Class reference

LightmapGI

Inherits VisualInstance3D

Computes and stores baked lightmaps for fast global illumination.

Description

The LightmapGI node is used to compute and store baked lightmaps. Lightmaps are used to provide high-quality indirect lighting with very little light leaking. LightmapGI can also provide rough reflections using spherical harmonics if directional is enabled. Dynamic objects can receive indirect lighting thanks to light probes, which can be automatically placed by setting generate_probes_subdiv to a value other than GENERATE_PROBES_DISABLED. Additional lightmap probes can also be added by creating LightmapProbe nodes. The downside is that lightmaps are fully static and cannot be baked in an exported project. Baking a LightmapGI node is also slower compared to VoxelGI. Procedural generation: Lightmap baking functionality is only available in the editor. This means LightmapGI is not suited to procedurally generated or user-built levels. For procedurally generated or user-built levels, use VoxelGI or SDFGI instead (see Environment.sdfgi_enabled). Performance: LightmapGI provides the best possible run-time performance for global illumination. It is suitable for low-end hardware including integrated graphics and mobile devices. Note: Due to how lightmaps work, most properties only have a visible effect once lightmaps are baked again. Note: Lightmap baking on CSGShape3Ds and PrimitiveMeshes is not supported, as these cannot store UV2 data required for baking. Note: If no custom lightmappers are installed, LightmapGI can only be baked from devices that support the Forward+ or Mobile renderers. Note: The LightmapGI node only bakes light data for child nodes of its parent. Nodes further up the hierarchy of the scene will not be baked.

Properties

`float bias = 0.0005`

The bias to use when computing shadows. Increasing bias can fix shadow acne on the resulting baked lightmap, but can introduce peter-panning (shadows not connecting to their casters). Real-time Light3D shadows are not affected by this bias property.

`float bounce_indirect_energy = 1.0`

The energy multiplier for each bounce. Higher values will make indirect lighting brighter. A value of 1.0 represents physically accurate behavior, but higher values can be used to make indirect lighting propagate more visibly when using a low number of bounces. This can be used to speed up bake times by lowering the number of bounces then increasing bounce_indirect_energy. Note: bounce_indirect_energy only has an effect if bounces is set to a value greater than or equal to 1.

`int bounces = 3`

Number of light bounces that are taken into account during baking. Higher values result in brighter, more realistic lighting, at the cost of longer bake times. If set to 0, only environment lighting, direct light and emissive lighting is baked.

`CameraAttributes camera_attributes`

The CameraAttributes resource that specifies exposure levels to bake at. Auto-exposure and non exposure properties will be ignored. Exposure settings should be used to reduce the dynamic range present when baking. If exposure is too high, the LightmapGI will have banding artifacts or may have over-exposure artifacts.

`int denoiser_range = 10`

The distance in pixels from which the denoiser samples. Lower values preserve more details, but may give blotchy results if the lightmap quality is not high enough. Only effective if use_denoiser is true and ProjectSettings.rendering/lightmapping/denoising/denoiser is set to JNLM.

`float denoiser_strength = 0.1`

The strength of denoising step applied to the generated lightmaps. Only effective if use_denoiser is true and ProjectSettings.rendering/lightmapping/denoising/denoiser is set to JNLM.

`bool directional = false`

If true, bakes lightmaps to contain directional information as spherical harmonics. This results in more realistic lighting appearance, especially with normal mapped materials and for lights that have their direct light baked (Light3D.light_bake_mode set to Light3D.BAKE_STATIC and with Light3D.editor_only set to false). The directional information is also used to provide rough reflections for static and dynamic objects. This has a small run-time performance cost as the shader has to perform more work to interpret the direction information from the lightmap. Directional lightmaps also take longer to bake and result in larger file sizes. Note: The property's name has no relationship with DirectionalLight3D. directional works with all light types.

`Color environment_custom_color = Color(1, 1, 1, 1)`

The color to use for environment lighting. Only effective if environment_mode is ENVIRONMENT_MODE_CUSTOM_COLOR.

`float environment_custom_energy = 1.0`

The color multiplier to use for environment lighting. Only effective if environment_mode is ENVIRONMENT_MODE_CUSTOM_COLOR.

`Sky environment_custom_sky`

The sky to use as a source of environment lighting. Only effective if environment_mode is ENVIRONMENT_MODE_CUSTOM_SKY.

`int environment_mode = 1`

The environment mode to use when baking lightmaps.

`int generate_probes_subdiv = 2`

The level of subdivision to use when automatically generating LightmapProbes for dynamic object lighting. Higher values result in more accurate indirect lighting on dynamic objects, at the cost of longer bake times and larger file sizes. Note: Automatically generated LightmapProbes are not visible as nodes in the Scene tree dock, and cannot be modified this way after they are generated. Note: Regardless of generate_probes_subdiv, direct lighting on dynamic objects is always applied using Light3D nodes in real-time.

`bool interior = false`

If true, ignore environment lighting when baking lightmaps.

`LightmapGIData light_data`

The LightmapGIData associated to this LightmapGI node. This resource is automatically created after baking, and is not meant to be created manually.

`int max_texture_size = 16384`

The maximum texture size for the generated texture atlas. Higher values will result in fewer slices being generated, but may not work on all hardware as a result of hardware limitations on texture sizes. Leave max_texture_size at its default value of 16384 if unsure.

`int quality = 1`

The quality preset to use when baking lightmaps. This affects bake times, but output file sizes remain mostly identical across quality levels. To further speed up bake times, decrease bounces, disable use_denoiser and/or decrease texel_scale. To further increase quality, enable supersampling and/or increase texel_scale.

`int shadowmask_mode = 0`

Experimental.

The shadowmasking policy to use for directional shadows on static objects that are baked with this LightmapGI instance. Shadowmasking allows DirectionalLight3D nodes to cast shadows even outside the range defined by their DirectionalLight3D.directional_shadow_max_distance property. This is done by baking a texture that contains a shadowmap for the directional light, then using this texture according to the current shadowmask mode. Note: The shadowmask texture is only created if shadowmask_mode is not LightmapGIData.SHADOWMASK_MODE_NONE. To see a difference, you need to bake lightmaps again after switching from LightmapGIData.SHADOWMASK_MODE_NONE to any other mode.

`bool supersampling = false`

If true, lightmaps are baked with the texel scale multiplied with supersampling_factor and downsampled before saving the lightmap (so the effective texel density is identical to having supersampling disabled). Supersampling provides increased lightmap quality with less noise, smoother shadows and better shadowing of small-scale features in objects. However, it may result in significantly increased bake times and memory usage while baking lightmaps. Padding is automatically adjusted to avoid increasing light leaking.

`float supersampling_factor = 2.0`

The factor by which the texel density is multiplied for supersampling. For best results, use an integer value. While fractional values are allowed, they can result in increased light leaking and a blurry lightmap. Higher values may result in better quality, but also increase bake times and memory usage while baking. See supersampling for more information.

`float texel_scale = 1.0`

Scales the lightmap texel density of all meshes for the current bake. This is a multiplier that builds upon the existing lightmap texel size defined in each imported 3D scene, along with the per-mesh density multiplier (which is designed to be used when the same mesh is used at different scales). Lower values will result in faster bake times. For example, doubling texel_scale doubles the lightmap texture resolution for all objects on each axis, so it will quadruple the texel count.

`bool use_denoiser = true`

If true, uses a GPU-based denoising algorithm on the generated lightmap. This eliminates most noise within the generated lightmap at the cost of longer bake times. File sizes are generally not impacted significantly by the use of a denoiser, although lossless compression may do a better job at compressing a denoised image.

`bool use_texture_for_bounces = true`

If true, a texture with the lighting information will be generated to speed up the generation of indirect lighting at the cost of some accuracy. The geometry might exhibit extra light leak artifacts when using low resolution lightmaps or UVs that stretch the lightmap significantly across surfaces. Leave use_texture_for_bounces at its default value of true if unsure. Note: use_texture_for_bounces only has an effect if bounces is set to a value greater than or equal to 1.

Methods

`ENVIRONMENT_MODE_CUSTOM_SKY = 2`

Enum: EnvironmentMode

Use environment_custom_sky as a source of environment lighting when baking lightmaps.

`ENVIRONMENT_MODE_CUSTOM_COLOR = 3`

Enum: EnvironmentMode

Use environment_custom_color multiplied by environment_custom_energy as a constant source of environment lighting when baking lightmaps.

Tutorials

Using Lightmap global illumination

Source revision 5592dc3a7a61