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Hello_Triangle.html
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87 lines (78 loc) · 2.97 KB
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Canvas</title>
<style>
#box {
background-color: pink;
}
#pic {
display: block;
margin: 0 auto;
}
</style>
</head>
<body>
<div id="box">
<canvas id="pic" width="500px" height="500px">
</div>
</body>
<script src="lib/cuon-matrix.js"></script>
<script src="lib/webgl-utils.js"></script>
<script src="lib/webgl-debug.js"></script>
<script src="lib/cuon-utils.js"></script>
<script>
window.onload = (function() {
/* var VSHADER_SOURCE ='void main(){gl_Position = vec4(0.0,0.0,0.0,1.0);gl_PointSize = 23.0;}';
var FSHADER_SOURCE ='void main(){gl_FragColor = vec4(1.0,0.0,0.0,1.0);}';*/
var VSHADER_SOURCE = `
attribute vec4 a_Position;
attribute float a_PointSize;
void main(){gl_Position = a_Position;}
`;
var FSHADER_SOURCE = `
precision mediump float;
uniform vec4 u_FragColor;
void main(){gl_FragColor = u_FragColor;}
`;
var canvas = document.getElementById("pic");
// ======================================================================
var gl = getWebGLContext(canvas);
//初始化着色器
initShaders(gl, VSHADER_SOURCE, FSHADER_SOURCE);
var a_Position = gl.getAttribLocation(gl.program, 'a_Position');
//var a_PointSize = gl.getAttribLocation(gl.program, 'a_PointSize');
var u_FragColor = gl.getUniformLocation(gl.program, 'u_FragColor');
var n = initVertexBuffers(gl);
//设置画布底色
gl.clearColor(0.0, 0.0, 0.0, 1.0);
//清除颜色缓冲区
gl.clear(gl.COLOR_BUFFER_BIT);
//gl.vertexAttrib1f(a_PointSize, 30.0);
gl.uniform4f(u_FragColor,0.3,0.8,0.1,1.0);
// gl.drawArrays(gl.POINTS,0,n);
// gl.drawArrays(gl.LINES,0,n);
// gl.drawArrays(gl.LINE_LOOP,0,n);
// gl.drawArrays(gl.LINE_STRIP,0,n);
// gl.drawArrays(gl.TRIANGLES,0,n);
// gl.drawArrays(gl.TRIANGLE_STRIP,0,n);
gl.drawArrays(gl.TRIANGLE_FAN,0,n);
function initVertexBuffers(gl){
var vertices = new Float32Array([0.0,0.5,-0.5,-0.5,0.5,-0.5,0.5,0.8]);
var n = 4;
//创建了缓冲区对象
var vertexBuffer = gl.createBuffer();
//将缓冲区对象绑定到目标
gl.bindBuffer(gl.ARRAY_BUFFER,vertexBuffer);
//向缓冲区对象写入数据
gl.bufferData(gl.ARRAY_BUFFER,vertices,gl.STATIC_DRAW);
//将缓冲区对象分配给a_Position变量
gl.vertexAttribPointer(a_Position,2,gl.FLOAT,false,0,0);
//连接a_Position变量与分配给它的缓冲区对象
gl.enableVertexAttribArray(a_Position);
return n;
}
});
</script>
</html>