Chapter 1:Create You First 3D Scene With Three.js

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1,各浏览器对WebGL的支持

手机浏览器对WebGL的支持:

书的源码:https://github.com/josdirksen/learning-threejs

第一次用浏览器打开代码可能无法正常显示,好像要对浏览器做一些设置额。

创建第一个3D场景包括这几样东西:

<!DOCTYPE html>

<html>

<head>
    <title>Example 01.06 - Screen size change</title>
    <script type="text/javascript" src="../libs/three.js"></script>
    <script type="text/javascript" src="../libs/stats.js"></script>//shows the frames per second(fps) for animation
    <script type="text/javascript" src="../libs/dat.gui.js"></script>//allows you to very easily create a simple user interface component that can change variables in your code
    <style>
        body {
            /* set margin to 0 and overflow to hidden, to go fullscreen */
            margin: 0;
            overflow: hidden;
        }
    </style>
</head>
<body>

<div id="Stats-output">
</div>
<!-- Div which will hold the Output -->
<div id="WebGL-output">
</div>

<!-- Javascript code that runs our Three.js examples -->
<script type="text/javascript">

    var camera;
    var scene;
    var renderer;

    // once everything is loaded, we run our Three.js stuff.
    function init() {
    
        var stats = initStats();

        // create a scene, that will hold all our elements such as objects, cameras and lights.
        scene = new THREE.Scene();

        // create a camera, which defines where we\'re looking at. 第一个参数是摄像机的角度,其他因素不变的情况下角度越大,看到的场景越小,第二个是场景的比例,第三个是near,第四个是far我们能看到的是near和far之间的内容
        camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);

        // create a render and set the size
        renderer = new THREE.WebGLRenderer();

        renderer.setClearColor(new THREE.Color(0xEEEEEE, 1.0));
        renderer.setSize(window.innerWidth, window.innerHeight);
        renderer.shadowMapEnabled = true;//默认是不开启阴影效果的,如果要显示阴影在这里要把它设为true;

        // create the ground plane
        var planeGeometry = new THREE.PlaneGeometry(60, 20, 1, 1);//创建一个长为60,宽为20的长方形,后面那两个参数是可选的,分别为widthsegements,heightsegements
        var planeMaterial = new THREE.MeshLambertMaterial({color: 0xffffff});//设置材质,并初始化材质颜色
        var plane = new THREE.Mesh(planeGeometry, planeMaterial); //把二者合并为一个mesh对象
        plane.receiveShadow = true;//接收阴影

        // rotate and position the plane
        plane.rotation.x = -0.5 * Math.PI;
        plane.position.x = 15;
        plane.position.y = 0;
        plane.position.z = 0;

        // add the plane to the scene
        scene.add(plane);

        // create a cube
        var cubeGeometry = new THREE.BoxGeometry(4, 4, 4);//新建一个立方体,参数为width,height,depth,后面还有三个可选参数,分别为widthsegments,heightsegments,depthsegments
        var cubeMaterial = new THREE.MeshLambertMaterial({color: 0xff0000});
        var cube = new THREE.Mesh(cubeGeometry, cubeMaterial);
        cube.castShadow = true;

        // position the cube
        cube.position.x = -4;
        cube.position.y = 3;
        cube.position.z = 0;

        // add the cube to the scene
        scene.add(cube);

        var sphereGeometry = new THREE.SphereGeometry(4, 20, 20);//SphereGeometry(radiuswidthSegmentsheightSegmentsphiStartphiLengththetaStartthetaLength)
var sphereMaterial = new THREE.MeshLambertMaterial({color: 0x7777ff});
        var sphere = new THREE.Mesh(sphereGeometry, sphereMaterial);

        // position the sphere
        sphere.position.x = 20;
        sphere.position.y = 0;
        sphere.position.z = 2;
        sphere.castShadow = true;

        // add the sphere to the scene
        scene.add(sphere);

        // position and point the camera to the center of the scene
        camera.position.x = -30;
        camera.position.y = 40;
        camera.position.z = 30;
        camera.lookAt(scene.position);

        // add subtle ambient lighting
        var ambientLight = new THREE.AmbientLight(0x0c0c0c);
        scene.add(ambientLight);

        // add spotlight for the shadows
        var spotLight = new THREE.SpotLight(0xffffff);
        spotLight.position.set(-40, 60, -10);
        spotLight.castShadow = true;
        scene.add(spotLight);

        // add the output of the renderer to the html element
        document.getElementById("WebGL-output").appendChild(renderer.domElement);

        // call the render function
        var step = 0;

        var controls = new function () {
            this.rotationSpeed = 0.02;
            this.bouncingSpeed = 0.03;
        };

        var gui = new dat.GUI();
        gui.add(controls, \'rotationSpeed\', 0, 0.5);
        gui.add(controls, \'bouncingSpeed\', 0, 0.5);

        render();

        function render() {
            stats.update();
            // rotate the cube around its axes
            cube.rotation.x += controls.rotationSpeed;
            cube.rotation.y += controls.rotationSpeed;
            cube.rotation.z += controls.rotationSpeed;

            // bounce the sphere up and down
            step += controls.bouncingSpeed;
            sphere.position.x = 20 + ( 10 * (Math.cos(step)));
            sphere.position.y = 2 + ( 10 * Math.abs(Math.sin(step)));

            // render using requestAnimationFrame
            requestAnimationFrame(render);
            renderer.render(scene, camera);
        }

        function initStats() {

            var stats = new Stats();

            stats.setMode(0); // 0: fps, 1: ms

            // Align top-left
            stats.domElement.style.position = \'absolute\';
            stats.domElement.style.left = \'0px\';
            stats.domElement.style.top = \'0px\';

            document.getElementById("Stats-output").appendChild(stats.domElement);

            return stats;
        }
    }
    function onResize() {
        camera.aspect = window.innerWidth / window.innerHeight;
        camera.updateProjectionMatrix();
        renderer.setSize(window.innerWidth, window.innerHeight);
    }


    window.onload = init;

    // listen to the resize events
    window.addEventListener(\'resize\', onResize, false);

</script>
</body>
</html>

 

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