#include <windows.h>		// Header File For Windows
#include <gl\gl.h>		// Header File For The OpenGL32 Library
#include <gl\glu.h>		// Header File For The GLu32 Library
#include <gl\glaux.h>		// Header File For The GLaux Library

static	HGLRC hRC;		// Permanent Rendering Context
static	HDC hDC;		// Private GDI Device Context

BOOL	keys[256];		// Array Used For The Keyboard Routine

BOOL	twinkle;		// Twinkling Stars
BOOL	tp;			// 'T' Key Pressed?

const	num=50;			// Number Of Stars To Draw

typedef struct			// Create A Structure For Star
{
	int r, g, b;		// Stars Color
	GLfloat dist;		// Stars Distance From Center
	GLfloat angle;		// Stars Current Angle
}
stars;				// Structures Name Is stars
stars star[num];		// Make 'star' Array Of 'num' Using Info From The Structure 'stars'

GLfloat	zoom=-15.0f;		// Viewing Distance Away From Stars
GLfloat tilt=90.0f;		// Tilt The View
GLfloat	spin;			// Spin Twinkling Stars

GLuint	loop;			// General loop Variable
GLuint	texture[1];		// Storage For One Texture

// Load Bitmap And Convert To A Texture
GLvoid LoadGLTextures()
{
	// Load Texture
	AUX_RGBImageRec *texture1;				// Record To Store RBG Data From The Bitmap

	texture1 = auxDIBImageLoad("Data/star.bmp");
	if (!texture1)						// Check If The Texture Loaded
	{
		exit(1);					// If Not, Exit With An Error Message
	}

	glGenTextures(1, &texture[0]);				// Generate 1 Texture

	// Create Linear Filtered Texture
	glBindTexture(GL_TEXTURE_2D, texture[0]);
	glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
	glTexImage2D(GL_TEXTURE_2D, 0, 3, texture1->sizeX, texture1->sizeY, 0, GL_RGB, GL_UNSIGNED_BYTE, texture1->data);
};

GLvoid InitGL(GLsizei Width, GLsizei Height)	// This Will Be Called Right After The GL Window Is Created
{
	LoadGLTextures();			// Load The Texture ( ADD )
	glEnable(GL_TEXTURE_2D);		// Enable Texture Mapping ( ADD )

	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);	// This Will Clear The Background Color To Black
	glClearDepth(1.0);			// Enables Clearing Of The Depth Buffer

	glShadeModel(GL_SMOOTH);		// Enables Smooth Color Shading

	glMatrixMode(GL_PROJECTION);		// Select The Projection Matrix
	glLoadIdentity();			// Reset The Projection Matrix

	gluPerspective(45.0f,(GLfloat)Width/(GLfloat)Height,0.1f,100.0f);	// Calculate The Aspect Ratio Of The Window

	glMatrixMode(GL_MODELVIEW);		// Select The Modelview Matrix
	glBlendFunc(GL_SRC_ALPHA,GL_ONE);	// Set The Blending Function For Translucency
	glEnable(GL_BLEND);			// Enable Blending

	for (loop=0; loop<num; loop++)				// Create A Loop That Goes Through All The Stars
	{
		star[loop].angle=0.0f;				// Start All The Stars At Angle Zero

		star[loop].dist=(float(loop)/num)*5.0f;		// Calculate Distance From The Center
		star[loop].r=rand()%256;			// Give star[loop] A Random Red Intensity
		star[loop].g=rand()%256;			// Give star[loop] A Random Green Intensity
		star[loop].b=rand()%256;			// Give star[loop] A Random Blue Intensity
	}
}

GLvoid DrawGLScene(GLvoid)
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);		// Clear The Screen And The Depth Buffer
	glBindTexture(GL_TEXTURE_2D, texture[0]);			// Select Our Texture

	for (loop=0; loop<num; loop++)					// Loop Through All The Stars
	{
		glLoadIdentity();					// Reset The View Before We Draw Each Star
		glTranslatef(0.0f,0.0f,zoom);				// Zoom Into The Screen (Using The Value In 'zoom')
		glRotatef(tilt,1.0f,0.0f,0.0f);				// Tilt The View (Using The Value In 'tilt')

		glRotatef(star[loop].angle,0.0f,1.0f,0.0f);		// Rotate To The Current Stars Angle
		glTranslatef(star[loop].dist,0.0f,0.0f);		// Move Forward On The X Plane

		glRotatef(-star[loop].angle,0.0f,1.0f,0.0f);		// Cancel The Current Stars Angle
		glRotatef(-tilt,1.0f,0.0f,0.0f);			// Cancel The Screen Tilt

		if (twinkle)						// Twinkling Stars Enabled
		{
			// Assign A Color Using Bytes
			glColor4ub(star[(num-loop)-1].r,star[(num-loop)-1].g,star[(num-loop)-1].b,255);
			glBegin(GL_QUADS);				// Begin Drawing The Textured Quad
				glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,-1.0f, 0.0f);
				glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,-1.0f, 0.0f);
				glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 0.0f);
				glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 0.0f);
			glEnd();					// Done Drawing The Textured Quad
		}

		glRotatef(spin,0.0f,0.0f,1.0f);			// Rotate The Star On The Z Axis
		// Assign A Color Using Bytes
		glColor4ub(star[loop].r,star[loop].g,star[loop].b,255);
		glBegin(GL_QUADS);				// Begin Drawing The Textured Quad
			glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,-1.0f, 0.0f);
			glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,-1.0f, 0.0f);
			glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 0.0f);
			glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 0.0f);
		glEnd();					// Done Drawing The Textured Quad

		spin+=0.01f;					// Used To Spin The Stars
		star[loop].angle+=float(loop)/num;		// Changes The Angle Of A Star
		star[loop].dist-=0.01f;				// Changes The Distance Of A Star

		if (star[loop].dist<0.0f)			// Is The Star In The Middle Yet
		{
			star[loop].dist+=5.0f;			// Move The Star 5 Units From The Center
			star[loop].r=rand()%256;		// Give It A New Red Value
			star[loop].g=rand()%256;		// Give It A New Green Value
			star[loop].b=rand()%256;		// Give It A New Blue Value
		}
	}
}

		if (keys['T'] && !tp)				// Is T Being Pressed And Is tp FALSE
		{
			tp=TRUE;				// If So, Make tp TRUE
			twinkle=!twinkle;			// Make twinkle Equal The Opposite Of What It Is
		}

		if (!keys['T'])			// Has The T Key Been Released
		{
			tp=FALSE;		// If So, make tp FALSE
		}

		if (keys[VK_UP])		// Is Up Arrow Being Pressed
		{
			tilt-=0.5f;		// Tilt The Screen Up
		}

		if (keys[VK_DOWN])		// Is Down Arrow Being Pressed
		{
			tilt+=0.5f;		// Tilt The Screen Down
		}

		if (keys[VK_PRIOR])		// Is Page Up Being Pressed
		{
			zoom-=0.2f;		// Zoom Out
		}

		if (keys[VK_NEXT])		// Is Page Down Being Pressed
		{
			zoom+=0.2f;		// Zoom In
		}
	}
}