three-stdlib/helpers/LightProbeHelper.js

stand-alone library of threejs examples

import { Mesh, ShaderMaterial, SphereGeometry } from "three";
class LightProbeHelper extends Mesh {
  constructor(lightProbe, size) {
    const material = new ShaderMaterial({
      type: "LightProbeHelperMaterial",
      uniforms: {
        sh: { value: lightProbe.sh.coefficients },
        // by reference
        intensity: { value: lightProbe.intensity }
      },
      vertexShader: [
        "varying vec3 vNormal;",
        "void main() {",
        "	vNormal = normalize( normalMatrix * normal );",
        "	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );",
        "}"
      ].join("\n"),
      fragmentShader: [
        "#define RECIPROCAL_PI 0.318309886",
        "vec3 inverseTransformDirection( in vec3 normal, in mat4 matrix ) {",
        "	// matrix is assumed to be orthogonal",
        "	return normalize( ( vec4( normal, 0.0 ) * matrix ).xyz );",
        "}",
        "// source: https://graphics.stanford.edu/papers/envmap/envmap.pdf",
        "vec3 shGetIrradianceAt( in vec3 normal, in vec3 shCoefficients[ 9 ] ) {",
        "	// normal is assumed to have unit length",
        "	float x = normal.x, y = normal.y, z = normal.z;",
        "	// band 0",
        "	vec3 result = shCoefficients[ 0 ] * 0.886227;",
        "	// band 1",
        "	result += shCoefficients[ 1 ] * 2.0 * 0.511664 * y;",
        "	result += shCoefficients[ 2 ] * 2.0 * 0.511664 * z;",
        "	result += shCoefficients[ 3 ] * 2.0 * 0.511664 * x;",
        "	// band 2",
        "	result += shCoefficients[ 4 ] * 2.0 * 0.429043 * x * y;",
        "	result += shCoefficients[ 5 ] * 2.0 * 0.429043 * y * z;",
        "	result += shCoefficients[ 6 ] * ( 0.743125 * z * z - 0.247708 );",
        "	result += shCoefficients[ 7 ] * 2.0 * 0.429043 * x * z;",
        "	result += shCoefficients[ 8 ] * 0.429043 * ( x * x - y * y );",
        "	return result;",
        "}",
        "uniform vec3 sh[ 9 ]; // sh coefficients",
        "uniform float intensity; // light probe intensity",
        "varying vec3 vNormal;",
        "void main() {",
        "	vec3 normal = normalize( vNormal );",
        "	vec3 worldNormal = inverseTransformDirection( normal, viewMatrix );",
        "	vec3 irradiance = shGetIrradianceAt( worldNormal, sh );",
        "	vec3 outgoingLight = RECIPROCAL_PI * irradiance * intensity;",
        "	gl_FragColor = linearToOutputTexel( vec4( outgoingLight, 1.0 ) );",
        "}"
      ].join("\n")
    });
    const geometry = new SphereGeometry(1, 32, 16);
    super(geometry, material);
    this.lightProbe = lightProbe;
    this.size = size;
    this.type = "LightProbeHelper";
    this.onBeforeRender();
  }
  dispose() {
    this.geometry.dispose();
    this.material.dispose();
  }
  onBeforeRender() {
    this.position.copy(this.lightProbe.position);
    this.scale.set(1, 1, 1).multiplyScalar(this.size);
    this.material.uniforms.intensity.value = this.lightProbe.intensity;
  }
}
export {
  LightProbeHelper
};
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