Static Shadows are cast only by the combination of static light sources and static geometry (Brushes and Models); they are calculated and baked into the Lightmaps by VRAD, so they look much better and are relatively cheap to render.
• Dynamic Shadows are cast only by World Models (NPCs, phys-props, etc), and only onto Brush surfaces (from both Static and Dynamic light sources). They are calculated at runtime, so they are quite crude and relatively expensive to render.

• Sometimes (?) Dynamic Shadows are projected through walls and floors, giving away the location of enemies. Use info_no_dynamic_shadow to workaround this problem.
• Dynamic Shadows do not coagulate with each other or with Lightmapped shadows when they overlap. For example, light_environment casts both Static and Dynamic Shadows, so use info_no_dynamic_shadow to prevent 'shadows within shadows' from a single light source.

shadow_control

Point entity used to control Dynamic Shadow projections for the entire map.

info_no_dynamic_shadow

Point entity used to list Brush surfaces that should not receive Dynamic Shadows.

Lightmap Scale

Hammer Face Edit Dialog tool used to define how sharp/diffuse the Static Shadows will be on individual Brush surfaces. See also the shadow_control Entity's "distance" parameter for diffusion of Dynamic shadows.

prop_physics entities 

have a "shadowcastdist" keyvalue to override how far this object casts Dynamic Shadows.

prop_dynamic entities 

have a "disableshadows" keyvalue, and "enableshadows" and "disableshadows" inputs to control Dynamic Shadows cast by them.

NPC entities 

have the prop_dynamic shadow controls, plus a "disablereceiveshadows" To do: to prevent...?

prop_static entities 

have "disableshadows" as well as "disablevertexlighting", "disableselfshadowing" and "ignorenormals" vertex lighting controls.

Tyndall effects

Tyndall effects (http://en.wikipedia.org/wiki/Tyndall_effect) are caused by light scattering on suspended (colloid) particles in a transparent medium. Eg car headlights in fog.

• Halo (http://en.wikipedia.org/wiki/Halo_%28optical_phenomenon%29) (Glow Sprite) effects :

• env_sprite - entity used to create omni-directional glow or flare effects.
• env_lightglow - an asymmetrical glow (for areas of contrasting light).
• env_sun - adds a bright haloed spot to the Skybox to represent the position of the Sun or Moon.

• Lightbeam (http://en.wikipedia.org/wiki/Light_beam) (Volumetric Light) effects :

• Brush texture : models/effects/vol_light001
• Brush texture : models/effects/vol_light002
• Model : models/Effects/vol_light.mdl - use with prop_static.

• See also Render Modes for sprites, particularly World Space Glow.

Common values

City 17 day

Brightness 237 218 143 800

Ambience 190 201 220 100

Ravenholm night

Brightness 175 230 239 50

Ambience 43 45 57 5

Combine lamp

Brightness 147 226 240 3000

Ambience N/A

Tungsten bulb

Brightness 254 216 146

Ambience N/A

Fluorescent bulb

Brightness 159 237 215

Ambience N/A

For values to accompany the stock skybox materials, see Sky List.

Notes

• Naming a light makes it more expensive. Only name lights when you need to. Multiple lights sharing the same name are cheaper than lights with separate names.
• light_dynamic is especially expensive, and will not even show up on some systems
• The basic light entities do not come with a visible representation (e.g. a lightbulb). For that you need a prop. See HL2 light props for a list.
• The basic light entities do not come with a "glow" as you'd expect to see in a foggy or misty area. To provide this, either compile and run the map with HDR enabled, or add a point_spotlight (with dynamic lighting off unless needed) or env_lightglow entity.
• Maps will not be lit unless you run vrad (or equivalent). Vrad will not run properly and will not calculate realistic light bounces unless the level is free of leaks.
• Several textures provide their own light & can do so using lights.rad in a mod's directory or the one in sourcesdk/bin.
• Moving brushed-based objects will not change the way they are lit. Their lighting will be calculated only according to their positions in Hammer. (e.g. a brush in a dark room will not become bright if it is brought into a bright room.)

Console commands

• mat_fullbright boolean — Toggles map lighting

See also

• HL2 light props
• Color theory (level design)
• Light entities - A list of light entities.

External links

• Lighting Tutorial (http://www.freewebs.com/flashsjunk/lightingtutorial.htm) - Covers entities & variables with examples
• Quadratic/Linear/Constant in Lights (http://www.editlife.net/tutorials.php?id=15)