#include <windows.h>		
#include <gl\gl.h>			
#include <gl\glu.h>		
#include <gl\glaux.h>		

HDC			hDC=NULL;		
HGLRC		hRC=NULL;		
HWND		hWnd=NULL;		
HINSTANCE	hInstance;		

bool	keys[256];			
bool	active=TRUE;		
bool	fullscreen=TRUE;	

GLfloat		yrot;

GLfloat		tranx;	

GLfloat LightAmbient[]= { 0.3f, 0.3f, 0.3f, 1.0f }; 			
GLfloat LightDiffuse[]= { 0.8f, 1.0f, 0.8f, 1.0f };				
GLfloat LightPosition[]= { 0.0f, 2.0f, 0.0f, 1.0f };

LRESULT	CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);	

GLvoid ReSizeGLScene(GLsizei width, GLsizei height)		
{
	if (height==0)										
	{
		height=1;									
	}

	glViewport(0,0,width,height);						

	glMatrixMode(GL_PROJECTION);						
	glLoadIdentity();									

	// Calculate The Aspect Ratio Of The Window

	gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);

	glMatrixMode(GL_MODELVIEW);							
	glLoadIdentity();									
}

int InitGL(GLvoid)										
{
	glShadeModel(GL_SMOOTH);							
	glClearColor(0.0f, 0.0f, 0.2f, 0.5f);				
	glClearDepth(1.0f);									
	glEnable(GL_DEPTH_TEST);							
	glDepthFunc(GL_LEQUAL);								
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
   	glLightfv(GL_LIGHT1, GL_AMBIENT, LightAmbient);				
    glLightfv(GL_LIGHT1, GL_DIFFUSE, LightDiffuse);				
    glLightfv(GL_LIGHT1, GL_POSITION,LightPosition);			
    glEnable(GL_LIGHT1);
    glEnable(GL_LIGHTING);							
	return TRUE;										
}

int DrawGLScene(GLvoid)									
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);	
	glLoadIdentity();									
	gluLookAt(0.0f, 3.0f, -40.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f);

	glBegin(GL_QUADS);						
		glVertex3f(-20.0f, -1.0f, -20.0f);				
		glVertex3f(-20.0f, -1.0f, 20.0f);				
		glVertex3f(20.0f, -1.0f, 20.0f);				
		glVertex3f(20.0f, -1.0f, -20.0f);				
	glEnd();
    yrot += 5.0f;							
    if (keys[VK_RIGHT])							
    {
	yrot += 5.0f;							
    }

    if (keys[VK_LEFT])							
    {
	yrot -= 5.0f;							
    }
    if (keys[VK_UP])							
    {
	tranx -= 2.0f;							
    }

	return TRUE;										
}

GLvoid KillGLWindow(GLvoid)							
{
	if (fullscreen)										
	{
		ChangeDisplaySettings(NULL,0);				
		ShowCursor(TRUE);								
	}

	if (hRC)											
	{
		if (!wglMakeCurrent(NULL,NULL))				
		{
			MessageBox(NULL,"Release Of DC And RC Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		}

		if (!wglDeleteContext(hRC))					
		{
			MessageBox(NULL,"Release Rendering Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		}
		hRC=NULL;									
	}

	if (hDC && !ReleaseDC(hWnd,hDC))					
	{
		MessageBox(NULL,"Release Device Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		hDC=NULL;									
	}

	if (hWnd && !DestroyWindow(hWnd))				
	{
		MessageBox(NULL,"Could Not Release hWnd.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		hWnd=NULL;									
	}

	if (!UnregisterClass("OpenGL",hInstance))		
	{
		MessageBox(NULL,"Could Not Unregister Class.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		hInstance=NULL;								
	}
}


BOOL CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag)
{
	GLuint		PixelFormat;		
	WNDCLASS	wc;						
	DWORD		dwExStyle;			
	DWORD		dwStyle;				
	RECT		WindowRect;				
	WindowRect.left=(long)0;			
	WindowRect.right=(long)width;		
	WindowRect.top=(long)0;				
	WindowRect.bottom=(long)height;		

	fullscreen=fullscreenflag;			

	hInstance			= GetModuleHandle(NULL);				
	wc.style			= CS_HREDRAW | CS_VREDRAW | CS_OWNDC;	
	wc.lpfnWndProc		= (WNDPROC) WndProc;					
	wc.cbClsExtra		= 0;									
	wc.cbWndExtra		= 0;									
	wc.hInstance		= hInstance;							
	wc.hIcon			= LoadIcon(NULL, IDI_WINLOGO);			
	wc.hCursor			= LoadCursor(NULL, IDC_ARROW);			
	wc.hbrBackground	= NULL;								
	wc.lpszMenuName		= NULL;								
	wc.lpszClassName	= "OpenGL";								

	if (!RegisterClass(&wc))									
	{
		MessageBox(NULL,"Failed To Register The Window Class.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;											
	}
	
	if (fullscreen)											
	{
		DEVMODE dmScreenSettings;							
		memset(&dmScreenSettings,0,sizeof(dmScreenSettings));	
		dmScreenSettings.dmSize=sizeof(dmScreenSettings);		
		dmScreenSettings.dmPelsWidth	= width;				
		dmScreenSettings.dmPelsHeight	= height;			
		dmScreenSettings.dmBitsPerPel	= bits;				
		dmScreenSettings.dmFields=DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT;

		
		if (ChangeDisplaySettings(&dmScreenSettings,CDS_FULLSCREEN)!=DISP_CHANGE_SUCCESSFUL)
		{
		
			if (MessageBox(NULL,"The Requested Fullscreen Mode Is Not Supported By\nYour Video Card. Use Windowed Mode Instead?","NeHe GL",MB_YESNO|MB_ICONEXCLAMATION)==IDYES)
			{
				fullscreen=FALSE;		
			}
			else
			{
				
				MessageBox(NULL,"Program Will Now Close.","ERROR",MB_OK|MB_ICONSTOP);
				return FALSE;								
			}
		}
	}

	if (fullscreen)											
	{
		dwExStyle=WS_EX_APPWINDOW;							
		dwStyle=WS_POPUP;										
		ShowCursor(FALSE);									
	}
	else
	{
		dwExStyle=WS_EX_APPWINDOW | WS_EX_WINDOWEDGE;			
		dwStyle=WS_OVERLAPPEDWINDOW;							
	}

	AdjustWindowRectEx(&WindowRect, dwStyle, FALSE, dwExStyle);	

	// Create The Window

	if (!(hWnd=CreateWindowEx(	dwExStyle,						
								"OpenGL",							
								title,								
								dwStyle |							
								WS_CLIPSIBLINGS |					
								WS_CLIPCHILDREN,				
								0, 0,							
								WindowRect.right-WindowRect.left,	
								WindowRect.bottom-WindowRect.top,	
								NULL,								
								NULL,								
								hInstance,							
								NULL)))								
	{
		KillGLWindow();								
		MessageBox(NULL,"Window Creation Error.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;								
	}

	static	PIXELFORMATDESCRIPTOR pfd=				
	{
		sizeof(PIXELFORMATDESCRIPTOR),				
		1,										
		PFD_DRAW_TO_WINDOW |					
		PFD_SUPPORT_OPENGL |					
		PFD_DOUBLEBUFFER,							
		PFD_TYPE_RGBA,							
		bits,									
		0, 0, 0, 0, 0, 0,						
		0,										
		0,											
		0,										
		0, 0, 0, 0,								
		16,											
		0,											
		0,										
		PFD_MAIN_PLANE,							
		0,										
		0, 0, 0										
	};
	
	if (!(hDC=GetDC(hWnd)))							
	{
		KillGLWindow();								
		MessageBox(NULL,"Can't Create A GL Device Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;							
	}

	if (!(PixelFormat=ChoosePixelFormat(hDC,&pfd)))	
	{
		KillGLWindow();								
		MessageBox(NULL,"Can't Find A Suitable PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;							
	}

	if(!SetPixelFormat(hDC,PixelFormat,&pfd))	
	{
		KillGLWindow();							
		MessageBox(NULL,"Can't Set The PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;								
	}

	if (!(hRC=wglCreateContext(hDC)))				
	{
		KillGLWindow();								
		MessageBox(NULL,"Can't Create A GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;							
	}

	if(!wglMakeCurrent(hDC,hRC))				
	{
		KillGLWindow();								
		MessageBox(NULL,"Can't Activate The GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;								
	}

	ShowWindow(hWnd,SW_SHOW);						
	SetForegroundWindow(hWnd);						
	SetFocus(hWnd);									
	ReSizeGLScene(width, height);				

	if (!InitGL())									
	{
		KillGLWindow();								
		MessageBox(NULL,"Initialization Failed.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;								
	}

	return TRUE;									
}

LRESULT CALLBACK WndProc(	HWND	hWnd,		
							UINT	uMsg,		
							WPARAM	wParam,			
							LPARAM	lParam)		
{
	switch (uMsg)									
	{
		case WM_ACTIVATE:						
		{
			if (!HIWORD(wParam))				
			{
				active=TRUE;					
			}
			else
			{
				active=FALSE;						
			}

			return 0;								
		}

		case WM_SYSCOMMAND:							
		{
			switch (wParam)							
			{
				case SC_SCREENSAVE:					
				case SC_MONITORPOWER:				
				return 0;						
			}
			break;								
		}

		case WM_CLOSE:								
		{
			PostQuitMessage(0);					
			return 0;							
		}

		case WM_KEYDOWN:						
		{
			keys[wParam] = TRUE;					
			return 0;								
		}

		case WM_KEYUP:							
		{
			keys[wParam] = FALSE;				
			return 0;								
		}

		case WM_SIZE:								
		{
			ReSizeGLScene(LOWORD(lParam),HIWORD(lParam));  
			return 0;							
		}
	}

	// Pass All Unhandled Messages To DefWindowProc

	return DefWindowProc(hWnd,uMsg,wParam,lParam);
}

int WINAPI WinMain(	HINSTANCE	hInstance,			
					HINSTANCE	hPrevInstance,		
					LPSTR		lpCmdLine,			
					int			nCmdShow)			
{
	MSG		msg;									
	BOOL	done=FALSE;								

	// Ask The User Which Screen Mode They Prefer

	if (MessageBox(NULL,"Would You Like To Run In Fullscreen Mode?", "Start FullScreen?",MB_YESNO|MB_ICONQUESTION)==IDNO)
	{
		fullscreen=FALSE;						
	}

	// Create Our OpenGL Window

	if (!CreateGLWindow("NeHe's OpenGL Framework",640,480,16,fullscreen))
	{
		return 0;									
	}

	while(!done)									
	{
		if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))	
		{
			if (msg.message==WM_QUIT)				
			{
				done=TRUE;						
			}
			else									
			{
				TranslateMessage(&msg);			
				DispatchMessage(&msg);			
			}
		}
		else									
		{
		
			if (active)								
			{
				if (keys[VK_ESCAPE])				
				{
					done=TRUE;						
				}
				else								
				{
					DrawGLScene();					
					SwapBuffers(hDC);				
				}
			}

			if (keys[VK_F1])						
			{
				keys[VK_F1]=FALSE;				
				KillGLWindow();						
				fullscreen=!fullscreen;				
				// Recreate Our OpenGL Window

				if (!CreateGLWindow("NeHe's OpenGL Framework",640,480,16,fullscreen))
				{
					return 0;						
				}
			}
		}
	}

	// Shutdown

	KillGLWindow();								
	return (msg.wParam);						
}