Lightmap

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Doom level format
Things Linedefs Sidedefs Vertices Segs Subsectors Nodes Sectors Reject Blockmap
Extensions: ACS Behavior Leafs Lights Macros Floors
Source port extensions: Extended nodes FraggleScript ExtraData Dialogue Lightmap

Strife: Veteran Edition's MAP03, containing both GL-format nodes and DLight lightmaps.

Lightmaps are structures that contain information about world lighting, relative to existing level geometry. Lightmaps require a dedicated compilation tool, the process of compiling such data is often referred to as "baking". The Quake renderer was the earliest instance of a video game using baked-in lightmaps. Some advanced, hardware-accelerated Doom engine ports have added support for bespoke lightmap formats.

Formats

Two notable lightmap formats exist for Doom engine ports.

DLight

Main article: DLight

Created by Kaiser for Doom64 EX and also used for Strife: Veteran Edition, the DLight format offers an additional set of "LM_"-prefixed lumps, similar to the community-made hardware rendering GL nodes format, which will also get appended to the end of the map's lumps. DLight provides a separate config configuration file, in order to correctly set up lighting data for baking. This makes the format suitable for adding to binary-based map formats, which otherwise do not have the structures needed for adding new data about the map.

ZDRay

Main article: ZDRay

The ZDRay format uses a single LIGHTMAP lump and only works with the zdoom UDMF namespace. It requires the level editor and mapper to define the properties in the map data itself, in contrast to DLight's separate config file approach.

Lightmaps format support across builders

	DLight (LM)	ZDRay (LIGHTMAP)
DLight	Yes	No
ZDRay	No	Yes

Lightmaps format support across ports

	DLight (LM)	ZDRay (LIGHTMAP)	Notes
Strife: Veteran Edition	Yes	No
GZDoom	No	Yes	Experimental. Requires the -enablelightmaps CLI parameter.
UZDoom	No	Yes	Experimental. Requires the -enablelightmaps CLI parameter.
VKDoom	No	Yes	VKDoom also supports compiling lightmaps internally, if required to do so.