javascript - 如何平移 THREE.PointCloud 对象中的顶点？

Question

我正在尝试:

• 绘制一个 THREE.PointCloud 对象，大约。 150k 点，其中点从网络应用程序发送。
• 缩放 THREE.PointCloud 对象中的点以获得类似于此的结果(使用 MayaVi 渲染):

问题在于:

• 传递给 THREE.PointCloud 对象的数据似乎不准确
• 在 three.js 中呈现时，点被排列成八个立方体，原因不明(我没有对点应用任何缩放或转换)

---

示例服务器响应(我在本文底部包含示例数据):

{'geometry': [[-156, 65, 89],
              [268, 84, 337],
              [-205, 68, 170],
              [-87, 69, 52],
              ...
              [289, 81, 143],
              [141, 78, 280],
              [403, 75, 351]],
 'metadata': {'max': {'x': 421, 'y': 105, 'z': 458},
          'min': {'x': -335, 'y': 63, 'z': 39}}}

---

用于创建点云的three.js代码:

  var container;
  var scene, camera, renderer, controls;
  var geometry, material, mesh;

  init();
  animate();

  function init() {
    scene = new THREE.Scene();
    camera = new THREE.PerspectiveCamera(27, window.innerWidth / window.innerHeight, 5, 5000);
    camera.position.z = 2750;

    //Add a buffer geometry for particle system
    var geometry = new THREE.BufferGeometry();
    var particles = {{ len(topology['geometry']) }};
    var geometry = new THREE.BufferGeometry();
    var positions = new Float32Array(particles * 3);
    var colors = new Float32Array(particles * 3);
    var color = new THREE.Color();

    var i = 0;
    {% for point in topology['geometry'] %}
      var x = {{ point[0] }};
      var y = {{ point[1] }};
      var z = {{ point[2] }};

      //Store the position of the point
      positions[i]     = x;
      positions[i + 1] = y;
      positions[i + 2] = z;

      //Assign a colour to the point
      color.setRGB(0.42, 0.42, 0.42);
      colors[i]     = color.r;
      colors[i + 1] = color.g;
      colors[i + 2] = color.b;
      i+=1;
    {% end %}

    geometry.addAttribute('position', new THREE.BufferAttribute(positions, 3));
    geometry.addAttribute('color', new THREE.BufferAttribute(colors, 3));
    geometry.computeBoundingSphere();

    var material = new THREE.PointCloudMaterial({ size: 15, vertexColors: THREE.VertexColors });
    particleSystem = new THREE.PointCloud(geometry, material);
    scene.add(particleSystem);

    //Lights
    light = new THREE.DirectionalLight(0xffffff);
    light.position.set(1, 1, 1);
    scene.add(light);

    //Set up renderer
    renderer = new THREE.WebGLRenderer({ antialias:false });
    renderer.setSize(window.innerWidth, window.innerHeight);
    renderer.setPixelRatio(window.devicePixelRatio);

    //Attach renderer to #container DOM element
    container = document.getElementById('container');
    container.appendChild(renderer.domElement);

    //Add window listener for resize events
    window.addEventListener('resize', onWindowResize, false);

    //Call render loop
    animate();
  }

  function onWindowResize(){
    camera.aspect = window.innerWidth / window.innerHeight;
    camera.updateProjectionMatrix();
    renderer.setSize(window.innerWidth, window.innerHeight);
    render();
  }

  function animate() {
    requestAnimationFrame(animate);
    renderer.render(scene, camera);
  }

  function render(){
    renderer.render(scene, camera);
  }

场景最终看起来是这样的:

有什么建议吗？我使用了以下示例代码，但我很难正确实现数据集中点的缩放:http://threejs.org/examples/#webgl_buffergeometry_particles

链接到我正在使用的数据样本(2MB，180k 行):https://gist.githubusercontent.com/TylerJFisher/659e3e233f8aa458feee/raw/889c0dd0093fd0476094af48488aab62c8666271/topology.asc

Answer 1

我使用了您的样本数据。把它放在一个数组中，像这样:

var data = [
"-156 65 89",
"268 84 337",
"-205 68 170",
"-87 69 52",
...
];

并为 PointCloud 使用了 THREE.Geometry():

            var geometry = new THREE.Geometry();
            var colors = [];

            for ( var x = 0; x < data.length; x++){
                    var pointCoord = data[ x ].split(" ");
                    if ( pointCoord.length != 3 ) continue;
                    var currentColor = new THREE.Color( 0.5, 1, 0.5 );
                    colors.push( currentColor );
                    geometry.vertices.push(
                        new THREE.Vector3(
                            pointCoord[2],
                            pointCoord[1],
                            pointCoord[0]
                        )
                    );
                };
            //

            console.log( geometry.vertices.length );

            geometry.colors = colors;

            var material = new THREE.PointCloudMaterial( { size: 1, vertexColors: THREE.VertexColors } );

            particleSystem = new THREE.PointCloud( geometry, material );
            scene.add( particleSystem );

此外，在地理数据中，坐标 x 和 y 总是交换(在本例中，有 x 和 z)。如果您不这样做，那么您将获得镜像对象。这就是为什么我把它写成

                        new THREE.Vector3(
                            pointCoord[2],
                            pointCoord[1],
                            pointCoord[0]
                        )

代替

                        new THREE.Vector3(
                            pointCoord[0],
                            pointCoord[1],
                            pointCoord[2]
                        )

结果在这里:geodata

是的，您的示例数据中的某些行似乎不正确。表示它们有 1 个或 2 个值，而不是 3 个。