three.js 实现图片马赛克化与 BufferGeometry 粒子系统应用

initCanvas() {
  canvas = document.createElement('canvas');
  content = canvas.getContext('2d');
  canvas.width = 1600;
  canvas.height = 1200;
  img = new Image();
  img.crossOrigin = '*';
  img.src = "/static/images/base/girl.jpg";
  img.onload = () => {
    content.drawImage(img, 0, 0, canvas.width, canvas.height);
    imgDate = content.getImageData(0, 0, canvas.width, canvas.height);
    this.createPotCloud();  //创建点云
  };
}

createPotCloud() {
  if (points) {
    scene.remove(points)
  }
  let cw = Math.floor(canvas.width / size);
  let ch = Math.floor(canvas.height / size);
  particles = cw * ch;
  geometry = new THREE.BufferGeometry();
  positions = new Float32Array(Math.floor(particles * 3));
  positions_af = new Float32Array(Math.floor(particles * 3));
  var colors = new Float32Array(Math.floor(particles * 3));
  for (var i = 0; i < positions.length; i += 1) {

    positions[3 * i] = - canvas.width / 2 + (i % cw) * size;
    positions[3 * i + 1] = canvas.height / 2 + Math.floor((-1 - i) / cw) * size;
    positions[3 * i + 2] = 0;

    let selectPos = size * (i % cw) + Math.floor(i / cw) * cw * size * size;
    colors[3 * i] = imgDate.data[4 * selectPos] / 255.0;
    colors[3 * i + 1] = imgDate.data[4 * selectPos + 1] / 255.0;
    colors[3 * i + 2] = imgDate.data[4 * selectPos + 2] / 255.0;
  }
  geometry.setAttribute('position', new THREE.BufferAttribute(positions, 3));
  geometry.setAttribute('color', new THREE.BufferAttribute(colors, 3))
  geometry.dynamic = true;
  geometry.attributes.position.needsUpdate = true;
  var material = new THREE.PointsMaterial({ size: size, vertexColors: THREE.VertexColors })
  points = new THREE.Points(geometry, material);
  points.name = 'points';
  scene.add(points);
  loaded = true;
},