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/*
Copyright (c) 2019 The Khronos Group Inc.
Use of this source code is governed by an MIT-style license that can be
found in the LICENSE.txt file.
*/
#ifdef GL_ES
precision mediump float;
#endif
varying vec4 color;
void main (void)
{
const float M_PI = 3.14159265358979323846;
float c = 0.5 * M_PI * 2.0 * (color.r - 0.5);
float o;
if(abs(c) < 0.5) // -45..45
o = 0.5 * (sin(c) / cos(c)) + 0.5;
else // 45..90, -45..-90
o = 0.5 * (cos(c) / sin(c)) + 0.5;
gl_FragColor = vec4(o, 0.0, 0.0, 1.0);
}
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