three.js通过合并几何体来优化多对象性能

性能优化的主要方法之一就是合并几何体，使用three.js开发库提供的BufferGeometryUtils.mergeBufferGeometries方法，原理很简单，就是减少渲染流程执行次数。

three, performance, optimization, merge

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JavaScript

编译

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HTML

function main() {
  const canvas = document.querySelector('#c');
  const renderer = new THREE.WebGLRenderer({canvas});

const fov = 60;
  const aspect = 2;  // the canvas default
  const near = 0.1;
  const far = 10;
  const camera = new THREE.PerspectiveCamera(fov, aspect, near, far);
  camera.position.z = 2.5;

const controls = new OrbitControls(camera, canvas);
  controls.enableDamping = true;
  controls.enablePan = false;
  controls.minDistance = 1.2;
  controls.maxDistance = 4;
  controls.update();

const scene = new THREE.Scene();
  scene.background = new THREE.Color('black');

{
    const loader = new THREE.TextureLoader();
    const texture = loader.load('https://threejsfundamentals.org/threejs/resources/images/world.jpg', render);
    const geometry = new THREE.SphereBufferGeometry(1, 64, 32);
    const material = new THREE.MeshBasicMaterial({map: texture});
    scene.add(new THREE.Mesh(geometry, material));
  }

async function loadFile(url) {
    const req = await fetch(url);
    return req.text();
  }

function addBoxes(file) {
    const {min, max, data} = file;
    const range = max - min;

// these helpers will make it easy to position the boxes
    // We can rotate the lon helper on its Y axis to the longitude
    const lonHelper = new THREE.Object3D();
    scene.add(lonHelper);
    // We rotate the latHelper on its X axis to the latitude
    const latHelper = new THREE.Object3D();
    lonHelper.add(latHelper);
    // The position helper moves the object to the edge of the sphere
    const positionHelper = new THREE.Object3D();
    positionHelper.position.z = 1;
    latHelper.add(positionHelper);
    // Used to move the center of the cube so it scales from the position Z axis
    const originHelper = new THREE.Object3D();
    originHelper.position.z = 0.5;
    positionHelper.add(originHelper);

const color = new THREE.Color();

const lonFudge = Math.PI * .5;
    const latFudge = Math.PI * -0.135;
    const geometries = [];
    data.forEach((row, latNdx) => {
      row.forEach((value, lonNdx) => {
        if (value === undefined) {
          return;
        }
        const amount = (value - min) / range;

const boxWidth = 1;
        const boxHeight = 1;
        const boxDepth = 1;
        const geometry = new THREE.BoxBufferGeometry(boxWidth, boxHeight, boxDepth);

// adjust the helpers to point to the latitude and longitude
        lonHelper.rotation.y = THREE.Math.degToRad(lonNdx + file.xllcorner) + lonFudge;
        latHelper.rotation.x = THREE.Math.degToRad(latNdx + file.yllcorner) + latFudge;

// use the world matrix of the origin helper to
        // position this geometry
        positionHelper.scale.set(0.005, 0.005, THREE.Math.lerp(0.01, 0.5, amount));
        originHelper.updateWorldMatrix(true, false);
        geometry.applyMatrix(originHelper.matrixWorld);

// compute a color
        const hue = THREE.Math.lerp(0.7, 0.3, amount);
        const saturation = 1;
        const lightness = THREE.Math.lerp(0.4, 1.0, amount);
        color.setHSL(hue, saturation, lightness);
        // get the colors as an array of values from 0 to 255
        const rgb = color.toArray().map(v => v * 255);

// make an array to store colors for each vertex
        const numVerts = geometry.getAttribute('position').count;
        const itemSize = 3;  // r, g, b
        const colors = new Uint8Array(itemSize * numVerts);

// copy the color into the colors array for each vertex
        colors.forEach((v, ndx) => {
          colors[ndx] = rgb[ndx % 3];
        });

const normalized = true;
        const colorAttrib = new THREE.BufferAttribute(colors, itemSize, normalized);
        geometry.setAttribute('color', colorAttrib);

geometries.push(geometry);
      });
    });

const mergedGeometry = BufferGeometryUtils.mergeBufferGeometries(
        geometries, false);
    const material = new THREE.MeshBasicMaterial({
      vertexColors: THREE.VertexColors,
    });
    const mesh = new THREE.Mesh(mergedGeometry, material);
    scene.add(mesh);
  }

loadFile('/uploads/1911/gpw_v4_basic_demographic_characteristics_rev10_a000_014mt_2010_cntm_1_deg.asc')
    .then(parseData)
    .then(addBoxes)
    .then(render);

function resizeRendererToDisplaySize(renderer) {
    const canvas = renderer.domElement;
    const width = canvas.clientWidth;
    const height = canvas.clientHeight;
    const needResize = canvas.width !== width || canvas.height !== height;
    if (needResize) {
      renderer.setSize(width, height, false);
    }
    return needResize;
  }

let renderRequested = false;

function render() {
    renderRequested = undefined;

if (resizeRendererToDisplaySize(renderer)) {
      const canvas = renderer.domElement;
      camera.aspect = canvas.clientWidth / canvas.clientHeight;
      camera.updateProjectionMatrix();
    }

controls.update();
    renderer.render(scene, camera);
  }
  render();

function requestRenderIfNotRequested() {
    if (!renderRequested) {
      renderRequested = true;
      requestAnimationFrame(render);
    }
  }

controls.addEventListener('change', requestRenderIfNotRequested);
  window.addEventListener('resize', requestRenderIfNotRequested);
}

main();

</script>

性能优化的主要方法之一就是合并几何体，使用three.js开发库提供的BufferGeometryUtils.mergeBufferGeometries方法，原理很简单，就是减少渲染流程执行次数。

three, performance, optimization, merge

编辑器支持Emmet

快捷键

性能优化的主要方法之一就是合并几何体，使用three.js开发库提供的BufferGeometryUtils.mergeBufferGeometries方法，原理很简单，就是减少渲染流程执行次数。

three, performance, optimization, merge

three.js通过多点控制器来交互绘制多边形物体

three.js实例化几何体（InstancedBufferGeometry）代码示例

编辑器支持Emmet

快捷键

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