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👨⚕️ 收录于专栏：threejs gis工程师
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：
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>
效果如下：
