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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" >
<title>Rotating Square</title>

<script id="vertex-shader" type="x-shader/x-vertex">
attribute vec4 vPosition;
uniform float theta;

void
main()
{
    float s = 0.3*sin( theta );
    float c = 0.4 * cos( theta );

    gl_Position.x = -s * vPosition.y + c * vPosition.x + 0.4*sin(theta);
    gl_Position.y =  s * vPosition.x + c * vPosition.y + 0.4*cos(theta);
    gl_Position.z = 0.0;
    gl_Position.w = 1.0;
}
</script>

<script id="fragment-shader" type="x-shader/x-fragment">

precision mediump float;

void
main()
{

    float rateX = 3.0;
    float rateY = 5.0;
    float sinScaleX = 10.0;
    float sinScaleY = 300.0;

    float lerpValue = gl_FragCoord.y / 500.0;
    lerpValue = cos(lerpValue*sinScaleY);
    if (lerpValue>0.3) lerpValue = 0.5*lerpValue;

    float lerpValue2 = gl_FragCoord.x / 500.0;
    lerpValue2 = sin(lerpValue2*sinScaleX);
    if (lerpValue2>.7) lerpValue2 = 0.5*lerpValue2;

    gl_FragColor = rateY * mix(vec4(12/255, 53/255, 169/255, 1.0), vec4(0.3, 0.3, 0.0, 1.0), lerpValue)
        + rateX * mix(vec4(1.5, 0.2, 0.3, 1.0), vec4(0.4, 0.4, 0.2, 1.0), lerpValue2);
}
</script>

<script type="text/javascript" src="../Common/webgl-utils.js"></script>
<script type="text/javascript" src="../Common/initShaders.js"></script>
<script type="text/javascript" src="../Common/MV.js"></script>
<script type="text/javascript" src="rotatingSquare1.js"></script>
</head>

<body>
<canvas id="gl-canvas" width="1024" height="1024">
Oops ... your browser doesn't support the HTML5 canvas element
</canvas>
</body>
</html>