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Introduction to Three.js hello world and how to draw lines

巴扎黑Original: 2017-09-26 09:39:191457browse

This article mainly introduces you to the relevant information about hello world for getting started with Three.js and how to draw lines. The article introduces it in great detail through sample code. It has certain reference learning value for everyone's study or work. It needs Friends, please follow the editor to learn together.

Preface

This article is an introductory tutorial for learning Three.js. It introduces the implementation of hello world and lines through examples. The following is not Enough said, let’s take a look at the detailed introduction.

hello world

First of all, we use three.js to create a cube hello world type case.

<!doctype html> 
<html> 
<head> 
 <meta charset="UTF-8"> 
 <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"> 
 <meta http-equiv="X-UA-Compatible" content="ie=edge"> 
 <title>Document</title> 
 <script src="build/three.js"></script> 
 <style> 
  body{margin:0;} 
  canvas{width: 100%; height:100%; display: block;} 
 </style> 
</head> 
<body> 
<script> 
 //创建场景 
 var scene = new THREE.Scene(); 
 //设置相机（视野，显示口的宽高比，近裁剪面，远裁剪面） 
 var camera = new THREE.PerspectiveCamera( 75, window.innerWidth/window.innerHeight, 0.1, 1000 ); 
 //渲染器 
 var renderer = new THREE.WebGLRenderer(); 
 //设置渲染器的高度和宽度，如果加上第三个值 false，则按场景大小显示，等比例缩放 
 renderer.setSize( window.innerWidth, window.innerHeight,false); 
 //将渲染器添加到html当中 
 document.body.appendChild( renderer.domElement ); 
 
 //盒子模型（BoxGeometry），这是一个包含立方体所有顶点和填充面的对象。 
 var geometry = new THREE.BoxGeometry( 1, 2, 1 ); 
 //使用网孔基础材料（MeshBasicMaterial）进行着色器，这里只绘制了一个绿色 
 var material = new THREE.MeshBasicMaterial( { color: 0x00ffff } ); 
 //使用网孔(Mesh)来承载几何模型 
 var cube = new THREE.Mesh( geometry, material ); 
 //将模型添加到场景当中 
 scene.add( cube ); 
 //将相机沿z轴偏移5 
 camera.position.z = 5; 
 
 //设置一个动画函数 
 var animate = function () { 
  //一秒钟调用60次，也就是以每秒60帧的频率来绘制场景。 
  requestAnimationFrame( animate ); 
 
  //console.log(cube.rotation); 
  //每次调用模型的沿xy轴旋转0.01 
  cube.rotation.x += 0.01; 
  cube.rotation.y += 0.01; 
  //使用渲染器把场景和相机都渲染出来 
  renderer.render(scene, camera); 
 }; 
 
 animate(); 
</script> 
</body> 
</html>

Analysis of the above code case:

(1) First introduce the three.js library file, Just like introducing jq.

(2) Create scene (line 17)

(3) Create camera and set field of view, display aspect ratio, near clipping plane, far clipping plane (Line 19)

(4) Create a renderer, set attributes, and place it in the dom (Lines 21-25)

(5) Create a cube model , and put it into the scene (28-34)

(6) Set the camera position (line 36)

(7) Set an animation function and use The renderer renders the scene and camera at 60 frames per second, displays it, and turns it into an animation.

Use Three.js to draw lines

The above is the effect displayed after the drawing is completed.

<!doctype html> 
<html> 
<head> 
 <meta charset="UTF-8"> 
 <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"> 
 <meta http-equiv="X-UA-Compatible" content="ie=edge"> 
 <title>Document</title> 
 <script src="build/three.js"></script> 
 <style> 
  body{margin:0;} 
  canvas{width: 100%; height:100%; display: block;} 
 </style> 
</head> 
<body> 
<script> 
 //创建场景 
 var scene = new THREE.Scene(); 
 //设置相机（视野，显示口的宽高比，近裁剪面，远裁剪面） 
 var camera = new THREE.PerspectiveCamera( 75, window.innerWidth/window.innerHeight, 0.1, 1000 ); 
 //设置相机的视点 
 camera.position.set(0,0,100); 
 //设置相机的朝向 
 camera.lookAt(new THREE.Vector3(0,0,0)); 
 //渲染器 
 var renderer = new THREE.WebGLRenderer(); 
 //设置渲染器的高度和宽度，如果加上第三个值 false，则按场景大小显示，等比例缩放 
 renderer.setSize( window.innerWidth, window.innerHeight,false); 
 //将渲染器添加到html当中 
 document.body.appendChild( renderer.domElement ); 
 
 //定义线的基本材料，我们可以使用LineBasicMaterial（实线材料）和LineDashedMaterial（虚线材料） 
 var material = new THREE.LineBasicMaterial({color:0x0000ff}); 
 //设置具有几何顶点的几何（Geometry）或缓冲区几何（BufferGeometry）设置顶点位置，看名字就知道了，一个是直接将数据保存在js里面的，另一个是保存在WebGL缓冲区内的，而且肯定保存到WebGL缓冲区内的效率更高 
 var geometry = new THREE.Geometry(); 
 geometry.vertices.push(new THREE.Vector3(-10,0,0)); 
 geometry.vertices.push(new THREE.Vector3(0,10,0)); 
 geometry.vertices.push(new THREE.Vector3(10,0,0)); 
 //使用Line方法将线初始化 
 var line = new THREE.Line(geometry, material); 
 //将线添加到场景 
 scene.add(line); 
 
 //使用渲染器渲染出场景和相机 
 renderer.render(scene, camera); 
</script> 
</body> 
</html>

Compared with the previous section, there is only a difference in the model. Here, we first use the line texture method to set the line texture, and then use geometric objects or buffers. The geometric object generates vertex coordinates, and finally calls the Line method to draw the line.

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