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<!DOCTYPE html>
<head>
<meta charset="utf-8"/>
<title>GLSL пеперуда</title>
<script src="webgl-fmi.js"></script>
<script id="vshader" type="x-shader/x-vertex">
#define PI 3.1415926538
#define ASPECT_RATIO 1.5
attribute float aPoint;
attribute float aPointCnt;
attribute vec3 aRGB;
varying vec3 vRGB;
void main ()
{
float alpha = aPoint * (360.0 / aPointCnt) * (PI / 180.0);
float mag = (exp(cos(alpha)) - 2.0 * cos(4.0 * alpha) + pow(sin(alpha / 15.0), 5.0)) / 2.475;
gl_Position = vec4(mag * sin(alpha) / ASPECT_RATIO, mag * cos(alpha) - 0.268, 0, 1);
gl_PointSize = 4.0;
vRGB = aRGB;
}
</script>
<script id="fshader" type="x-shader/x-fragment">
precision mediump float;
varying vec3 vRGB;
void main( )
{
gl_FragColor = vec4(vRGB,1);
}
</script>
<script>
function start( )
{
gl = getContext("picasso");
glprog = getProgram("vshader","fshader");
aPoint = gl.getAttribLocation(glprog, "aPoint");
aPointCnt = gl.getAttribLocation(glprog, "aPointCnt");
aRGB = gl.getAttribLocation(glprog,"aRGB");
gl.clearColor(1,1,1,1);
gl.clear(gl.COLOR_BUFFER_BIT);
var n = 250;
var data = [ ];
for(var i=0; i<n; i++) data.push(i);
var buf = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER,buf);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(data), gl.STATIC_DRAW);
gl.vertexAttrib3f(aRGB,1,0.2,0);
gl.vertexAttribPointer(aPoint, 1, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(aPoint);
gl.vertexAttrib1f(aPointCnt, n);
gl.drawArrays(gl.LINE_LOOP,0,n);
}
</script>
</head>
<body onload="start()">
<h2>GLSL пеперуда</h2>
<noscript>
Искаме JavaScript, но няма!
</noscript>
<canvas id="picasso" width="600" height="400" style="border: solid;">
Искаме canvas, но няма!
</canvas>
</body>
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