Volume Scattering

Volume scattering approximates light redirected inside a material using local thickness and a directional phase response.

Example

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Configure the material

The following fields update an existing PBR material; see Materials guide.

material.setProps({
  pbrMaterial: {
    metallicRoughnessValues: [0, 0.4],
    thicknessFactor: 0.6,
    attenuationDistance: 0.6,
    diffuseTransmissionFactor: 0.7,
    multiscatterColorFactor: [0.9, 0.35, 0.18],
    scatterAnisotropy: 0.25
  }
});

Parameters and textures

This capability is experimental. multiscatterColorFactor supplies scattering color and its texture uses sRGB RGB. scatterAnisotropy ranges from -1 to 1 and controls the Henyey–Greenstein phase response. The implementation is a local thickness-aware approximation; it does not perform spatial diffusion, a subsurface random walk, or multiple-surface transport. The glTF volume-scatter mapping follows an unratified draft.

attenuationDistance controls the optical distance over which scattering becomes significant, using the same units as thickness. Set it to a value comparable to thicknessFactor: the example uses 0.6 for both, giving a scattering probability of approximately 0.63 from 1 - exp(-thickness / attenuationDistance). The default distance of 1e9 makes volume scattering effectively invisible at this thickness. Increasing the distance weakens scattering for a fixed thickness; decreasing it strengthens scattering.

Model integration

Enable USE_MATERIAL_EXTENSIONS: true in the compatible model's defines. Uniform updates do not add shader features or texture resources. The glTF converter supplies the matching defines and bindings when importing these material inputs.

See Textures and UV coordinates for binding names, map enablement, and color handling.

Example​