Custom BufferGeometry - Dynamic，HTML代码在线实时编辑、实时预览

index.html

style.css

index.js

index.html

            
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            <!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <link rel="stylesheet" href="./style.css">
  <script src="./index.js"></script>
</head>

<body>
  <canvas id="c" data-engine="three.js r174"></canvas>
  <script type="importmap">{
    "imports": {
        "three": "https://cdnjs.cloudflare.com/ajax/libs/three.js/0.174.0/three.module.min.js"
    }
}</script>
</body>

</html>

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style.css

            
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html, body {
  height: 100%;
  margin: 0;
}
#c {
  width: 100%;
  height: 100%;
  display: block;
}

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index.js

            
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// Three.js - Custom BufferGeometry - Dynamic
// from https://threejs.org/manual/examples/custom-buffergeometry-dynamic.html


import * as THREE from 'three';

function main() {

    const canvas = document.querySelector( '#c' );
    const renderer = new THREE.WebGLRenderer( { antialias: true, canvas } );

    const fov = 75;
    const aspect = 2; // the canvas default
    const near = 0.1;
    const far = 100;
    const camera = new THREE.PerspectiveCamera( fov, aspect, near, far );
    camera.position.z = 3;

    const scene = new THREE.Scene();

    function addLight( ...pos ) {

        const color = 0xFFFFFF;
        const intensity = 3;
        const light = new THREE.DirectionalLight( color, intensity );
        light.position.set( ...pos );
        scene.add( light );

    }

    addLight( - 1, 2, 4 );
    addLight( 2, - 2, 3 );

    function makeSpherePositions( segmentsAround, segmentsDown ) {

        const numVertices = segmentsAround * segmentsDown * 6;
        const numComponents = 3;
        const positions = new Float32Array( numVertices * numComponents );
        const indices = [];

        const longHelper = new THREE.Object3D();
        const latHelper = new THREE.Object3D();
        const pointHelper = new THREE.Object3D();
        longHelper.add( latHelper );
        latHelper.add( pointHelper );
        pointHelper.position.z = 1;
        const temp = new THREE.Vector3();

        function getPoint( lat, long ) {

            latHelper.rotation.x = lat;
            longHelper.rotation.y = long;
            longHelper.updateMatrixWorld( true );
            return pointHelper.getWorldPosition( temp ).toArray();

        }

        let posNdx = 0;
        let ndx = 0;
        for ( let down = 0; down < segmentsDown; ++ down ) {

            const v0 = down / segmentsDown;
            const v1 = ( down + 1 ) / segmentsDown;
            const lat0 = ( v0 - 0.5 ) * Math.PI;
            const lat1 = ( v1 - 0.5 ) * Math.PI;

            for ( let across = 0; across < segmentsAround; ++ across ) {

                const u0 = across / segmentsAround;
                const u1 = ( across + 1 ) / segmentsAround;
                const long0 = u0 * Math.PI * 2;
                const long1 = u1 * Math.PI * 2;

                positions.set( getPoint( lat0, long0 ), posNdx ); posNdx += numComponents;
                positions.set( getPoint( lat1, long0 ), posNdx ); posNdx += numComponents;
                positions.set( getPoint( lat0, long1 ), posNdx ); posNdx += numComponents;
                positions.set( getPoint( lat1, long1 ), posNdx ); posNdx += numComponents;

                indices.push(
                    ndx, ndx + 1, ndx + 2,
                    ndx + 2, ndx + 1, ndx + 3,
                );
                ndx += 4;

            }

        }

        return { positions, indices };

    }

    const segmentsAround = 24;
    const segmentsDown = 16;
    const { positions, indices } = makeSpherePositions( segmentsAround, segmentsDown );

    const normals = positions.slice();

    const geometry = new THREE.BufferGeometry();
    const positionNumComponents = 3;
    const normalNumComponents = 3;

    const positionAttribute = new THREE.BufferAttribute( positions, positionNumComponents );
    positionAttribute.setUsage( THREE.DynamicDrawUsage );
    geometry.setAttribute(
        'position',
        positionAttribute );
    geometry.setAttribute(
        'normal',
        new THREE.BufferAttribute( normals, normalNumComponents ) );
    geometry.setIndex( indices );

    function makeInstance( geometry, color, x ) {

        const material = new THREE.MeshPhongMaterial( {
            color,
            side: THREE.DoubleSide,
            shininess: 100,
        } );

        const cube = new THREE.Mesh( geometry, material );
        scene.add( cube );

        cube.position.x = x;
        return cube;

    }

    const cubes = [
        makeInstance( geometry, 0xFF0000, 0 ),
    ];

    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;

    }

    const temp = new THREE.Vector3();

    function render( time ) {

        time *= 0.001;

        if ( resizeRendererToDisplaySize( renderer ) ) {

            const canvas = renderer.domElement;
            camera.aspect = canvas.clientWidth / canvas.clientHeight;
            camera.updateProjectionMatrix();

        }

        for ( let i = 0; i < positions.length; i += 3 ) {

            const quad = ( i / 12 | 0 );
            const ringId = quad / segmentsAround | 0;
            const ringQuadId = quad % segmentsAround;
            const ringU = ringQuadId / segmentsAround;
            const angle = ringU * Math.PI * 2;
            temp.fromArray( normals, i );
            temp.multiplyScalar( THREE.MathUtils.lerp( 1, 1.4, Math.sin( time + ringId + angle ) * .5 + .5 ) );
            temp.toArray( positions, i );

        }

        positionAttribute.needsUpdate = true;

        cubes.forEach( ( cube, ndx ) => {

            const speed = - 0.2 + ndx * .1;
            const rot = time * speed;
            cube.rotation.y = rot;

        } );

        renderer.render( scene, camera );

        requestAnimationFrame( render );

    }

    requestAnimationFrame( render );

}

main();

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