three.js之正投影摄像机与透视投影摄像机的区别

<!DOCTYPE html>

<html>

    <head>

        <meta charset="UTF-8">

        <title>Three框架</title>

        <script src="../static/three.js-master/build/three.js"></script>

        <style type="text/css">

            div#canvas-frame {

                border: none;

                cursor: pointer;

                width: 100%;

                height: 600px;

                background-color: #EEEEEE;

            }

        </style>

        <script>

            var renderer;  // 渲染器

            function initThree() {

                width = window.innerWidth;  // 宽度

                height = window.innerHeight;  // 长度

                renderer = new THREE.WebGLRenderer({

                    antialias : true  // 设置反锯齿

                });

                renderer.setSize(width, height);

                document.getElementById('canvas-frame').appendChild(renderer.domElement);

                renderer.setClearColor(0xFFFFFF, 1.0);

            }

            var camera;

            function initCamera() {

                camera = new THREE.PerspectiveCamera(45, width / height, 1, 10000);  // 透视投影摄像机

                // camera = new THREE.OrthographicCamera( window.innerWidth / - 2, window.innerWidth / 2, window.innerHeight / 2, window.innerHeight / - 2, 10, 1000 );  // 正投影摄像机

                camera.position.x = 0;  // 设置相机的坐标

                camera.position.y = 0;

                camera.position.z = 600;

                camera.up.x = 0;

                camera.up.y = 1;  // 设置相机的上为y轴方向

                camera.up.z = 0;

                camera.lookAt(0, 0, 0);  // 相机lookAt的点一定显示在屏幕的正中央：利用这点，我们可以实现物体移动时，我们可以一直跟踪物体，让物体永远在屏幕的中央

            }

            var scene;  // 创建场景

            function initScene() {

                scene = new THREE.Scene();

            }

            var light;  // 创建光源

            function initLight() {

                light = new THREE.AmbientLight(0xFF0000);  // 环境光源

                light.position.set(100, 100, 200);

                scene.add(light);

                light = new THREE.PointLight(0x00FF00);  // 点光源

                light.position.set(0, 0,300);

                scene.add(light);

            }

            var cube;

            function initObject() {

                var geometry = new THREE.CylinderGeometry( 70,100,200);  // 创建几何体  宽度  长度  深度

                var material = new THREE.MeshLambertMaterial( { color:0xFFFFFF} );  // 创建外表和设置颜色

                var mesh = new THREE.Mesh( geometry,material);  // Mesh是一个类，用来生成物体

                mesh.position = new THREE.Vector3(0,0,0);

                scene.add(mesh);  // 加到场景

            }

            function threeStart() {

                initThree();

                initCamera();

                initScene();

                initLight();

                initObject();

                animation();

            }

            function animation()

            {

                changeFov();

                renderer.render(scene, camera);

                requestAnimationFrame(animation);  // 循环调用

            }

            function setCameraFov(fov)

            {

                camera.fov = fov;

                camera.updateProjectionMatrix();

            }

            function changeFov()

            {

                var txtFov = document.getElementById("txtFov").value;

                var val = parseFloat(txtFov);

                setCameraFov(val);

            }

        </script>

    </head>

    <body onload="threeStart();">

        <div id="canvas-frame"></div>

        <div>

            Fov:<input type="text" value="45" id="txtFov"/>(0到180的值)

        </div>

    </body>

</html>

附带three.js代码，点击下载

上面代码是透视投影摄像机的效果，如下图所示：

three.js之正投影摄像机与透视投影摄像机的区别-LMLPHP

正投影摄像机

camera = new THREE.OrthographicCamera( window.innerWidth / - 2, window.innerWidth / 2, window.innerHeight / 2, window.innerHeight / - 2, 10, 1000 );

它基本上各个方向大小都相同，没有透视的效果。如下图所示：

three.js之正投影摄像机与透视投影摄像机的区别-LMLPHP