
/*
** Copyright (c) 2012 The Khronos Group Inc.
**
** Permission is hereby granted, free of charge, to any person obtaining a
** copy of this software and/or associated documentation files (the
** "Materials"), to deal in the Materials without restriction, including
** without limitation the rights to use, copy, modify, merge, publish,
** distribute, sublicense, and/or sell copies of the Materials, and to
** permit persons to whom the Materials are furnished to do so, subject to
** the following conditions:
**
** The above copyright notice and this permission notice shall be included
** in all copies or substantial portions of the Materials.
**
** THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
** IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
** CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
** MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.
*/


attribute vec4 gtf_Color;
attribute vec4 gtf_Vertex;
uniform mat4 gtf_ModelViewProjectionMatrix;
varying vec4 color;

void main (void)
{
	const float M_PI = 3.14159265358979323846;

	// Both are unit vectors
	vec2 v1;
	vec2 v2 = normalize(vec2(1.0, 1.0));

	float theta = gtf_Color.g * 2.0 * M_PI;
	float phi = gtf_Color.b * 2.0 * M_PI;
	v1.x = cos(theta) * sin(phi);
	v1.y = sin(theta) * sin(phi);

	vec2 result;
	float eta = 0.5;
	float k = 1.0 - eta * eta * (1.0 - dot(v1, v2) * dot(v1, v2));
	if(k < 0.0)
		result = vec2(0.0);
	else
		result = eta * v1 - (eta * dot(v1, v2) + sqrt(k)) * v2;

	color = vec4((result + 1.0) / 2.0, 0.0, 1.0);
	gl_Position = gtf_ModelViewProjectionMatrix * gtf_Vertex;
}
