webGL简单例子(klayge)
当前的WebGL版本是1.0,其实际上是个OpenGL ES 2.0的Javascript绑定,也就是可以用Javascript来调用OpenGL ES 2.0的函数,在网页中实现3D渲染。WebGL是桌面、移动、嵌入式平台通吃,只要支持OpenGL ES 2.0的平台就可以用WebGL。使用了WebGL的Web游戏等程序可以做到和本地桌面程序一样的绚烂。
目前支持WebGL的浏览器有Firefox 4.0 Beta、Chrome 9.0、Opera预览版、Safari每日构建版,NV和AMD的驱动都已经支持桌面的OpenGL ES 2.0,所以也就等于支持了WebGL。
这个例子主要是用于测试不同浏览器对WebGL的支持情况,它来自于这里:http://www.klayge.org/html/webgl_test.html 通过这个例子可以了解一个最简单的WebGL程序是如何写成的!另外,可通过这个网页WebGLReport来查看浏览器对WebGL的支持情况。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 | <html> <head> <title>WebGL test</title> <meta http-equiv= "content-type" content= "text/html; charset=ISO-8859-1" > <script id= "shader-vs" type= "x-shader/x-vertex" > attribute vec3 position; uniform mat4 mv; uniform mat4 proj; void main() { gl_Position = proj * mv * vec4(position, 1.0); } </script> <script id= "shader-fs" type= "x-shader/x-fragment" > void main() { gl_FragColor = vec4(0.8, 0.8, 0.0, 1.0); } </script> <script type= "text/javascript" > // Initialises WebGL and creates the 3D scene. function loadScene() { var canvas = document.getElementById( "webGLCanvas" ); if (!canvas.getContext) { alert( "There's no canvas available." ); return ; } var gl = canvas.getContext( "experimental-webgl" ); if (!gl) { alert( "There's no WebGL context available." ); return ; } var vendor_info = document.getElementById( "vendor_info" ); var renderer_info = document.getElementById( "renderer_info" ); var version_info = document.getElementById( "version_info" ); var ext_info = document.getElementById( "ext_info" ); vendor_info.innerHTML = gl.getParameter(gl.VENDOR); renderer_info.innerHTML = gl.getParameter(gl.RENDERER); version_info.innerHTML = gl.getParameter(gl.VERSION); var exts = gl.getSupportedExtensions(); var s = "" ; for (index in exts) { s += exts[index] + "<br />" ; } ext_info.innerHTML = s; gl.viewport(0, 0, canvas.width, canvas.height); var vertexShaderScript = document.getElementById( "shader-vs" ); var vertexShader = gl.createShader(gl.VERTEX_SHADER); gl.shaderSource(vertexShader, vertexShaderScript.text); gl.compileShader(vertexShader); if (!gl.getShaderParameter(vertexShader, gl.COMPILE_STATUS)) { alert( "Unable to compile the vertex shader" ); gl.deleteShader(vertexShader); return ; } var fragmentShaderScript = document.getElementById( "shader-fs" ); var fragmentShader = gl.createShader(gl.FRAGMENT_SHADER); gl.shaderSource(fragmentShader, fragmentShaderScript.text); gl.compileShader(fragmentShader); if (!gl.getShaderParameter(fragmentShader, gl.COMPILE_STATUS)) { alert( "Unable to compile the fragment shader" ); gl.deleteShader(fragmentShader); return ; } gl.program = gl.createProgram(); gl.attachShader(gl.program, vertexShader); gl.attachShader(gl.program, fragmentShader); gl.linkProgram(gl.program); if (!gl.getProgramParameter(gl.program, gl.LINK_STATUS)) { alert( "Unable to link shaders" ); gl.deleteProgram(gl.program); gl.deleteProgram(vertexShader); gl.deleteProgram(fragmentShader); return ; } gl.clearColor(0.2, 0.4, 0.6, 1.0); gl.clearDepth(1.0); gl.enable(gl.DEPTH_TEST); gl.depthFunc(gl.LEQUAL); var vertexBuffer = gl.createBuffer(); gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer); var vertices = new Float32Array([ 0.0, 1.0, 1.0, -1.0, -1.0, 1.0, 1.0, -1.0, 1.0 ]); gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW); gl.useProgram(gl.program); var vertexPosition = gl.getAttribLocation(gl.program, "position" ); gl.enableVertexAttribArray(vertexPosition); gl.vertexAttribPointer(vertexPosition, 3, gl.FLOAT, false , 0, 0); gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); var fov = 90.0; var aspect = canvas.width / canvas.height; var nearPlane = 1.0; var farPlane = 100.0; var top = nearPlane * Math.tan(fov / 2 * Math.PI / 180); var bottom = -top; var right = top * aspect; var left = -right; var a = (right + left) / (right - left); var b = (top + bottom) / (top - bottom); var c = (farPlane + nearPlane) / (farPlane - nearPlane); var d = (2 * farPlane * nearPlane) / (farPlane - nearPlane); var x = (2 * nearPlane) / (right - left); var y = (2 * nearPlane) / (top - bottom); var perspectiveMatrix = new Float32Array([ x, 0, a, 0, 0, y, b, 0, 0, 0, c, d, 0, 0, -1, 0 ]); var modelViewMatrix = new Float32Array([ 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1 ]); gl.uniformMatrix4fv(gl.getUniformLocation(gl.program, "proj" ), false , perspectiveMatrix); gl.uniformMatrix4fv(gl.getUniformLocation(gl.program, "mv" ), false , modelViewMatrix); gl.drawArrays(gl.TRIANGLES, 0, vertices.length / 3); } </script> </head> <body onload= "loadScene()" > <h1>WebGL Test</h1> <h3>Vendor</h3> <p id= "vendor_info" ></p> <h3>Renderer</h3> <p id= "renderer_info" ></p> <h3>Version</h3> <p id= "version_info" ></p> <h3>Extensions</h3> <p id= "ext_info" ></p> <h3>Rendering</h3> <canvas id= "webGLCanvas" width= "640" height= "480" ></canvas> <script type= "text/javascript" > var _gaq = _gaq || []; _gaq.push([ '_setAccount' , 'UA-16460301-1' ]); _gaq.push([ '_trackPageview' ]); ( function () { var ga = document.createElement( 'script' ); ga.type = 'text/javascript' ; ga.async = true ; ga.src = ( 'https:' == document.location.protocol ? 'https://ssl' : 'http://www' ) + '.google-analytics.com/ga.js' ; var s = document.getElementsByTagName( 'script' )[0]; s.parentNode.insertBefore(ga, s); })(); </script> </body> </html> |
分类:
编程实践
标签:
JavaScript
, WebGL
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