前端开发three.js简介 —— 3D框架

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随着HTML5的普及,网页的表现能力越来越强大,浏览器提供了WebGL接口,可以通过调用对应API进行3D图形的绘制,Three.js在这些基础接口之上又做了一层封装。

动画效果:

html 代码

<!DOCTYPE html>
<html lang=”en”>
    <head>
        <meta charset=”UTF-8″ />
        <title>Bestvist | threejs-cat</title>
        <meta name=”keywords” content=”THREEJS,javascript” />
        <meta
            name=”description”
            content=”随着HTML5的普及,网页的表现能力越来越强大,浏览器提供了WebGL接口,可以通过调用对应API进行3D图形的绘制,Three.js在这些基础接口之上又做了一层封装。”
        />
        <link
            rel=”stylesheet”
            href=”https://cdnjs.cloudflare.com/ajax/libs/meyer-reset/2.0/reset.min.css
        />
        <style>
            @import url(https://fonts.googleapis.com/css?family=Open+Sans:800);
            #world {
                position: absolute;
                width: 100%;
                height: 100%;
                background-color: #6ecccc;
                overflow: hidden;
            }
            #doc {
                position: absolute;
                width: 100%;
                margin: auto;
                bottom: 0;
                margin-bottom: 20px;
                font-family: ‘Open Sans’, sans-serif;
                color: #328685;
                font-size: 0.7em;
                text-transform: uppercase;
                text-align: center;
            }
            #doc a {
                color: #328685;
            }
            #doc a:hover {
                color: #630d15;
            }
        </style>
    </head>
    <body>
        <div id=”world”></div>
        <div id=”doc”>
            <a href=”http://www.bestvist.com/2017/12/25/threejs/”
                >Three.js简介</a
            >
        </div>
        <script src=”http://cdnjs.cloudflare.com/ajax/libs/three.js/r70/three.min.js”></script>
        <script src=”http://cdnjs.cloudflare.com/ajax/libs/gsap/1.16.1/TweenMax.min.js”></script>
        <script src=”https://s3-us-west-2.amazonaws.com/s.cdpn.io/264161/OrbitControls.js”></script>
        <script src=”https://s3-us-west-2.amazonaws.com/s.cdpn.io/264161/Cat.js”></script>
        <script>
            //THREEJS RELATED VARIABLES
            var scene,
                camera,
                fieldOfView,
                aspectRatio,
                nearPlane,
                farPlane,
                gobalLight,
                shadowLight,
                backLight,
                renderer,
                container,
                controls
            //SCREEN & MOUSE VARIABLES
            var HEIGHT,
                WIDTH,
                windowHalfX,
                windowHalfY,
                mousePos = {
                    x: 0,
                    y: 0,
                },
                oldMousePos = {
                    x: 0,
                    y: 0,
                },
                ballWallDepth = 28
            //3D OBJECTS VARIABLES
            var hero
            //INIT THREE JS, SCREEN AND MOUSE EVENTS
            function initScreenAnd3D() {
                HEIGHT = window.innerHeight
                WIDTH = window.innerWidth
                windowHalfX = WIDTH / 2
                windowHalfY = HEIGHT / 2
                scene = new THREE.Scene()
                aspectRatio = WIDTH / HEIGHT
                fieldOfView = 50
                nearPlane = 1
                farPlane = 2000
                camera = new THREE.PerspectiveCamera(
                    fieldOfView,
                    aspectRatio,
                    nearPlane,
                    farPlane,
                )
                camera.position.x = 0
                camera.position.z = 300
                camera.position.y = 250
                camera.lookAt(new THREE.Vector3(0, 60, 0))
                renderer = new THREE.WebGLRenderer({
                    alpha: true,
                    antialias: true,
                })
                renderer.setPixelRatio(window.devicePixelRatio)
                renderer.setSize(WIDTH, HEIGHT)
                renderer.shadowMapEnabled = true
                container = document.getElementById(‘world’)
                container.appendChild(renderer.domElement)
                window.addEventListener(‘resize’, handleWindowResize, false)
                document.addEventListener(‘mousemove’, handleMouseMove, false)
                document.addEventListener(‘touchmove’, handleTouchMove, false)
            }
            function handleWindowResize() {
                HEIGHT = window.innerHeight
                WIDTH = window.innerWidth
                windowHalfX = WIDTH / 2
                windowHalfY = HEIGHT / 2
                renderer.setSize(WIDTH, HEIGHT)
                camera.aspect = WIDTH / HEIGHT
                camera.updateProjectionMatrix()
            }
            function handleMouseMove(event) {
                mousePos = {
                    x: event.clientX,
                    y: event.clientY,
                }
            }
            function handleTouchMove(event) {
                if (event.touches.length == 1) {
                    event.preventDefault()
                    mousePos = {
                        x: event.touches[0].pageX,
                        y: event.touches[0].pageY,
                    }
                }
            }
            function createLights() {
                globalLight = new THREE.HemisphereLight(0xffffff, 0xffffff, 0.5)
                shadowLight = new THREE.DirectionalLight(0xffffff, 0.9)
                shadowLight.position.set(200, 200, 200)
                shadowLight.castShadow = true
                shadowLight.shadowDarkness = 0.2
                shadowLight.shadowMapWidth = shadowLight.shadowMapHeight = 2048
                backLight = new THREE.DirectionalLight(0xffffff, 0.4)
                backLight.position.set(-100, 100, 100)
                backLight.castShadow = true
                backLight.shadowDarkness = 0.1
                backLight.shadowMapWidth = shadowLight.shadowMapHeight = 2048
                scene.add(globalLight)
                scene.add(shadowLight)
                scene.add(backLight)
            }
            function createFloor() {
                floor = new THREE.Mesh(
                    new THREE.PlaneBufferGeometry(1000, 1000),
                    new THREE.MeshBasicMaterial({
                        color: 0x6ecccc,
                    }),
                )
                floor.rotation.x = -Math.PI / 2
                floor.position.y = 0
                floor.receiveShadow = true
                scene.add(floor)
            }
            function createHero() {
                hero = new Cat()
                scene.add(hero.threeGroup)
            }
            function createBall() {
                ball = new Ball()
                scene.add(ball.threeGroup)
            }
            // BALL RELATED CODE
            var woolNodes = 10,
                woolSegLength = 2,
                gravity = -0.8,
                accuracy = 1
            Ball = function() {
                var redMat = new THREE.MeshLambertMaterial({
                    color: 0x630d15,
                    shading: THREE.FlatShading,
                })
                var stringMat = new THREE.LineBasicMaterial({
                    color: 0x630d15,
                    linewidth: 3,
                })
                this.threeGroup = new THREE.Group()
                this.ballRay = 8
                this.verts = []
                // string
                var stringGeom = new THREE.Geometry()
                for (var i = 0; i < woolNodes; i++) {
                    var v = new THREE.Vector3(0, -i * woolSegLength, 0)
                    stringGeom.vertices.push(v)
                    var woolV = new WoolVert()
                    woolV.x = woolV.oldx = v.x
                    woolV.y = woolV.oldy = v.y
                    woolV.z = 0
                    woolV.fx = woolV.fy = 0
                    woolV.isRootNode = i == 0
                    woolV.vertex = v
                    if (i > 0) woolV.attach(this.verts[i – 1])
                    this.verts.push(woolV)
                }
                this.string = new THREE.Line(stringGeom, stringMat)
                // body
                var bodyGeom = new THREE.SphereGeometry(this.ballRay, 5, 4)
                this.body = new THREE.Mesh(bodyGeom, redMat)
                this.body.position.y = -woolSegLength * woolNodes
                var wireGeom = new THREE.TorusGeometry(
                    this.ballRay,
                    0.5,
                    3,
                    10,
                    Math.PI * 2,
                )
                this.wire1 = new THREE.Mesh(wireGeom, redMat)
                this.wire1.position.x = 1
                this.wire1.rotation.x = -Math.PI / 4
                this.wire2 = this.wire1.clone()
                this.wire2.position.y = 1
                this.wire2.position.x = -1
                this.wire1.rotation.x = -Math.PI / 4 + 0.5
                this.wire1.rotation.y = -Math.PI / 6
                this.wire3 = this.wire1.clone()
                this.wire3.rotation.x = -Math.PI / 2 + 0.3
                this.wire4 = this.wire1.clone()
                this.wire4.position.x = -1
                this.wire4.rotation.x = -Math.PI / 2 + 0.7
                this.wire5 = this.wire1.clone()
                this.wire5.position.x = 2
                this.wire5.rotation.x = -Math.PI / 2 + 1
                this.wire6 = this.wire1.clone()
                this.wire6.position.x = 2
                this.wire6.position.z = 1
                this.wire6.rotation.x = 1
                this.wire7 = this.wire1.clone()
                this.wire7.position.x = 1.5
                this.wire7.rotation.x = 1.1
                this.wire8 = this.wire1.clone()
                this.wire8.position.x = 1
                this.wire8.rotation.x = 1.3
                this.wire9 = this.wire1.clone()
                this.wire9.scale.set(1.2, 1.1, 1.1)
                this.wire9.rotation.z = Math.PI / 2
                this.wire9.rotation.y = Math.PI / 2
                this.wire9.position.y = 1
                this.body.add(this.wire1)
                this.body.add(this.wire2)
                this.body.add(this.wire3)
                this.body.add(this.wire4)
                this.body.add(this.wire5)
                this.body.add(this.wire6)
                this.body.add(this.wire7)
                this.body.add(this.wire8)
                this.body.add(this.wire9)
                this.threeGroup.add(this.string)
                this.threeGroup.add(this.body)
                this.threeGroup.traverse(function(object) {
                    if (object instanceof THREE.Mesh) {
                        object.castShadow = true
                        object.receiveShadow = true
                    }
                })
            }
            /*
The next part of the code is largely inspired by this codepen :
https://codepen.io/dissimulate/pen/KrAwx?editors=001
thanks to dissimulate for his great work
*/
            /*
Copyright (c) 2013 dissimulate at Codepen
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the “Software”), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/
            WoolVert = function() {
                this.x = 0
                this.y = 0
                this.z = 0
                this.oldx = 0
                this.oldy = 0
                this.fx = 0
                this.fy = 0
                this.isRootNode = false
                this.constraints = []
                this.vertex = null
            }
            WoolVert.prototype.update = function() {
                var wind = 0 //.1+Math.random()*.5;
                this.add_force(wind, gravity)
                nx = this.x + (this.x – this.oldx) * 0.9 + this.fx
                ny = this.y + (this.y – this.oldy) * 0.9 + this.fy
                this.oldx = this.x
                this.oldy = this.y
                this.x = nx
                this.y = ny
                this.vertex.x = this.x
                this.vertex.y = this.y
                this.vertex.z = this.z
                this.fy = this.fx = 0
            }
            WoolVert.prototype.attach = function(point) {
                this.constraints.push(new Constraint(this, point))
            }
            WoolVert.prototype.add_force = function(x, y) {
                this.fx += x
                this.fy += y
            }
            Constraint = function(p1, p2) {
                this.p1 = p1
                this.p2 = p2
                this.length = woolSegLength
            }
            Ball.prototype.update = function(posX, posY, posZ) {
                var i = accuracy
                while (i–) {
                    var nodesCount = woolNodes
                    while (nodesCount–) {
                        var v = this.verts[nodesCount]
                        if (v.isRootNode) {
                            v.x = posX
                            v.y = posY
                            v.z = posZ
                        } else {
                            var constraintsCount = v.constraints.length
                            while (constraintsCount–) {
                                var c = v.constraints[constraintsCount]
                                var diff_x = c.p1.x – c.p2.x,
                                    diff_y = c.p1.y – c.p2.y,
                                    dist = Math.sqrt(
                                        diff_x * diff_x + diff_y * diff_y,
                                    ),
                                    diff = (c.length – dist) / dist
                                var px = diff_x * diff * 0.5
                                var py = diff_y * diff * 0.5
                                c.p1.x += px
                                c.p1.y += py
                                c.p2.x -= px
                                c.p2.y -= py
                                c.p1.z = c.p2.z = posZ
                            }
                            if (nodesCount == woolNodes – 1) {
                                this.body.position.x = this.verts[nodesCount].x
                                this.body.position.y = this.verts[nodesCount].y
                                this.body.position.z = this.verts[nodesCount].z
                                this.body.rotation.z +=
                                    v.y <= this.ballRay
                                        ? (v.oldx – v.x) / 10
                                        : Math.min(
                                                Math.max(diff_x / 2, -0.1),
                                                0.1,
                                         )
                            }
                        }
                        if (v.y < this.ballRay) {
                            v.y = this.ballRay
                        }
                    }
                }
                nodesCount = woolNodes
                while (nodesCount–) this.verts[nodesCount].update()
                this.string.geometry.verticesNeedUpdate = true
            }
            Ball.prototype.receivePower = function(tp) {
                this.verts[woolNodes – 1].add_force(tp.x, tp.y)
            }
            // Enf of the code inspired by dissmulate
            // Make everything work together :
            var t = 0
            function loop() {
                render()
                t += 0.05
                hero.updateTail(t)
                var ballPos = getBallPos()
                ball.update(ballPos.x, ballPos.y, ballPos.z)
                ball.receivePower(hero.transferPower)
                hero.interactWithBall(ball.body.position)
                requestAnimationFrame(loop)
            }
            function getBallPos() {
                var vector = new THREE.Vector3()
                vector.set(
                    (mousePos.x / window.innerWidth) * 2 – 1,
                    -(mousePos.y / window.innerHeight) * 2 + 1,
                    0.1,
                )
                vector.unproject(camera)
                var dir = vector.sub(camera.position).normalize()
                var distance = (ballWallDepth – camera.position.z) / dir.z
                var pos = camera.position
                    .clone()
                    .add(dir.multiplyScalar(distance))
                return pos
            }
            function render() {
                if (controls) controls.update()
                renderer.render(scene, camera)
            }
            window.addEventListener(‘load’, init, false)
            function init(event) {
                initScreenAnd3D()
                createLights()
                createFloor()
                createHero()
                createBall()
                loop()
            }
        </script>
    </body>
</html>
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