开源加速了技术的发展,也让我们这些搞技术的人牺牲了大量的时间来更新新的技能。
Webgl算是比较新的东西了,他本身的库相当繁琐,你写一个三角形的面,或者一个立方体,都能把人搞疯。好在很多大牛写了很多方便实用的库。
Three.js库用的比较多,里面有几何,有渲染等等很多实用的库,下载地址:https://github.com/mrdoob/three.js
stats.js库用来监测程序性能,下载地址:https://github.com/mrdoob/stats.js
Tween.js库用来制作动画,下载地址:https://github.com/sole
下面的例子刚好用上了这三个库。
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Three框架</title> <script src="js/three.js"></script> <script src="js/stats.js"></script> <script src="js/Tween.js"></script> <style type="text/css"> div#canvas-frame { border: none; cursor: pointer; width: 100%; height: 600px; background-color: #EEEEEE; } </style> <script> function initTween() { new TWEEN.Tween(mesh.position) .to({ x: -400 }, 3000).repeat(Infinity).start(); } var renderer; var stats; function initThree() { width = document.getElementById('canvas-frame').clientWidth; height = document.getElementById('canvas-frame').clientHeight; renderer = new THREE.WebGLRenderer({ antialias: true }); renderer.setSize(width, height); document.getElementById('canvas-frame').appendChild(renderer.domElement); renderer.setClearColor(0xFFFFFF, 1.0); stats = new Stats(); stats.domElement.style.position = 'absolute'; stats.domElement.style.left = '0px'; stats.domElement.style.top = '0px'; document.getElementById('canvas-frame').appendChild(stats.domElement); } var camera; function initCamera() { camera = new THREE.PerspectiveCamera(45, width / height, 1, 10000); camera.position.x = 0; camera.position.y = 0; camera.position.z = 600; camera.up.x = 0; camera.up.y = 1; camera.up.z = 0; camera.lookAt(0,0,0); } var scene; function initScene() { scene = new THREE.Scene(); } var light; function initLight() { light = new THREE.AmbientLight(0xFF0000); light.position.set(100, 100, 200); scene.add(light); light = new THREE.PointLight(0x00FF00); light.position.set(0, 0, 300); scene.add(light); } var cube; var mesh; function initObject() { var geometry = new THREE.CylinderGeometry(100, 150, 400); var material = new THREE.MeshLambertMaterial({ color: 0xFFFFFF }); mesh = new THREE.Mesh(geometry, material); mesh.position = new THREE.Vector3(0, 0, 0); scene.add(mesh); } function threeStart() { initThree(); initCamera(); initScene(); initLight(); initObject(); animation(); initTween(); } function animation() { renderer.render(scene, camera); requestAnimationFrame(animation); stats.update(); TWEEN.update(); } </script> </head> <body onload="threeStart();"> <div id="canvas-frame"></div> </body> </html>
对于专业建模的人来说,几何部分最重要,所以下面重点补充几何部分。
对于这部分,如果单纯的只是看源码或者官网的英文,也要崩溃,对于我这种英语渣的,而且还偏偏在外企工作的人,那种糟糕的心情,想想也觉得恐怖。好在网络是一个很好的东西,这个Three.js的api中文版的帮助文档,你可以在这个链接查看:
http://techbrood.com/threejs/docs/
这里举几个例子
画一条直线:
function initObject() { var material = new THREE.LineBasicMaterial({ color: 0x0000ff }); var geometry = new THREE.Geometry(); geometry.vertices.push( new THREE.Vector3(-100, 0, 0), new THREE.Vector3(100, 0, 0) ); var line = new THREE.Line(geometry, material); scene.add(line); }
画一条椭圆线:
function initObject() { var curve = new THREE.EllipseCurve( 0, 0, // ax, aY 100, 20, // xRadius, yRadius 0, 2 * Math.PI, // aStartAngle, aEndAngle false, // aClockwise 0 // aRotation ); var path = new THREE.Path(curve.getPoints(50)); var geometry = path.createPointsGeometry(50); var material = new THREE.LineBasicMaterial({ color: 0xff0000 }); // Create the final Object3d to add to the scene var ellipse = new THREE.Line(geometry, material); scene.add(ellipse); }
圆曲线就比较简单了,只需要在上述代码的基础上,把x,y方向的半径修改成相等的值即可。
矩形就更简单了,实际上就是四条线组成的,都不用举例了。
接下来开始画简单的面:
1、矩形平面
function initObject() { var geometry = new THREE.PlaneGeometry(200, 200, 1,1); var material = new THREE.MeshBasicMaterial({ color: 0xffff00, side: THREE.DoubleSide }); var plane = new THREE.Mesh(geometry, material); scene.add(plane); }
2、圆形曲面
function initObject() { var geometry = new THREE.CircleGeometry(50,32); var material = new THREE.MeshLambertMaterial({ color: 0xFFFFFF }); mesh = new THREE.Mesh(geometry, material); mesh.position = new THREE.Vector3(0, 0, 0); scene.add(mesh); }
3、三角平面简单点可以通过圆来,即把三角形面改为1个,不过这个三角形是等腰三角形。
function initObject() { var geometry = new THREE.CircleGeometry(50,1); var material = new THREE.MeshLambertMaterial({ color: 0xFFFFFF }); mesh = new THREE.Mesh(geometry, material); mesh.position = new THREE.Vector3(0, 0, 0); scene.add(mesh); }
4、如果想画任意的形状的三角平面,即通过THREE.Shape().lineTo()添加点即可,同理,想画不同形状的平面,添加点即可:
function initObject() { var rectShape = new THREE.Shape(); rectShape.moveTo(0, 0); rectShape.lineTo(0, 100); rectShape.lineTo(150, 100); rectShape.lineTo(0, 0); var rectGeom = new THREE.ShapeGeometry(rectShape); var rectMesh = new THREE.Mesh(rectGeom, new THREE.MeshBasicMaterial({ color: 0xff0000 })); scene.add(rectMesh); }
线和面的问题解决了,接下来是体,体的话,也用现成的api来建:
1、首先是立方体:
function initObject() { var geometry = new THREE.BoxGeometry(100, 100, 100); var material = new THREE.MeshBasicMaterial({ color: 0x00ff00 }); var cube = new THREE.Mesh(geometry, material); scene.add(cube); }
2、接下来是锥体:
var geometry = new THREE.ConeGeometry(50, 200, 320); var material = new THREE.MeshBasicMaterial({ color: 0xffff00 }); var cone = new THREE.Mesh(geometry, material); scene.add(cone);
3、圆柱体:
function initObject() { var geometry = new THREE.CylinderGeometry(50, 50, 200, 32); var material = new THREE.MeshBasicMaterial({ color: 0xffff00 }); var cylinder = new THREE.Mesh(geometry, material); scene.add(cylinder); }
4、球体:
function initObject() { var geometry = new THREE.IcosahedronGeometry(100, 2); var material = new THREE.MeshBasicMaterial({ color: 0xffff00 }); var sphere = new THREE.Mesh(geometry, material); scene.add(sphere); }
就先举这些常规模型的例子,如果想实现更复杂的图形,可以查看Three.js的中文api说明。
其他的比如光照、贴图等基础知识,建议去看看webgl中文网的Three.js基础教程,其他一些api的应用,买买书看看就可以了,看看api的帮助也都可以,更高级的应用就需要自己实践和摸索了。