- Qt 6.8
- Qt Quick 3D
- QML Types
- Lightmapper
- Qt Quick 3D | Commercial or GPLv3

# Lightmapper QML Type

Specifies lightmap baking settings for a scene. More...

Import Statement: | `import QtQuick3D`
Since: | Qt 6.4
Inherits: | QtObject

- List of all members, including inherited members

## Properties

- adaptiveBiasEnabled : bool
- bias : float
- bounces : int
- indirectLightEnabled : bool
- indirectLightFactor : float
- indirectLightWorkgroupSize : int
- opacityThreshold : float
- samples : int

## Detailed Description

Used when baking direct and indirect lighting. These settings are not relevant at other times, such as when using already generated lightmaps to render a scene.

Note: As of Qt 6.4, lightmap baking is in an early technical preview state. Changes to features, quality, and API are likely to happen in future releases.

The Lightmapper object works in combination with:

- Model::bakedLightmap and the associated BakedLightmap,
- Model::usedInBakedLighting and Model::lightmapBaseResolution,
- Light::bakeMode,
- the engine's built-in lightmap baker.

See also Lightmaps and Global Illumination and Qt Quick 3D - Baked Lightmap Example.

## Property Documentation

adaptiveBiasEnabled : bool

Enables applying an additional, dynamic bias based on the surface normal.

The default value is true.

bias : float

Raycasting bias used during baking. Adapt the value in case artifacts occur, for example in order to reduce undesired shadowing patterns. In many cases the default value is sufficient.

The default value is 0.005.

bounces : int

The maximum number of indirect light bounces per sample. The value should at least be 1, no point in indirect light calculation otherwise.

The default value is 3.

The value heavily affects both the performance and quality of the resulting lightmaps during lightmap baking.

indirectLightEnabled : bool

Normally there is no need to change this value. The default value is true. Setting this property to false disables indirect light computation during lightmap baking. Thus the resulting texture maps will only contain direct light information. At run time, the engine will continue to use the maps normally, assuming they contain both direct and indirect lighting.

indirectLightFactor : float

Multiplier for the indirect light amount. While it is the value of 1 (i.e., not affecting the indirect light amount calculation) that provides the strictly correct rendering results, a slightly higher value can often give better looking results when using the lightmap, even with a lower number of bounces.

The default value is 1.

indirectLightWorkgroupSize : int

The size of the sample workgroups. These workgroups are attempted to be executed in parallel. (the exact behavior depends on the number of CPU cores and the QThreadPool configuration)

The default value is 32. With the default sample count of 256 this means attempting to run 8 groups in parallel per model.

opacityThreshold : float

The opacity (alpha) threshold below which an object is ignored in ray - mesh intersections when calculating lighting via raytracing. When the opacity falls below the threshold, the model (submesh) will not occlude lights and thus will not generate shadows either.

The default value is 0.5.

Note: The lightmapper takes the material's opacity and the baseColor alpha combined with the base color map's alpha into account. Other sources of semi-transparency, such as the opacity map or alpha cut-off settings are ignored during the lightmap baking process.

samples : int

The number of samples per lightmap texel.

The default value is 256.

The value heavily affects both the performance and quality of the resulting lightmaps during lightmap baking.