小程序中使用three.js

目前小程序支持了webgl, 同时项目中有相关3D展示的需求，所以考虑将three.js移植到小程序中。
但是小程序里面没有浏览器相关的运行环境如 window，document等。要想在小程序中使用three.js需要使用相应的移植版本。https://github.com/yannliao/three.js实现了一个在 three.js 的基本移植版, 目前测试支持了 包含 BoxBufferGeometry, CircleBufferGeometry, ConeBufferGeometry, CylinderBufferGeometry, DodecahedronBufferGeometry 等基本模型，OrbitControl， GTLFLoader, OBJLoader等。

使用

下载https://github.com/yannliao/three.js项目中build目录下的three.weapp.min.js到小程序相应目录，如：

在index.wxml中加入canvas组件, 其中需要手动绑定相应的事件，用于手势控制。

<view style="height: 100%; width: 100%;" bindtouchstart="documentTouchStart" bindtouchmove="documentTouchMove" bindtouchend="documentTouchEnd" >
    <canvas type="webgl" id="c" style="width: 100%; height:100%;" bindtouchstart="touchStart" bindtouchmove="touchMove" bindtouchend="touchEnd" bindtouchcancel="touchCancel" bindlongtap="longTap" bindtap="tap"></canvas>
</view>

在页面中引用three.js 和相应的Loader：

import * as THREE from '../../libs/three.weapp.min.js'
import { OrbitControls } from '../../jsm/loaders/OrbitControls'

在onLoad中获取canvas对象并注册到THREE.global中,THREE.global.registerCanvas可以传入id, 用于通过THREE.global.document.getElementById找到, 如果不传id默认使用canvas对象中的_canvasID, registerCanvas同时也会将该canvas选为当前使用canvas对象. 同时请在onUnload回调中注销canvas对象. 注意: THREE.global 中最多同时注册 5 个canvas对象, 并可以通过id找到. 注册的canvas对象, 会长驻内存, 如果不及时清理可能造成内存问题. THREE.global为three.js 的运行环境, 类似于浏览器中的window.

Page({
    data: {
        canvasId: ''
    },
    onLoad: function () {
        wx.createSelectorQuery()
        .select('#c')
        .node()
        .exec((res) => {
            const canvas = THREE.global.registerCanvas(res[0].node)
            this.setData({ canvasId: canvas._canvasId })
            // const canvas = THREE.global.registerCanvas('id_123', res[0].node)
            // canvas代码
        })
    },
    onUnload: function () {
        THREE.global.unregisterCanvas(this.data.canvasId)
        // THREE.global.unregisterCanvas(res[0].node)
        // THREE.global.clearCanvas()
    },

注册相关touch事件. 由于小程序架构原因, 需要手动绑定事件到THREE.global.canvas或者THREE.global.document上. 可以使用THREE.global.touchEventHandlerFactory('canvas', 'touchstart') 生成小程序的事件回调函数，触发默认canvas对象上的touch事件.

{
  touchStart(e) {
    console.log('canvas', e)
    THREE.global.touchEventHandlerFactory('canvas', 'touchstart')(e)
  },
  touchMove(e) {
    console.log('canvas', e)
    THREE.global.touchEventHandlerFactory('canvas', 'touchmove')(e)
  },
  touchEnd(e) {
    console.log('canvas', e)
    THREE.global.touchEventHandlerFactory('canvas', 'touchend')(e)
  },
}

编写three.js代码, 小程序运行环境中没有requestAnimationFrame, 目前可以使用canvas.requestAnimationFrame之后会将requestAnimationFrame注入到THREE.global中.

const camera = new THREE.PerspectiveCamera(70, canvas.width / canvas.height, 1, 1000);
camera.position.z = 500;
const scene = new THREE.Scene();
scene.background = new THREE.Color(0xAAAAAA);
const renderer = new THREE.WebGLRenderer({ antialias: true });

const controls = new OrbitControls(camera, renderer.domElement);
// controls.enableDamping = true;
// controls.dampingFactor = 0.25;
// controls.enableZoom = false;
camera.position.set(200, 200, 500);
controls.update();
const geometry = new THREE.BoxBufferGeometry(200, 200, 200);

const texture = new THREE.TextureLoader().load('./pikachu.png');
const material = new THREE.MeshBasicMaterial({ map: texture });

// const material = new THREE.MeshBasicMaterial({ color: 0x44aa88 });
const mesh = new THREE.Mesh(geometry, material);
scene.add(mesh);

// renderer.setPixelRatio(wx.getSystemInfoSync().pixelRatio);
// renderer.setSize(canvas.width, canvas.height);

function onWindowResize() {
    camera.aspect = window.innerWidth / window.innerHeight;
    camera.updateProjectionMatrix();
    renderer.setSize(canvas.width, canvas.height);
}
function render() {
    canvas.requestAnimationFrame(render);
    // mesh.rotation.x += 0.005;
    // mesh.rotation.y += 0.01;
    controls.update();
    renderer.render(scene, camera);
}

render()

完整示例:

index.js

import * as THREE from '../../libs/three.weapp.min.js'
import { OrbitControls } from '../../jsm/loaders/OrbitControls'

Page({
  data: {},
  onLoad: function () {
    wx.createSelectorQuery()
      .select('#c')
      .node()
      .exec((res) => {
        const canvas = THREE.global.registerCanvas(res[0].node)
        
        this.setData({ canvasId: canvas._canvasId })

        const camera = new THREE.PerspectiveCamera(70, canvas.width / canvas.height, 1, 1000);
        camera.position.z = 500;
        const scene = new THREE.Scene();
        scene.background = new THREE.Color(0xAAAAAA);
        const renderer = new THREE.WebGLRenderer({ antialias: true });
      
        const controls = new OrbitControls(camera, renderer.domElement);
        // controls.enableDamping = true;
        // controls.dampingFactor = 0.25;
        // controls.enableZoom = false;
        camera.position.set(200, 200, 500);
        controls.update();
        const geometry = new THREE.BoxBufferGeometry(200, 200, 200);
      
        const texture = new THREE.TextureLoader().load('./pikachu.png');
        const material = new THREE.MeshBasicMaterial({ map: texture });
      
        // const material = new THREE.MeshBasicMaterial({ color: 0x44aa88 });
        const mesh = new THREE.Mesh(geometry, material);
        scene.add(mesh);
      
        // renderer.setPixelRatio(wx.getSystemInfoSync().pixelRatio);
        // renderer.setSize(canvas.width, canvas.height);
      
        function onWindowResize() {
          camera.aspect = window.innerWidth / window.innerHeight;
          camera.updateProjectionMatrix();
          renderer.setSize(canvas.width, canvas.height);
        }
        function render() {
          canvas.requestAnimationFrame(render);
          // mesh.rotation.x += 0.005;
          // mesh.rotation.y += 0.01;
          controls.update();
          renderer.render(scene, camera);
        }

        render()

      })
  },
  onUnload: function () {
    THREE.global.unregisterCanvas(this.data.canvasId)
  },
  touchStart(e) {
    console.log('canvas', e)
    THREE.global.touchEventHandlerFactory('canvas', 'touchstart')(e)
  },
  touchMove(e) {
    console.log('canvas', e)
    THREE.global.touchEventHandlerFactory('canvas', 'touchmove')(e)
  },
  touchEnd(e) {
    console.log('canvas', e)
    THREE.global.touchEventHandlerFactory('canvas', 'touchend')(e)
  },
  touchCancel(e) {
    // console.log('canvas', e)
  },
  longTap(e) {
    // console.log('canvas', e)
  },
  tap(e) {
    // console.log('canvas', e)
  },
  documentTouchStart(e) {
    // console.log('document',e)
  },
  documentTouchMove(e) {
    // console.log('document',e)
  },
  documentTouchEnd(e) {
    // console.log('document',e)
  },
})

index.wxml

<view style="height: 100%; width: 100%;" bindtouchstart="documentTouchStart" bindtouchmove="documentTouchMove" bindtouchend="documentTouchEnd" >
    <canvas type="webgl" id="c" style="width: 100%; height:100%;" bindtouchstart="touchStart" bindtouchmove="touchMove" bindtouchend="touchEnd" bindtouchcancel="touchCancel" bindlongtap="longTap" bindtap="tap"></canvas>
</view>

其他

全部示例在 https://github.com/yannliao/threejs-example

three.js 库 https://github.com/yannliao/three.js

loader 组件在 threejs-example 中的 jsm 目录中

欢迎提交PR和issue