Baked lighting in Godot¶

When you bake a map in the editor, the light map is saved inside the .tdm. Godot does not bake anything itself, each build just turns the stored bake into Godot's own lightmap node.

What the build adds¶

Part	What it gets
A `LightmapGI` named `baked_lighting`	A child of the `FuncGodotMap`, holding the light map, the sun shadow mask and the light probes
Baked meshes	Their light map coordinates as UV2 and a static GI mode, streamed chunks included
Lights and the sun	Godot's bake mode from their `bake_mode` or `sun_bake_mode`, see Light keys

With the sun on bounce, the sun stays real time and the baked shadow mask shades what lies past its shadow distance.

Faces you changed after the bake fall back to the map's average light, so they look plausible but flat until you bake again.

Light probes¶

Moving objects, like the player, props and doors, take their light from the light probes around them, so they pick up the baked bounce light and blend in.

The bake places probes on a 2 meter grid over the box around the baked geometry and drops the ones inside solids. Where the grid is too coarse, like a narrow corridor or a stair, add a light_probe entity for one more. A map gets about 1000 probes at most, hand placed ones included, so on a bigger map the grid spreads out.

Probe entities¶

Entity	Kind	Godot node	Use it for
`light_probe`	Point	`LightmapProbe`	An extra light probe for the bake, see above
`env_reflection_probe`	Brush volume	`ReflectionProbe` sized to the brush	Reflections that match a room on glossy floors and metal
`env_voxel_gi`	Brush volume	`VoxelGI` sized to the brush	Real time bounce light that follows moving lights and objects

You find all three in the Entities tab. Drag light_probe into a view. For the two volumes, draw a box around the room, then right click the card and pick Turn selected brushes into it.

The Entities tab filtered to env_, with the env_voxel_gi card right clicked and Turn selected brushes into it highlighted

The brush only gives the box, the build removes it. The keys of all three are listed in Props, lights and effects.

An env_voxel_gi is baked in the Godot editor every time the map builds. On a big volume, set bake_on_build to 0 and bake it by hand with the Bake button of the VoxelGI node instead. Maps built while the game runs skip that bake.

Using another lightmapper¶

Want to bake with Godot's own LightmapGI instead? Untick Use Baked Lighting on the FuncGodotMap to leave the stored bake out. The build then adds no baked_lighting node and leaves the lights' bake modes alone. Tick Unwrap UV2 in Build Flags so the meshes get the UV2 a Godot bake needs.