
/*
** 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_Vertex;
uniform mat4 gtf_ModelViewProjectionMatrix;
varying vec4 color;

#define ERROR_EPSILON 0.1

void main (void)
{
	vec4 L1 = vec4(1.0, 2.0, 3.0, 4.0);
	vec4 L2 = vec4(5.0, 6.0, 7.0, 8.0);
	vec4 L3 = vec4(9.0, 10.0, 11.0, 12.0);
	vec4 L4 = vec4(13.0, 14.0, 15.0, 16.0);

	mat4 a = mat4(L1,L2,L3,L4);

	float gray,sum1=0.0,sum2=0.0,sum3=0.0,sum4=0.0;
	int i;

	sum1 = sum1 + a[0][0];
	sum2 = sum2 + a[1][0];
	sum3 = sum3 + a[2][0];
	sum4 = sum4 + a[3][0];
	
	sum1 = sum1 + a[0][1];
	sum2 = sum2 + a[1][1];
	sum3 = sum3 + a[2][1];
	sum4 = sum4 + a[3][1];
	
	sum1 = sum1 + a[0][2];
	sum2 = sum2 + a[1][2];
	sum3 = sum3 + a[2][2];
	sum4 = sum4 + a[3][2];
	
	sum1 = sum1 + a[0][3];
	sum2 = sum2 + a[1][3];
	sum3 = sum3 + a[2][3];
	sum4 = sum4 + a[3][3];

	if( ( sum1 > 10.0-ERROR_EPSILON && sum1 < 10.0+ERROR_EPSILON  ) && 
		( sum2 > 26.0-ERROR_EPSILON && sum2 < 26.0+ERROR_EPSILON) && 
		( sum3 > 42.0-ERROR_EPSILON && sum3 < 42.0+ERROR_EPSILON) && 
		( sum4 > 58.0-ERROR_EPSILON && sum4 < 58.0+ERROR_EPSILON) )
	gray=1.0;
	else gray=0.0;
	color = vec4(gray, gray, gray, 1.0);
	gl_Position = gtf_ModelViewProjectionMatrix * gtf_Vertex;
}

