three.js 将图片马赛克化的示例代码

这篇郭先生来说说BufferGeometry，类型化数组和粒子系统的使用，并且让图片有马赛克效果（同理可以让不清晰的图片清晰化），如图所示

1. 解析图片

解析图片和上一篇一样

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
  };
}

2. 操作像素点

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;
},

可以不用纠结代码，核心思想其实我们只需要每隔一定的颜色点取出一个颜色点，然后将这个颜色赋予到geometry的color属性上，就可以了，也可以每隔两行、两列取一个点，但是图片上面的点是一维的，所以需要一些数学方法，

如图所示，原理很简单哦。将不清晰的图片清晰化，就是需要插入更多的像素点，插入的像素点，需要根据已存在的像素点的颜色进行插值，比如原图的像素点1为0xffffff，像素点2的颜色为0xdddddd，则插在两个像素点之间像素点的颜色为0xeeeeee，以此类推。

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