
/*
** 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;

// Function declarations.
float function(inout float par[3]);
bool is_all(const in float array[3], const in float value);
void set_all(out float array[3], const in float value);

void main (void)
{
	float par[3];
	float ret = 0.0;

	float gray = 0.0;

	// Initialize the entire array to 1.0.
	set_all(par, 1.0);

	ret = function(par);

	// The parameter should be changed by the function and the function should return 1.0.
	if(is_all(par, 0.0) && (ret == 1.0))
	{
		gray = 1.0;
	}

	color = vec4(gray, gray, gray, 1.0);
	gl_Position = gtf_ModelViewProjectionMatrix * gtf_Vertex;
}

// Function definition.
float function(inout float par[3])
{
	// Return the value of the array.
	if(is_all(par, 1.0))
	{
		// Test parameter qualifier (default is "in").
		set_all(par, 0.0);

		return 1.0;
	}
	else
		return 0.0;
}

bool is_all(const in float array[3], const in float value)
{
	bool ret = true;

	if(array[0] != value)
		ret = false;
	if(array[1] != value)
		ret = false;
	if(array[2] != value)
		ret = false;

	return ret;
}

void set_all(out float array[3], const in float value)
{
	array[0] = value;
	array[1] = value;
	array[2] = value;
}
