Iridescence

Thin-film interference produces view-dependent colors, useful for coated glass, soap films, and decorative finishes.

The CompareIridescence sample demonstrates this capability. Drag to orbit and scroll to zoom.

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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
iridescenceFactor	number	0	Strength of the thin-film response, in the range 0–1.
iridescenceIor	number	1.3	Index of refraction of the thin film.
iridescenceThicknessRange	Readonly<Vector2 | NumberArray2>	[100, 400]	Minimum and maximum film thickness in nanometers.
iridescenceMapEnabled	boolean	false	Enables iridescence-strength texture sampling.

PBRMaterialBindings

Texture resources are supplied separately through PBRMaterialBindings. Each field below is optional and accepts Texture | null. createPBRMaterial() derives map-enabled flags from these resources. Enable the corresponding Model shader define listed below when supplying a texture; the helper does not choose the model shader defines.

Field	Model define	Description
pbr_iridescenceSampler	HAS_IRIDESCENCEMAP: true	Texture resource for the iridescence slot.
pbr_iridescenceThicknessSampler	HAS_IRIDESCENCETHICKNESSMAP: true	Texture resource for the iridescenceThickness slot.

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: {
    iridescenceFactor: 1,
    iridescenceIor: 1.3,
    iridescenceThicknessRange: [100, 400]
  }
});

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

The stock shader uses a view-dependent thin-film approximation rather than a complete spectral simulation.

glTF support

KHR_materials_iridescence supplies film factors and optional intensity and thickness maps.

See glTF materials and textures, glTF animation, and the extension support matrix for adapter details and current support limits.

All engine features