本文通过WebGL例子,来帮助WebGL入门学习。
一、概述
WebGL (Web Graphics Library)是一组基于Open ES、在Web内渲染3D图形的Javascript APIs。
Ref. from Khronos Group: WebGL
WebGL™ is a cross-platform, royalty-free open web standard for a low-level 3D graphics API based on OpenGL ES, exposed to ECMAScript via the HTML5 Canvas element.
二、配置WebGL开发环境
三、例子1:绘制三角形
<!DOCTYPE HTML>
<html lang="en">
<head>
<title>Draw a triangle</title>
<meta charset="utf-8">
<script type="text/javascript">
var gl;
var canvas;
var shaderProgram;
var vertexBuffer;
function createGLContext(canvas)
{
var names = ["webgl", "experimental-webgl"];
var context = null;
for(var i = 0; i < names.length; i++)
{
try
{
context = canvas.getContext(names[i]);
}
catch(e)
{
if (context)
{
break;
}
}
}
if(context)
{
context.viewportWidth = canvas.width;
context.viewportHeight = canvas.height;
}
else
{
alert("Failed to create WebGL context!");
}
return context;
}
function loadShader(type, shaderSource)
{
var shader = gl.createShader(type);
gl.shaderSource(shader, shaderSource);
gl.compileShader(shader);
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS))
{
alert("Error compiling shader" + gl.getShaderInfoLog(shader));
gl.deleteShader(shader);
return null
}
return shader;
}
function setupShaders()
{
var vertexShaderSource =
"attribute vec3 aVertexPosition; \n" +
"void main() \n" +
"{ \n" +
" gl_Position = vec4(aVertexPosition, 1.0); \n" +
"} \n";
var fragmentShaderSource =
"precision mediump float; \n" +
"void main() \n" +
"{ \n" +
" gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0); \n" +
"} \n";
var vertexShader = loadShader(gl.VERTEX_SHADER, vertexShaderSource);
var fragmentShader = loadShader(gl.FRAGMENT_SHADER, fragmentShaderSource);
shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram(shaderProgram);
if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS))
{
alert("Failed to setup shaders!");
}
gl.useProgram(shaderProgram);
shaderProgram.vertexPositionAttribute =
gl.getAttribLocation(shaderProgram, "aVertexPosition");
}
function setupBuffers()
{
vertexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
var triangleVertices = [
0.0, 0.5, 0.0,
-0.5, -0.5, 0.0,
0.5, -0.5, 0.0
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(triangleVertices), gl.STATIC_DRAW);
vertexBuffer.itemSize = 3;
vertexBuffer.numberOfItems = 3;
}
function draw()
{
gl.viewport(0,0, gl.viewportWidth, gl.viewportHeight);
gl.clear(gl.COLOR_BUFFER_BIT);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, vertexBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute);
gl.drawArrays(gl.TRIANGLES, 0, vertexBuffer.numberOfItems);
}
function startup()
{
canvas = document.getElementById("myGLCanvas");
gl = createGLContext(canvas);
setupShaders();
setupBuffers();
gl.clearColor(0.0,0.0,0.0,1.0);
draw();
}
</script>
</head>
<body onload="startup();">
<canvas id="myGLCanvas" width="500" height="500"></canvas>
</body>
</html>
参考资料
Andreas Anyuru. Professional WebGL Programming: Developing 3D Graphics for the Web.
Kouichi Matsuda, Rodger Lea. WebGL Programming Guide: Interactive 3D Graphics Programming with WebGL.
网络资料
WebGLhttps://www.khronos.org/webgl/
WebGL 2.0 Specificationhttps://registry.khronos.org/webgl/specs/latest/2.0/
Three.jshttps://threejs.org/文章来源:https://www.toymoban.com/news/detail-636004.html
BabylonJShttps://www.babylonjs.com/文章来源地址https://www.toymoban.com/news/detail-636004.html
到了这里,关于WebGL: 几个入门小例子的文章就介绍完了。如果您还想了解更多内容,请在右上角搜索TOY模板网以前的文章或继续浏览下面的相关文章,希望大家以后多多支持TOY模板网!