学习threejs，使用canvas更新纹理

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文章目录

一、🍀前言
- 1.1 ☘️Texture 贴图
二、🍀使用canvas更新纹理
- 1. ☘️实现思路
- 2. ☘️代码样例

一、🍀前言

本文详细介绍如何基于threejs在三维场景中使用canvas更新纹理，亲测可用。希望能帮助到您。一起学习，加油！加油！

1.1 ☘️Texture 贴图

创建一个纹理贴图，将其应用到一个表面，或者作为反射/折射贴图。
构造函数：
Texture( image, mapping, wrapS, wrapT, magFilter, minFilter, format, type, anisotropy, encoding )
常用属性：
在这里插入图片描述
方法：

二、🍀使用canvas更新纹理

1. ☘️实现思路

1、初始化renderer渲染器
2、初始化Scene三维场景scene，创建THREE.CubeTextureLoader立方体纹理加载器cubeTextureLoader，加载cubeTextureLoader的六个方位的图片获取纹理对象cubeTexture，scene背景background设置为cubeTexture。
3、创建id为‘surface’的canvas页面元素火焰然后动画，并执行。具体实现参考下面代码样例。
4、初始化camera相机，定义相机位置 camera.position.set
5、初始化THREE.AmbientLight环境光源，scene场景加入环境光源，初始化THREE.DirectionalLight平行光源，设置平行光源位置，设置平行光源投影，scene添加平行光源。
6、加载几何模型：创建THREE.AxesHelper坐标辅助工具helper，scene场景中加入helper。创建THREE.BoxGeometry立方体几何体geometry，创建THREE.MeshBasicMaterial基础材质material，material设置map贴图（为步骤3canvas元素）、水平和垂直贴图包裹，传入geometry和material创建THREE.Mesh网格对象，scene中加入创建的网格对象。
7、加入controls控制，加入stats监控器，监控帧数信息。

2. ☘️代码样例

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>learn60(使用CANVAS更新纹理)</title>
    <script src="lib/threejs/127/three.js-master/build/three.js"></script>
    <script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script>
    <script src="lib/threejs/127/three.js-master/examples/js/controls/OrbitControls.js"></script>
    <script src="lib/threejs/127/three.js-master/examples/js/libs/stats.min.js"></script>
    <script src="lib/threejs/127/three.js-master/examples/js/libs/dat.gui.min.js"></script>
    <script src="lib/js/Detector.js"></script>
</head>
<style type="text/css">
    html, body {
        margin: 0;
        height: 100%;
    }

    canvas {
        display: block;
    }

    #surface {
        position: fixed;
        left: 0;
        bottom: 0;
    }
</style>
<body onload="draw()">
<canvas id="surface"></canvas>
</body>
<script>
  var renderer, camera, scene, gui, light, stats, controls

  //引入一个canvas动画
  function initCanvas() {
    $(document).ready(function () {

      // Set canvas drawing surface
      var space = document.getElementById("surface")
      var surface = space.getContext("2d")
      surface.scale(1, 1)

      // Set Particles
      var particles = []
      var particle_count = 150
      for (var i = 0; i < particle_count; i++) {
        particles.push(new particle())
      }
      var time = 0
      // Set wrapper and canvas items size
      var canvasWidth = 480
      var canvasHeight = 480
      $(".wrapper").css({width: canvasWidth, height: canvasHeight})
      $("#surface").css({width: canvasWidth, height: canvasHeight})

      // shim layer with setTimeout fallback from Paul Irish
      window.requestAnimFrame = (function () {
        return window.requestAnimationFrame ||
          window.webkitRequestAnimationFrame ||
          window.mozRequestAnimationFrame ||
          function (callback) {
            window.setTimeout(callback, 6000 / 60)
          }
      })()

      function particle() {

        this.speed = {x: -1 + Math.random() * 2, y: -5 + Math.random() * 5}
        canvasWidth = (document.getElementById("surface").width)
        canvasHeight = (document.getElementById("surface").height)
        this.location = {x: canvasWidth / 2, y: (canvasHeight / 2) + 35}

        this.radius = .5 + Math.random() * 1

        this.life = 10 + Math.random() * 10
        this.death = this.life

        this.r = 255
        this.g = Math.round(Math.random() * 155)
        this.b = 0
      }

      function ParticleAnimation() {
        surface.globalCompositeOperation = "source-over"
        surface.fillStyle = "black"
        surface.fillRect(0, 0, canvasWidth, canvasHeight)
        surface.globalCompositeOperation = "lighter"

        for (var i = 0; i < particles.length; i++) {
          var p = particles[i]

          surface.beginPath()

          p.opacity = Math.round(p.death / p.life * 100) / 100
          var gradient = surface.createRadialGradient(p.location.x, p.location.y, 0, p.location.x, p.location.y, p.radius)
          gradient.addColorStop(0, "rgba(" + p.r + ", " + p.g + ", " + p.b + ", " + p.opacity + ")")
          gradient.addColorStop(0.5, "rgba(" + p.r + ", " + p.g + ", " + p.b + ", " + p.opacity + ")")
          gradient.addColorStop(1, "rgba(" + p.r + ", " + p.g + ", " + p.b + ", 0)")
          surface.fillStyle = gradient
          surface.arc(p.location.x, p.location.y, p.radius, Math.PI * 2, false)
          surface.fill()
          p.death--
          p.radius++
          p.location.x += (p.speed.x)
          p.location.y += (p.speed.y)

          //regenerate particles
          if (p.death < 0 || p.radius < 0) {
            //a brand new particle replacing the dead one
            particles[i] = new particle()
          }
        }

        requestAnimFrame(ParticleAnimation)

      }

      ParticleAnimation()

    })
  }

  var initRender = () => {
    renderer = new THREE.WebGLRenderer({antialias: true})
    renderer.setClearColor(0xeeeeee)
    renderer.setSize(window.innerWidth, window.innerHeight)
    renderer.shadowMap.enabled = true
    renderer.setPixelRatio(window.devicePixelRatio)
    document.body.appendChild(renderer.domElement)
  }

  var initCamera = () => {
    camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000)
    camera.position.set(0, 0, 15)
  }

  var initScene = () => {
    var cubeTextureLoader = new THREE.CubeTextureLoader()
    cubeTextureLoader.setPath('data/texture/skybox/space/')
    var cubeTexture = cubeTextureLoader.load([
      'right.jpg', 'left.jpg',
      'top.jpg', 'bottom.jpg',
      'front.jpg', 'back.jpg'
    ])
    scene = new THREE.Scene()
    scene.background = cubeTexture
  }

  var initLight = () => {
    scene.add(new THREE.AmbientLight(0x444444))

    light = new THREE.DirectionalLight(0xffffff)
    light.position.set(0, 20, 20)
    light.castShadow = true
    scene.add(light)
  }

  var initModel = () => {
    var helper = new THREE.AxesHelper(50)
    scene.add(helper)

    var geometry = new THREE.BoxBufferGeometry(5, 5, 5)
    var canvas = $('#surface')[0]
    var texture = new THREE.Texture(canvas)
    material = new THREE.MeshBasicMaterial({map: texture})
    scene.add(new THREE.Mesh(geometry, material))
  }

  var initStats = () => {
    stats = new Stats()
    document.body.appendChild(stats.dom)
  }

  var initControls = () => {
    controls = new THREE.OrbitControls(camera, renderer.domElement)
    controls.enableDamping = true
  }

  var render = () => {
    material.map.needsUpdate = true
    renderer.render(scene, camera)
  }

  var onWindowResize = () => {
    camera.aspect = window.innerWidth / window.innerHeight
    camera.updateProjectionMatrix()
    renderer.setSize(window.innerWidth, window.innerHeight)
  }

  var animate = () => {
    render()
    stats.update()
    controls.update()
    requestAnimationFrame(animate)
  }

  var draw = () => {
    if(!Detector.webgl)Detector.addGetWebGLMessage()
    initCanvas()
    initRender()
    initScene()
    initCamera()
    initLight()
    initModel()
    initStats()
    initControls()

    animate()

    window.onresize = onWindowResize
  }
</script>
</html>