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<!DOCTYPE html>
<head>
<meta charset="utf-8"/>
<title>Синус-косинус</title>
<script src="webgl-fmi.js"></script>
<script id="vshader" type="x-shader/x-vertex">
attribute vec2 aXY;
attribute vec3 aRGB;
varying vec3 vRGB;
void main ()
{
gl_Position = vec4(aXY,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");
aXY = gl.getAttribLocation(glprog,"aXY");
aRGB = gl.getAttribLocation(glprog,"aRGB");
gl.clearColor(1,1,1,1);
gl.clear(gl.COLOR_BUFFER_BIT);
// Общо n зъба
var n = 20;
var data = [];
// Axies
data.push( 0.9, 0, 0, 0, 0);
data.push(-0.9, 0, 0, 0, 0);
data.push( 0, 0.9, 0, 0, 0);
data.push( 0, -0.9, 0, 0, 0);
// Figure
const aspectRatio = 600 / 400;
const range = 3;
var step = 1.8 / n;
for (var x = -0.9; x < 0.899; x += step) {
data.push(x, Math.sin(x * range) / range, 1, 0, 0);
data.push(x, Math.cos(x * range) / range, 1, 0, 0);
var tx = x + step / 2;
data.push(tx, Math.cos(tx * range) / range, 1, 0, 0);
data.push(tx, Math.sin(tx * range) / range, 1, 0, 0);
}
var buf = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER,buf);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(data), gl.STATIC_DRAW);
gl.enableVertexAttribArray(aXY);
gl.enableVertexAttribArray(aRGB);
gl.vertexAttribPointer(aXY,2,gl.FLOAT,false, 5 * FLOATS, 0);
gl.vertexAttribPointer(aRGB, 3, gl.FLOAT, false, 5 * FLOATS, 2 * FLOATS);
gl.drawArrays(gl.LINES, 0, 4);
gl.drawArrays(gl.LINE_STRIP, 4, n * 4);
}
</script>
</head>
<body onload="start()">
<h2>Синус-косинус</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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