// Radial.h


#ifndef __Radial
#define __Radial

#include <windows.h>
#include <gl\glut.h>

void radInit (int texWidth, int texHeight, int winWidth, int winHeight);
void radUninit ();

void radBegin ();
void radEnd ();

void radDraw (int texRepeat, float texIncrement);

void _radViewOrtho ();
void _radViewPerspective ();

#endif

  

  
// Radial.cpp


#include "Radial.h"

unsigned int _radTexID = 0;

int _radTexWidth  = 0;
int _radTexHeight = 0;
int _radWinWidth  = 0;
int _radWinHeight = 0;

void radInit (int texWidth, int texHeight, int winWidth, int winHeight)
{
	unsigned int* texData;

	int texSize = (texWidth * texHeight) * 4 * sizeof (unsigned int);

	texData = new GLuint[texSize];

	ZeroMemory (texData, texSize);

	glGenTextures (1, &_radTexID);

	glBindTexture (GL_TEXTURE_2D, _radTexID);

	glTexImage2D (GL_TEXTURE_2D, 0, 4, texWidth, texHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, texData);

	glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

	delete [] texData;

	_radTexWidth = texWidth;
	_radTexHeight = texHeight;

	_radWinWidth = winWidth;
	_radWinHeight = winHeight;
}

void radUninit ()
{
	glDeleteTextures (1, &_radTexID);
}

void radBegin ()
{
	glViewport (0, 0, _radTexWidth, _radTexHeight);
}

void radEnd ()
{
	glBindTexture (GL_TEXTURE_2D, _radTexID);

	glCopyTexImage2D (GL_TEXTURE_2D, 0, GL_LUMINANCE, 0, 0, _radTexWidth, _radTexHeight, 0);

	glClearColor (0.0f, 0.0f, 0.0f, 0.5);
	glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	glViewport (0, 0, _radWinWidth, _radWinHeight);
}

void radDraw (int texRepeat, float texIncrement)
{
	if (texRepeat <= 0)
		return;

	float spost = 0.0f;
	float alphainc = 0.9f / texRepeat;
	float alpha = 0.2f;

	glDisable (GL_TEXTURE_GEN_S);
	glDisable (GL_TEXTURE_GEN_T);

	glEnable (GL_TEXTURE_2D);
	glDisable (GL_DEPTH_TEST);
	glBlendFunc (GL_SRC_ALPHA,GL_ONE);
	glEnable (GL_BLEND);
	glBindTexture (GL_TEXTURE_2D, _radTexID);

	_radViewOrtho ();

	alphainc = alpha / texRepeat;

	glBegin (GL_QUADS);

		for (int i = 0; i < texRepeat; i++)
		{
			glColor4f (1.0f, 1.0f, 1.0f, alpha);

			glTexCoord2f (0 + spost, 1 - spost);	glVertex2f (0,            0);
			glTexCoord2f (0 + spost, 0 + spost);	glVertex2f (0,            _radWinHeight);
			glTexCoord2f (1 - spost, 0 + spost);	glVertex2f (_radWinWidth, _radWinHeight);
			glTexCoord2f (1 - spost, 1 - spost);	glVertex2f (_radWinWidth, 0);

			spost += texIncrement;
			alpha = alpha - alphainc;
		}

	glEnd ();

	_radViewPerspective ();

	glEnable (GL_DEPTH_TEST);

	glDisable (GL_TEXTURE_2D);
	glDisable (GL_BLEND);

	glBindTexture (GL_TEXTURE_2D, 0);
}

void _radViewOrtho ()
{
	glMatrixMode (GL_PROJECTION);

	glPushMatrix ();

	glLoadIdentity ();

	glOrtho (0, 640 ,480 , 0, -1, 1);

	glMatrixMode (GL_MODELVIEW);

	glPushMatrix ();

	glLoadIdentity ();
}

void _radViewPerspective ()
{
	glMatrixMode (GL_PROJECTION);
	glPopMatrix ();
	glMatrixMode (GL_MODELVIEW);
	glPopMatrix ();
}