首先，不再废话了，什么是three.js，是干什么的，知道的就是知道，不知道的就百度吧。
昨儿发现three.js中的3D视野的缩小和放大效果可以用照相机的远近焦来实现。 
缩小后： 
这里采用的是透视照相机:
//照相机配置在这里可以改变fov的值，并更新这个照相机就可以了。
var fov = 40;//拍摄距离
var near = 1;//最小范围
var far = 1000;//最大范围
var camera = new THREE.PerspectiveCamera(fov, window.innerWidth / window.innerHeight, near, far);
camera.fov = fov;//fov是变量哦
camera.updateProjectionMatrix();
renderer.render(scene, camera);
另外：咱们都是习惯用鼠标上下滑轮实现放大缩小效果，so看代码
canvas.addEventListener('mousewheel', mousewheel, false);
//鼠标滑轮整体代码如下（旋转、放大缩小）：
function mousewheel(e) {
e.preventDefault();
//e.stopPropagation();
if (e.wheelDelta) { //判断浏览器IE，谷歌滑轮事件
if (e.wheelDelta > 0) { //当滑轮向上滚动时
fov -= (near < fov ? 1 : 0);
}
if (e.wheelDelta < 0) { //当滑轮向下滚动时
fov += (fov < far ? 1 : 0);
}
} else if (e.detail) { //Firefox滑轮事件
if (e.detail > 0) { //当滑轮向上滚动时
fov -= 1;
}
if (e.detail < 0) { //当滑轮向下滚动时
fov += 1;
}
}
camera.fov = fov;
camera.updateProjectionMatrix();
renderer.render(scene, camera);
//updateinfo();
}
<!DOCTYPE HTML>
<html lang="en">
<head>
<title>three.js 旋转 canvas - geometry - cube</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width; initial-scale=1.0; maximum-scale=1.0; user-scalable=0;"/>
<style type="text/css">
body {
font-family: Monospace;
background-color: #f0f0f0;
margin: 0px;
overflow: hidden;
}
</style>
</head>
<body>
<script type="text/javascript" src="../build/Three.js"></script>
<script type="text/javascript" src="js/RequestAnimationFrame.js"></script>
<script type="text/javascript" src="js/Stats.js"></script>
<script type="text/javascript">
var container, stats;
var camera, scene, renderer;
var cube, plane;
var targetRotation = 0;
var targetRotationOnMouseDown = 0;
var mouseX = 0;
var mouseXOnMouseDown = 0;
var windowHalfX = window.innerWidth / 2;
var windowHalfY = window.innerHeight / 2;
init();
animate();
var fov = 40;
var near = 1;//最小范围
var far = 1000;//最大范围
function init() {
container = document.createElement( 'div' );
document.body.appendChild( container );
var info = document.createElement( 'div' );
info.style.position = 'absolute';
info.style.top = '10px';
info.style.width = '100%';
info.style.textAlign = 'center';
info.innerHTML = 'Drag to spin the cube';
container.appendChild( info );
camera = new THREE.Camera( 70, window.innerWidth / window.innerHeight, near, far );
camera.fov = fov;
camera.position.y = 150;
camera.position.z = 500;
camera.target.position.y = 150;
scene = new THREE.Scene();
// Cube
var materials = [];
for ( var i = 0; i < 6; i ++ ) {
materials.push( [ new THREE.MeshBasicMaterial( { color: Math.random() * 0xffffff } ) ] );
}
cube = new THREE.Mesh( new THREE.CubeGeometry( 200, 200, 200, 1, 1, 1, materials ), new THREE.MeshFaceMaterial() );
cube.position.y = 150;
cube.overdraw = true;
scene.addObject( cube );
// Plane
plane = new THREE.Mesh( new THREE.PlaneGeometry( 200, 200 ), new THREE.MeshBasicMaterial( { color: 0xe0e0e0 } ) );
plane.rotation.x = - 90 * ( Math.PI / 180 );
plane.overdraw = true;
scene.addObject( plane );
renderer = new THREE.CanvasRenderer();
renderer.setSize( window.innerWidth, window.innerHeight );
container.appendChild( renderer.domElement );
stats = new Stats();
stats.domElement.style.position = 'absolute';
stats.domElement.style.top = '0px';
container.appendChild( stats.domElement );
document.addEventListener( 'mousedown', onDocumentMouseDown, false );
document.addEventListener( 'touchstart', onDocumentTouchStart, false );
document.addEventListener( 'touchmove', onDocumentTouchMove, false );
document.addEventListener( 'mousewheel', mousewheel, false );
}
//
function mousewheel(e) {
e.preventDefault();
//e.stopPropagation();
if (e.wheelDelta) { //判断浏览器IE，谷歌滑轮事件
if (e.wheelDelta > 0) { //当滑轮向上滚动时
fov -= (near < fov ? 1 : 0);
}
if (e.wheelDelta < 0) { //当滑轮向下滚动时
fov += (fov < far ? 1 : 0);
}
} else if (e.detail) { //Firefox滑轮事件
if (e.detail > 0) { //当滑轮向上滚动时
fov -= 1;
}
if (e.detail < 0) { //当滑轮向下滚动时
fov += 1;
}
}
camera.fov = fov;
camera.updateProjectionMatrix();
renderer.render(scene, camera);
//updateinfo();
}
function onDocumentMouseDown( event ) {//按下鼠标
event.preventDefault();
//鼠标监听
document.addEventListener( 'mousemove', onDocumentMouseMove, false );
document.addEventListener( 'mouseup', onDocumentMouseUp, false );
document.addEventListener( 'mouseout', onDocumentMouseOut, false );
mouseXOnMouseDown = event.clientX - windowHalfX;
targetRotationOnMouseDown = targetRotation;
}
function onDocumentMouseMove( event ) {//移动鼠标
mouseX = event.clientX - windowHalfX;
targetRotation = targetRotationOnMouseDown + ( mouseX - mouseXOnMouseDown ) * 0.02;
}
function onDocumentMouseUp( event ) {//释放鼠标键
document.removeEventListener( 'mousemove', onDocumentMouseMove, false );
document.removeEventListener( 'mouseup', onDocumentMouseUp, false );
document.removeEventListener( 'mouseout', onDocumentMouseOut, false );
}
function onDocumentMouseOut( event ) {//移走鼠标
document.removeEventListener( 'mousemove', onDocumentMouseMove, false );
document.removeEventListener( 'mouseup', onDocumentMouseUp, false );
document.removeEventListener( 'mouseout', onDocumentMouseOut, false );
}
function onDocumentTouchStart( event ) {
if ( event.touches.length == 1 ) {
event.preventDefault();
mouseXOnMouseDown = event.touches[ 0 ].pageX - windowHalfX;
targetRotationOnMouseDown = targetRotation;
}
}
function onDocumentTouchMove( event ) {
if ( event.touches.length == 1 ) {
event.preventDefault();
mouseX = event.touches[ 0 ].pageX - windowHalfX;
targetRotation = targetRotationOnMouseDown + ( mouseX - mouseXOnMouseDown ) * 0.05;
}
}
//
function animate() {
requestAnimationFrame( animate );
render();
stats.update();
}
function render() {
plane.rotation.z = cube.rotation.y += ( targetRotation - cube.rotation.y ) * 0.05;
renderer.render( scene, camera );
}
</script>
</body>
</html>