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<!DOCTYPE html>
<head>
<meta charset="utf-8"/>
<title>Филмова ролка</title>
<script src="webgl-fmi.js"></script>
<script id="vshader" type="x-shader/x-vertex">
attribute vec2 aXY;
void main ()
{
// аспекта поправяме с покомпонентно умножение
gl_Position = vec4(aXY*vec2(1.0/1.5,1),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");
aXY = gl.getAttribLocation(glprog,"aXY");
uColor = gl.getUniformLocation(glprog,"uColor");
gl.clearColor(1,1,1,1);
gl.clear(gl.COLOR_BUFFER_BIT);
// точки по ролката
var n = 360;
// създаване на окръжности
var data = [ ];
for(var i=0; i<n; i++)
data.push(Math.cos(2.0*Math.PI*i/n),Math.sin(2.0*Math.PI*i/n));
const innerCircleR = 0.14;
for (var i = 0; i < n; i++)
data.push(Math.cos(2 * Math.PI * i / n) * innerCircleR, Math.sin(2 * Math.PI * i / n) * innerCircleR);
const holes = 6;
const innerR = 0.25;
const outerR = 0.85;
const spacingDegr = 22;
var degrStep = n / holes;
for (var hole = 0; hole < holes; hole++) {
var maxDegr = (hole + 1) * degrStep - spacingDegr;
for (var i = hole * degrStep; i < maxDegr; i++)
data.push(Math.cos(2 * Math.PI * i / n) * outerR, Math.sin(2 * Math.PI * i / n) * outerR);
for (var i = maxDegr; i > hole * degrStep; i--)
data.push(Math.cos(2 * Math.PI * i / n) * innerR, Math.sin(2 * Math.PI * i / n) * innerR);
}
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(aXY);
gl.vertexAttribPointer(aXY,2,gl.FLOAT,false,0,0);
gl.drawArrays(gl.LINE_LOOP,0,n);
gl.drawArrays(gl.LINE_LOOP, n, n);
for (var i = 0; i < holes; i++)
gl.drawArrays(gl.LINE_LOOP, 2 * n + i * (degrStep - spacingDegr) * 2, (degrStep - spacingDegr) * 2);
}
</script>
</head>
<body onload="start()">
<h2>Филмова ролка</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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