bytev-charts/lib/plugin/three.js/examples/js/lights/LightProbeGenerator.js

基于echarts和JavaScript及ES6封装的一个可以直接调用的图表组件库，内置主题设计，简单快捷，且支持用户自定义配置； npm 安装方式: npm install bytev-charts 若启动提示还需额外install插件,则运行 npm install @babel/runtime-corejs2 即可;

import "core-js/modules/es.array.iterator.js";
import "core-js/modules/es.array-buffer.slice.js";
import "core-js/modules/es.object.to-string.js";
import "core-js/modules/es.typed-array.uint8-array.js";
import "core-js/modules/es.typed-array.copy-within.js";
import "core-js/modules/es.typed-array.every.js";
import "core-js/modules/es.typed-array.fill.js";
import "core-js/modules/es.typed-array.filter.js";
import "core-js/modules/es.typed-array.find.js";
import "core-js/modules/es.typed-array.find-index.js";
import "core-js/modules/es.typed-array.for-each.js";
import "core-js/modules/es.typed-array.includes.js";
import "core-js/modules/es.typed-array.index-of.js";
import "core-js/modules/es.typed-array.iterator.js";
import "core-js/modules/es.typed-array.join.js";
import "core-js/modules/es.typed-array.last-index-of.js";
import "core-js/modules/es.typed-array.map.js";
import "core-js/modules/es.typed-array.reduce.js";
import "core-js/modules/es.typed-array.reduce-right.js";
import "core-js/modules/es.typed-array.reverse.js";
import "core-js/modules/es.typed-array.set.js";
import "core-js/modules/es.typed-array.slice.js";
import "core-js/modules/es.typed-array.some.js";
import "core-js/modules/es.typed-array.sort.js";
import "core-js/modules/es.typed-array.subarray.js";
import "core-js/modules/es.typed-array.to-locale-string.js";
import "core-js/modules/es.typed-array.to-string.js";
console.warn("THREE.LightProbeGenerator: As part of the transition to ES6 Modules, the files in 'examples/js' were deprecated in May 2020 (r117) and will be deleted in December 2020 (r124). You can find more information about developing using ES6 Modules in https://threejs.org/docs/#manual/en/introduction/Installation.");
THREE.LightProbeGenerator = {
  // https://www.ppsloan.org/publications/StupidSH36.pdf
  fromCubeTexture: function fromCubeTexture(cubeTexture) {
    var norm,
        lengthSq,
        weight,
        totalWeight = 0;
    var coord = new THREE.Vector3();
    var dir = new THREE.Vector3();
    var color = new THREE.Color();
    var shBasis = [0, 0, 0, 0, 0, 0, 0, 0, 0];
    var sh = new THREE.SphericalHarmonics3();
    var shCoefficients = sh.coefficients;

    for (var faceIndex = 0; faceIndex < 6; faceIndex++) {
      var image = cubeTexture.image[faceIndex];
      var width = image.width;
      var height = image.height;
      var canvas = document.createElement('canvas');
      canvas.width = width;
      canvas.height = height;
      var context = canvas.getContext('2d');
      context.drawImage(image, 0, 0, width, height);
      var imageData = context.getImageData(0, 0, width, height);
      var data = imageData.data;
      var imageWidth = imageData.width; // assumed to be square

      var pixelSize = 2 / imageWidth;

      for (var i = 0, il = data.length; i < il; i += 4) {
        // RGBA assumed
        // pixel color
        color.setRGB(data[i] / 255, data[i + 1] / 255, data[i + 2] / 255); // convert to linear color space

        convertColorToLinear(color, cubeTexture.encoding); // pixel coordinate on unit cube

        var pixelIndex = i / 4;
        var col = -1 + (pixelIndex % imageWidth + 0.5) * pixelSize;
        var row = 1 - (Math.floor(pixelIndex / imageWidth) + 0.5) * pixelSize;

        switch (faceIndex) {
          case 0:
            coord.set(-1, row, -col);
            break;

          case 1:
            coord.set(1, row, col);
            break;

          case 2:
            coord.set(-col, 1, -row);
            break;

          case 3:
            coord.set(-col, -1, row);
            break;

          case 4:
            coord.set(-col, row, 1);
            break;

          case 5:
            coord.set(col, row, -1);
            break;
        } // weight assigned to this pixel


        lengthSq = coord.lengthSq();
        weight = 4 / (Math.sqrt(lengthSq) * lengthSq);
        totalWeight += weight; // direction vector to this pixel

        dir.copy(coord).normalize(); // evaluate SH basis functions in direction dir

        THREE.SphericalHarmonics3.getBasisAt(dir, shBasis); // accummuulate

        for (var j = 0; j < 9; j++) {
          shCoefficients[j].x += shBasis[j] * color.r * weight;
          shCoefficients[j].y += shBasis[j] * color.g * weight;
          shCoefficients[j].z += shBasis[j] * color.b * weight;
        }
      }
    } // normalize


    norm = 4 * Math.PI / totalWeight;

    for (var j = 0; j < 9; j++) {
      shCoefficients[j].x *= norm;
      shCoefficients[j].y *= norm;
      shCoefficients[j].z *= norm;
    }

    return new THREE.LightProbe(sh);
  },
  fromCubeRenderTarget: function fromCubeRenderTarget(renderer, cubeRenderTarget) {
    // The renderTarget must be set to RGBA in order to make readRenderTargetPixels works
    var norm,
        lengthSq,
        weight,
        totalWeight = 0;
    var coord = new THREE.Vector3();
    var dir = new THREE.Vector3();
    var color = new THREE.Color();
    var shBasis = [0, 0, 0, 0, 0, 0, 0, 0, 0];
    var sh = new THREE.SphericalHarmonics3();
    var shCoefficients = sh.coefficients;

    for (var faceIndex = 0; faceIndex < 6; faceIndex++) {
      var imageWidth = cubeRenderTarget.width; // assumed to be square

      var data = new Uint8Array(imageWidth * imageWidth * 4);
      renderer.readRenderTargetPixels(cubeRenderTarget, 0, 0, imageWidth, imageWidth, data, faceIndex);
      var pixelSize = 2 / imageWidth;

      for (var i = 0, il = data.length; i < il; i += 4) {
        // RGBA assumed
        // pixel color
        color.setRGB(data[i] / 255, data[i + 1] / 255, data[i + 2] / 255); // convert to linear color space

        convertColorToLinear(color, cubeRenderTarget.texture.encoding); // pixel coordinate on unit cube

        var pixelIndex = i / 4;
        var col = -1 + (pixelIndex % imageWidth + 0.5) * pixelSize;
        var row = 1 - (Math.floor(pixelIndex / imageWidth) + 0.5) * pixelSize;

        switch (faceIndex) {
          case 0:
            coord.set(1, row, -col);
            break;

          case 1:
            coord.set(-1, row, col);
            break;

          case 2:
            coord.set(col, 1, -row);
            break;

          case 3:
            coord.set(col, -1, row);
            break;

          case 4:
            coord.set(col, row, 1);
            break;

          case 5:
            coord.set(-col, row, -1);
            break;
        } // weight assigned to this pixel


        lengthSq = coord.lengthSq();
        weight = 4 / (Math.sqrt(lengthSq) * lengthSq);
        totalWeight += weight; // direction vector to this pixel

        dir.copy(coord).normalize(); // evaluate SH basis functions in direction dir

        THREE.SphericalHarmonics3.getBasisAt(dir, shBasis); // accummuulate

        for (var j = 0; j < 9; j++) {
          shCoefficients[j].x += shBasis[j] * color.r * weight;
          shCoefficients[j].y += shBasis[j] * color.g * weight;
          shCoefficients[j].z += shBasis[j] * color.b * weight;
        }
      }
    } // normalize


    norm = 4 * Math.PI / totalWeight;

    for (var j = 0; j < 9; j++) {
      shCoefficients[j].x *= norm;
      shCoefficients[j].y *= norm;
      shCoefficients[j].z *= norm;
    }

    return new THREE.LightProbe(sh);
  }
};

var convertColorToLinear = function convertColorToLinear(color, encoding) {
  switch (encoding) {
    case THREE.sRGBEncoding:
      color.convertSRGBToLinear();
      break;

    case THREE.LinearEncoding:
      break;

    default:
      console.warn('WARNING: LightProbeGenerator convertColorToLinear() encountered an unsupported encoding.');
      break;
  }

  return color;
};