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<!DOCTYPE html>
<head>
<meta charset="utf-8"/>
<title>Зъбно колело</title>
<script src="webgl-fmi.js"></script>
<script id="vshader" type="x-shader/x-vertex">
// ъгъл по зъбното колело
attribute float aAngle;
attribute float aMin;
attribute float aMax;
attribute float aRadius;
attribute float aFluct;
#define TEETH 11.0
void main ()
{
// тук да се оправи да се рисуват елементите на
// зъбното колело - както зъбчатата част, така
// и кръглата и плътно кръглата
float r = aRadius + aFluct * clamp(sin(aAngle * TEETH), aMin, aMax);
gl_Position = vec4(r * cos(aAngle)/1.5, r * sin(aAngle),0,1);
}
</script>
<script id="fshader" type="x-shader/x-fragment">
precision mediump float;
uniform vec3 uColor;
void main( )
{
gl_FragColor = vec4(uColor,1);
}
</script>
<script>
function start( )
{
gl = getContext("picasso");
glprog = getProgram("vshader","fshader");
uColor = gl.getUniformLocation(glprog,"uColor");
aAngle = gl.getAttribLocation(glprog,"aAngle");
aMin = gl.getAttribLocation(glprog, "aMin");
aMax = gl.getAttribLocation(glprog, "aMax");
aRadius = gl.getAttribLocation(glprog, "aRadius");
aFluct = gl.getAttribLocation(glprog, "aFluct");
gl.clearColor(1,1,1,1);
gl.clear(gl.COLOR_BUFFER_BIT);
// точки по зъбното колело
var n = 500;
// n ъгъла от 0 до 2*pi
var data = [];
for(var i=0; i<n; i++) data.push(2*Math.PI*i/n);
var buf = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER,buf);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(data), gl.STATIC_DRAW);
gl.uniform3f(uColor,0.3,0.7,0.2);
gl.enableVertexAttribArray(aAngle);
gl.vertexAttribPointer(aAngle,1,gl.FLOAT,false,0,0);
gl.vertexAttrib1f(aRadius, 0.8);
gl.vertexAttrib1f(aFluct, 0.2);
gl.vertexAttrib1f(aMin, -0.5);
gl.vertexAttrib1f(aMax, 0.5);
gl.drawArrays(gl.LINE_LOOP,0,n);
gl.vertexAttrib1f(aRadius, 0.55);
gl.vertexAttrib1f(aFluct, 0.0);
gl.drawArrays(gl.LINE_LOOP,0,n);
gl.vertexAttrib1f(aRadius, 0.52);
gl.drawArrays(gl.LINE_LOOP,0,n);
var radius = 0.1;
var steps = 100;
for (var i = 0; i < 100; i++) {
gl.vertexAttrib1f(aRadius, radius * i / steps);
gl.drawArrays(gl.LINE_LOOP,0,n);
}
}
</script>
</head>
<body onload="start()">
<h2>Зъбно колело</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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