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<!DOCTYPE html>
<head>
<meta charset="utf-8"/>
<title>Септагон</title>
<script src="webgl-fmi.js"></script>
<script id="vshader" type="x-shader/x-vertex">
attribute vec2 aXY;
void main ()
{
gl_Position = vec4(aXY,0,1);
gl_PointSize = 10.0;
}
</script>
<script id="fshader" type="x-shader/x-fragment">
void main( )
{
gl_FragColor = vec4(0,0,0,1);
}
</script>
<script>
function start( )
{
gl = getContext("picasso");
glprog = getProgram("vshader","fshader");
aXY = gl.getAttribLocation(glprog,"aXY");
gl.clearColor(1,1,1,1);
gl.clear(gl.COLOR_BUFFER_BIT);
var data = [ ]; // В този масив трябва да са 7-те точки
const aspectRatio = 600 / 400;
const n = 7;
const r = 0.8;
for (var i = 1; i <= n; i++)
data.push(Math.sin(2.0 * Math.PI * i / n) * r / aspectRatio, Math.cos(2.0 * Math.PI * i / n) * r);
var buf = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buf);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(data), gl.STATIC_DRAW);
gl.vertexAttribPointer(aXY, 2, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(aXY);
gl.drawArrays(gl.POINTS, 0, n);
}
</script>
</head>
<body onload="start()">
<h2>Септагон</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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