Volume absorption

Volume thickness and absorption tint transmitted light according to the distance it travels through a material.

CompareVolume contrasts thin transmission with volume; DragonAttenuation supplies colored absorbing volumes. Select Sample model to compare the supplied examples. Drag to orbit and scroll to zoom.

Sample model

GitHub

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The embedded scenegraph viewer approximates transmission with alpha; it loads these authored volume materials but does not reproduce full scene-color refraction. Use the renderer path described below to assess physical volume appearance.

PBRMaterial reference

PBRMaterial from @luma.gl/experimental is a typed engine Material backed by the shared pbrMaterial shader module. Its material fields are defined by PBRMaterialUniforms from @luma.gl/shadertools. Pass them through createPBRMaterial(device, {uniforms}) or update them with material.setProps({pbrMaterial: {...}}).

The fields below are optional. Defaults are the shared shader defaults; imported assets can supply other values.

Field	Type	Default	Description
`transmissionFactor`	`number`	`0`	Fraction of light transmitted through the surface.
`thicknessFactor`	`number`	`0`	Volume thickness in model-space units; 0 describes a thin surface.
`attenuationColor`	`Readonly<Vector3 \| NumberArray3>`	`[1, 1, 1]`	Color transmitted after the attenuation distance.
`attenuationDistance`	`number`	`1e9`	Distance associated with attenuationColor; the large default approximates no absorption.

PBRMaterialBindings

Texture bindings accept Texture | null. createPBRMaterial() derives the map-enabled flag; the model still needs the corresponding shader define.

Binding	Model define	Description
`pbr_thicknessSampler`	`HAS_THICKNESSMAP: true`	Linear green-channel multiplier for thicknessFactor.

Supporting APIs

createPBRMaterial

createPBRMaterial(device, {uniforms, bindings, factory}) from @luma.gl/experimental returns a PBRMaterial. uniforms sets the fields listed above, bindings supplies material textures, and the optional factory shares a compatible binding schema across materials. The helper derives map-enabled flags from the supplied bindings; explicit uniform values take precedence.

MaterialFactory

createPBRMaterialFactory(device) from @luma.gl/experimental creates a reusable engine MaterialFactory configured with the pbrMaterial shader module. Pass this factory to createPBRMaterial() when creating several compatible materials.

Material

Material from @luma.gl/engine owns material uniforms and texture resources. setProps({pbrMaterial: {...}}) updates uniform values. Pass the material to a compatible Model through its material prop; models sharing it observe the same updates. Use clone({bindings: {...}}) when an appearance needs separate texture resources. Adding a texture or changing a shader feature may require matching defines and a compatible model shader layout.

See the materials guide and pbrMaterial reference.

The extended PBR shader path is disabled by default. Set USE_MATERIAL_EXTENSIONS: true in the Model construction defines to enable this feature; uniform values alone do not enable it. The glTF material parser supplies this define for imported extension materials.

Usage

import {Model} from '@luma.gl/engine';
import {createPBRMaterial, type PBRMaterial} from '@luma.gl/experimental';

// device is an initialized Device.
const material: PBRMaterial = createPBRMaterial(device, {
  uniforms: {
    metallicRoughnessValues: [0, 0.05],
    transmissionFactor: 1,
    thicknessFactor: 0.5,
    attenuationColor: [0.8, 0.95, 1],
    attenuationDistance: 2
  }
});

// modelProps contains your shaders, geometry, and buffer layout.
const model = new Model(device, {
  ...modelProps,
  material,
  defines: {...modelProps.defines, USE_MATERIAL_EXTENSIONS: true}
});

Use the shared experimental SceneRenderer or ANARI capture path when the material needs scene-color refraction. See transmission for the rendering-path requirements.

glTF support

KHR_materials_volume supplies thickness, attenuation color, attenuation distance, and an optional thickness texture (green channel). It complements KHR_materials_transmission. The adapter converts glTF’s infinite attenuation-distance default into the shader’s large finite default.

See glTF materials and textures and the extension support matrix for import details.

All engine features