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InstancedUniformsMesh

This package provides a InstancedUniformsMesh class which extends Three.js's InstancedMesh to allow its material's shader uniforms to be set individually per instance. It behaves just like InstancedMesh but exposes a new method:

mesh.setUniformAt(uniformName, instanceIndex, value)

When you call setUniformAt, the geometry and the material's shaders will be automatically upgraded behind the scenes to turn that uniform into an instanced buffer attribute, filling in the other indices with the uniform's default value. You can do this for any uniform of type float, vec2, vec3, or vec4. It works both for built-in Three.js materials and also for any custom ShaderMaterial.

For example, here is how you could set random emissive and metalness values for each instance using a MeshStandardMaterial:

import { InstancedUniformsMesh } from 'three-instanced-uniforms-mesh'

const count = 100
const mesh = new InstancedUniformsMesh(
  someGeometry,
  new MeshStandardMaterial(),
  count
)
const color = new Color()
for (let i = 0; i < count; i++) {
  mesh.setMatrixAt(i, someMatrixValue)
  mesh.setUniformAt('metalness', i, Math.random())
  mesh.setUniformAt('emissive', i, color.set(Math.random() * 0xffffff))
}

While this is obviously useful for Three.js's built in materials, it really shines with custom shaders. Just declare any configurable parameters as uniforms in your custom shader, and then you can use that either on a single non-instanced Mesh by setting the material's uniforms directly, or instance it using InstancedUniformsMesh by calling setUniformAt. Your shader doesn't need to change at all to support the instancing!

Note: Calling setUniformAt automatically marks the underlying buffer attributes for upload, so unlike setMatrixAt or setColorAt you don't need to set needsUpdate manually.

Value Types

The type of the value argument should match the type of the uniform defined in the material's shader:

For a uniform of type: Pass a value of this type:
float Number
vec2 THREE.Vector2
vec3 THREE.Vector3 or THREE.Color
vec4 THREE.Vector4
mat3 (ThreeJS r132+ only) THREE.Matrix3
mat4 (ThreeJS r132+ only) THREE.Matrix4

Resetting to defaults

If you have set instance-specific values for a given uniform but you want to revert all those to the single original uniform value, you can call:

mesh.unsetUniform(uniformName)

Examples

Last update: 2024-04-09