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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.
*/
attribute vec4 gtf_Vertex;
attribute vec4 gtf_Color;
uniform mat4 gtf_ModelViewProjectionMatrix;
varying vec4 color;
void main (void)
{
const float M_PI = 3.14159265358979323846;
vec2 x = 2.0 * (gtf_Color.gg - 0.5);
vec2 y = 2.0 * (gtf_Color.bb - 0.5);
const float epsilon = 1.0e-4;
color = vec4(0.0, 0.0, 0.0, 1.0);
// Avoid evaluating atan(0, x) for x < epsilon because it's implementation-dependent
if(x[0] > epsilon || abs(y[0]) > epsilon)
{
color[0] = atan(y[0], x[0]) / (2.0 * M_PI) + 0.5;
}
if(x[1] > epsilon || abs(y[1]) > epsilon)
{
color[1] = atan(y[1], x[1]) / (2.0 * M_PI) + 0.5;
}
gl_Position = gtf_ModelViewProjectionMatrix * gtf_Vertex;
}
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