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(此节内容对应NEHE教程第13课)

本节主要说明OpenGL结合WINDOW 创建并使用2D字体

作法

1.声明显示列表base = glGenLists(96); 2.创建新的FONT font = CreateFont(WinAPI) 3.选择我们需要的字体 oldfont = (HFONT)SelectObject(hDC, font);(WinAPI) 4.创建显示列表 wglUseFontBitmaps(hDC, 32, 96, base);从32~128字符。 按照ASII码进行存储。显示时候也是按照此逻辑进行寻找，如A对应65 则在显示列表65进行寻找 5.设置显示列表基础值 glListBase(base - 32); 原因：假设字符A的ASII为32，那么在第4步骤上A存储在显示列表第0位。在从显示列表从0位获取A时，就需要将最开始的32编译去掉 6.使用显示列表进行文字绘制 glCallLists(strlen(text), GL_UNSIGNED_BYTE, text); 图像字体使用的是显示列表，声明N个显示列表。每个显示列表用来存放一个字符，当显示文字时调用显示列表进行绘制。其中字符的ASII码对应显示列表的值 说明：显示列表创建过程 应该在工程初始化中进行，保证仅执行一次 步骤1~4 属于显示列表创建过程，步骤5 是显示列表重定位函数，结合逻辑使用。不是必须使用函数 步骤6在文字绘制时进行调用

#include "header.h"#include 
   
    			// Header File For Variable Argument RoutinesHDC			hDC=NULL;	// Private GDI Device ContextHGLRC		hRC=NULL;		// Permanent Rendering ContextHWND		hWnd=NULL;		// Holds Our Window HandleHINSTANCE	hInstance;		// Holds The Instance Of The ApplicationGLuint	base;				// Base Display List For The Font SetGLfloat	cnt1;				// 1st Counter Used To Move Text & For ColoringGLfloat	cnt2;				// 2nd Counter Used To Move Text & For Coloringbool	keys[256];			// Array Used For The Keyboard Routinebool	active=TRUE;		// Window Active Flag Set To TRUE By Defaultbool	fullscreen=TRUE;	// Fullscreen Flag Set To Fullscreen Mode By DefaultLRESULT	CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);	// Declaration For WndProcGLvoid BuildFont(GLvoid)								// Build Our Bitmap Font{	HFONT	font;									// Windows Font ID	HFONT	oldfont;								// Used For Good House Keeping	base = glGenLists(96);								// Storage For 96 Characters	font = CreateFont(	-24,							// Height Of Font						0,					// Width Of Font						0,					// Angle Of Escapement						0,					// Orientation Angle						FW_BOLD,				// Font Weight						FALSE,					// Italic						FALSE,					// Underline						FALSE,					// Strikeout						ANSI_CHARSET,				// Character Set Identifier						OUT_TT_PRECIS,				// Output Precision						CLIP_DEFAULT_PRECIS,			// Clipping Precision						ANTIALIASED_QUALITY,			// Output Quality						FF_DONTCARE|DEFAULT_PITCH,		// Family And Pitch						"Courier New");				// Font Name	oldfont = (HFONT)SelectObject(hDC, font);                                       // Selects The Font We Want	wglUseFontBitmaps(hDC, 32, 96, base);		                                // Builds 96 Characters Starting At Character 32	SelectObject(hDC, oldfont);							// Selects The Font We Want	DeleteObject(font);								// Delete The Font}GLvoid KillFont(GLvoid)									// Delete The Font List{	glDeleteLists(base, 96);							// Delete All 96 Characters}GLvoid glPrint(const char *fmt, ...)					// Custom GL "Print" Routine{	char		text[256];					// Holds Our String	va_list		ap;						// Pointer To List Of Arguments	if (fmt == NULL)						// If There's No Text		return;							// Do Nothing	va_start(ap, fmt);						// Parses The String For Variables	    vsprintf(text, fmt, ap);					// And Converts Symbols To Actual Numbers	va_end(ap);							// Results Are Stored In Text	glPushAttrib(GL_LIST_BIT);					// Pushes The Display List Bits	glListBase(base - 32);						// Sets The Base Character to 32	glCallLists(strlen(text), GL_UNSIGNED_BYTE, text);	        // Draws The Display List Text	glPopAttrib();							// Pops The Display List Bits}GLvoid ReSizeGLScene(GLsizei width, GLsizei height)		        // Resize And Initialize The GL Window{	if (height==0)							// Prevent A Divide By Zero By	{		height=1;						// Making Height Equal One	}	glViewport(0,0,width,height);					// Reset The Current Viewport	glMatrixMode(GL_PROJECTION);					// Select The Projection Matrix	glLoadIdentity();						// Reset The Projection Matrix	// Calculate The Aspect Ratio Of The Window	gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);	glMatrixMode(GL_MODELVIEW);					// Select The Modelview Matrix	glLoadIdentity();						// Reset The Modelview Matrix}int InitGL(GLvoid)							// All Setup For OpenGL Goes Here{	glShadeModel(GL_SMOOTH);					// Enable Smooth Shading	glClearColor(0.0f, 0.0f, 0.0f, 0.5f);				// Black Background	glClearDepth(1.0f);						// Depth Buffer Setup	glEnable(GL_DEPTH_TEST);					// Enables Depth Testing	glDepthFunc(GL_LEQUAL);						// The Type Of Depth Testing To Do	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);	// Really Nice Perspective Calculations	BuildFont();							// Build The Font	return TRUE;							// Initialization Went OK}int DrawGLScene(GLvoid)							// Here's Where We Do All The Drawing{	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);	// Clear Screen And Depth Buffer	glLoadIdentity();							// Reset The Current Modelview Matrix	glTranslatef(0.0f,0.0f,-1.0f);						// Move One Unit Into The Screen	// Pulsing Colors Based On Text Position	glColor3f(1.0f*float(cos(cnt1)),1.0f*float(sin(cnt2)),1.0f-0.5f*float(cos(cnt1+cnt2)));	// Position The Text On The Screen	glRasterPos2f(-0.45f+0.05f*float(cos(cnt1)), 0.32f*float(sin(cnt2))); 	glPrint("Active OpenGL Text With NeHe - %7.2f", cnt1);	// Print GL Text To The Screen	cnt1+=0.051f;										// Increase The First Counter	cnt2+=0.005f;										// Increase The First Counter	return TRUE;										// Everything Went OK}GLvoid KillGLWindow(GLvoid)								        // Properly Kill The Window{	if (fullscreen)										// Are We In Fullscreen Mode?	{		ChangeDisplaySettings(NULL,0);					                // If So Switch Back To The Desktop		ShowCursor(TRUE);								// Show Mouse Pointer	}	if (hRC)										// Do We Have A Rendering Context?	{		if (!wglMakeCurrent(NULL,NULL))					                // Are We Able To Release The DC And RC Contexts?		{			MessageBox(NULL,"Release Of DC And RC Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);		}		if (!wglDeleteContext(hRC))						        // Are We Able To Delete The RC?		{			MessageBox(NULL,"Release Rendering Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);		}		hRC=NULL;									// Set RC To NULL	}	if (hDC && !ReleaseDC(hWnd,hDC))					                // Are We Able To Release The DC	{		MessageBox(NULL,"Release Device Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);		hDC=NULL;									// Set DC To NULL	}	if (hWnd && !DestroyWindow(hWnd))					                // Are We Able To Destroy The Window?	{		MessageBox(NULL,"Could Not Release hWnd.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);		hWnd=NULL;									// Set hWnd To NULL	}	if (!UnregisterClass("OpenGL",hInstance))			                        // Are We Able To Unregister Class	{		MessageBox(NULL,"Could Not Unregister Class.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);		hInstance=NULL;									// Set hInstance To NULL	}	KillFont();}BOOL CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag){	GLuint		PixelFormat;			        // Holds The Results After Searching For A Match	WNDCLASS	wc;					// Windows Class Structure	DWORD		dwExStyle;				// Window Extended Style	DWORD		dwStyle;				// Window Style	RECT		WindowRect;				// Grabs Rectangle Upper Left / Lower Right Values	WindowRect.left=(long)0;			        // Set Left Value To 0	WindowRect.right=(long)width;		                // Set Right Value To Requested Width	WindowRect.top=(long)0;			 	        // Set Top Value To 0	WindowRect.bottom=(long)height;		                // Set Bottom Value To Requested Height	fullscreen=fullscreenflag;			        // Set The Global Fullscreen Flag	hInstance			= GetModuleHandle(NULL);// Grab An Instance For Our Window	wc.style			= CS_HREDRAW | CS_VREDRAW | CS_OWNDC;	// Redraw On Size, And Own DC For Window.	wc.lpfnWndProc		= (WNDPROC) WndProc;				// WndProc Handles Messages	wc.cbClsExtra		= 0;						// No Extra Window Data	wc.cbWndExtra		= 0;						// No Extra Window Data	wc.hInstance		= hInstance;					// Set The Instance	wc.hIcon			= LoadIcon(NULL, IDI_WINLOGO);		// Load The Default Icon	wc.hCursor			= LoadCursor(NULL, IDC_ARROW);		// Load The Arrow Pointer	wc.hbrBackground	= NULL;						// No Background Required For GL	wc.lpszMenuName		= NULL;						// We Don't Want A Menu	wc.lpszClassName	= "OpenGL";					// Set The Class Name	if (!RegisterClass(&wc))						// Attempt To Register The Window Class	{		MessageBox(NULL,"Failed To Register The Window Class.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;							// Return FALSE	}		if (fullscreen)								// Attempt Fullscreen Mode?	{		DEVMODE dmScreenSettings;					// Device Mode		memset(&dmScreenSettings,0,sizeof(dmScreenSettings));	        // Makes Sure Memory's Cleared		dmScreenSettings.dmSize=sizeof(dmScreenSettings);		// Size Of The Devmode Structure		dmScreenSettings.dmPelsWidth	= width;			// Selected Screen Width		dmScreenSettings.dmPelsHeight	= height;			// Selected Screen Height		dmScreenSettings.dmBitsPerPel	= bits;				// Selected Bits Per Pixel		dmScreenSettings.dmFields=DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT;		// Try To Set Selected Mode And Get Results.  NOTE: CDS_FULLSCREEN Gets Rid Of Start Bar.		if (ChangeDisplaySettings(&dmScreenSettings,CDS_FULLSCREEN)!=DISP_CHANGE_SUCCESSFUL)		{			// If The Mode Fails, Offer Two Options.  Quit Or Use Windowed Mode.			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;		// Windowed Mode Selected.  Fullscreen = FALSE			}			else			{				// Pop Up A Message Box Letting User Know The Program Is Closing.				MessageBox(NULL,"Program Will Now Close.","ERROR",MB_OK|MB_ICONSTOP);				return FALSE;									// Return FALSE			}		}	}	if (fullscreen)												// Are We Still In Fullscreen Mode?	{		dwExStyle=WS_EX_APPWINDOW;								        // Window Extended Style		dwStyle=WS_POPUP;										// Windows Style		ShowCursor(FALSE);										// Hide Mouse Pointer	}	else	{		dwExStyle=WS_EX_APPWINDOW | WS_EX_WINDOWEDGE;			// Window Extended Style		dwStyle=WS_OVERLAPPEDWINDOW;					// Windows Style	}	AdjustWindowRectEx(&WindowRect, dwStyle, FALSE, dwExStyle);		// Adjust Window To True Requested Size	// Create The Window	if (!(hWnd=CreateWindowEx(	dwExStyle,							// Extended Style For The Window								"OpenGL",				// Class Name								title,					// Window Title								dwStyle |				// Defined Window Style								WS_CLIPSIBLINGS |			// Required Window Style								WS_CLIPCHILDREN,			// Required Window Style								0, 0,					// Window Position								WindowRect.right-WindowRect.left,	// Calculate Window Width								WindowRect.bottom-WindowRect.top,	// Calculate Window Height								NULL,					// No Parent Window								NULL,					// No Menu								hInstance,				// Instance								NULL)))					// Dont Pass Anything To WM_CREATE	{		KillGLWindow();								                // Reset The Display		MessageBox(NULL,"Window Creation Error.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								                // Return FALSE	}	static	PIXELFORMATDESCRIPTOR pfd=				        // pfd Tells Windows How We Want Things To Be	{		sizeof(PIXELFORMATDESCRIPTOR),				        // Size Of This Pixel Format Descriptor		1,								// Version Number		PFD_DRAW_TO_WINDOW |						// Format Must Support Window		PFD_SUPPORT_OPENGL |						// Format Must Support OpenGL		PFD_DOUBLEBUFFER,						// Must Support Double Buffering		PFD_TYPE_RGBA,							// Request An RGBA Format		bits,								// Select Our Color Depth		0, 0, 0, 0, 0, 0,						// Color Bits Ignored		0,								// No Alpha Buffer		0,								// Shift Bit Ignored		0,								// No Accumulation Buffer		0, 0, 0, 0,							// Accumulation Bits Ignored		16,								// 16Bit Z-Buffer (Depth Buffer)  		0,								// No Stencil Buffer		0,								// No Auxiliary Buffer		PFD_MAIN_PLANE,							// Main Drawing Layer		0,								// Reserved		0, 0, 0								// Layer Masks Ignored	};		if (!(hDC=GetDC(hWnd)))							// Did We Get A Device Context?	{		KillGLWindow();								// Reset The Display		MessageBox(NULL,"Can't Create A GL Device Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	if (!(PixelFormat=ChoosePixelFormat(hDC,&pfd)))	// Did Windows Find A Matching Pixel Format?	{		KillGLWindow();								// Reset The Display		MessageBox(NULL,"Can't Find A Suitable PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	if(!SetPixelFormat(hDC,PixelFormat,&pfd))		                        // Are We Able To Set The Pixel Format?	{		KillGLWindow();								// Reset The Display		MessageBox(NULL,"Can't Set The PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	if (!(hRC=wglCreateContext(hDC)))				                // Are We Able To Get A Rendering Context?	{		KillGLWindow();								// Reset The Display		MessageBox(NULL,"Can't Create A GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	if(!wglMakeCurrent(hDC,hRC))					                // Try To Activate The Rendering Context	{		KillGLWindow();								// Reset The Display		MessageBox(NULL,"Can't Activate The GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	ShowWindow(hWnd,SW_SHOW);						        // Show The Window	SetForegroundWindow(hWnd);						        // Slightly Higher Priority	SetFocus(hWnd);									// Sets Keyboard Focus To The Window	ReSizeGLScene(width, height);					                // Set Up Our Perspective GL Screen	if (!InitGL())									// Initialize Our Newly Created GL Window	{		KillGLWindow();								// Reset The Display		MessageBox(NULL,"Initialization Failed.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	return TRUE;									// Success}LRESULT CALLBACK WndProc(	HWND	hWnd,			// Handle For This Window							UINT	uMsg,			// Message For This Window							WPARAM	wParam,			// Additional Message Information							LPARAM	lParam)			// Additional Message Information{	switch (uMsg)									// Check For Windows Messages	{		case WM_ACTIVATE:							// Watch For Window Activate Message		{			if (!HIWORD(wParam))					        // Check Minimization State			{				active=TRUE;						// Program Is Active			}			else			{				active=FALSE;						// Program Is No Longer Active			}			return 0;							// Return To The Message Loop		}		case WM_SYSCOMMAND:							// Intercept System Commands		{			switch (wParam)							// Check System Calls			{				case SC_SCREENSAVE:					// Screensaver Trying To Start?				case SC_MONITORPOWER:				        // Monitor Trying To Enter Powersave?				return 0;						// Prevent From Happening			}			break;								// Exit		}		case WM_CLOSE:								// Did We Receive A Close Message?		{			PostQuitMessage(0);						// Send A Quit Message			return 0;							// Jump Back		}		case WM_KEYDOWN:							// Is A Key Being Held Down?		{			keys[wParam] = TRUE;					// If So, Mark It As TRUE			return 0;							// Jump Back		}		case WM_KEYUP:								// Has A Key Been Released?		{			keys[wParam] = FALSE;					// If So, Mark It As FALSE			return 0;							// Jump Back		}		case WM_SIZE:								// Resize The OpenGL Window		{			ReSizeGLScene(LOWORD(lParam),HIWORD(lParam));  // LoWord=Width, HiWord=Height			return 0;							// Jump Back		}	}	// Pass All Unhandled Messages To DefWindowProc	return DefWindowProc(hWnd,uMsg,wParam,lParam);}int WINAPI WinMain(	HINSTANCE	hInstance,			// Instance					HINSTANCE	hPrevInstance,		// Previous Instance					LPSTR		lpCmdLine,			// Command Line Parameters					int			nCmdShow)		// Window Show State{	MSG		msg;								// Windows Message Structure	BOOL	done=FALSE;								// Bool Variable To Exit Loop	// 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;							// Windowed Mode	}	// Create Our OpenGL Window	if (!CreateGLWindow("NeHe's Bitmap Font Tutorial",640,480,16,fullscreen))	{		return 0;									// Quit If Window Was Not Created	}	while(!done)									// Loop That Runs While done=FALSE	{		if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))	// Is There A Message Waiting?		{			if (msg.message==WM_QUIT)				// Have We Received A Quit Message?			{				done=TRUE;						// If So done=TRUE			}			else								// If Not, Deal With Window Messages			{				TranslateMessage(&msg);				// Translate The Message				DispatchMessage(&msg);				// Dispatch The Message			}		}		else										// If There Are No Messages		{			// Draw The Scene.  Watch For ESC Key And Quit Messages From DrawGLScene()			if ((active && !DrawGLScene()) || keys[VK_ESCAPE])	// Active?  Was There A Quit Received?			{				done=TRUE;							// ESC or DrawGLScene Signalled A Quit			}			else									// Not Time To Quit, Update Screen			{				SwapBuffers(hDC);					// Swap Buffers (Double Buffering)			}			if (keys[VK_F1])						// Is F1 Being Pressed?			{				keys[VK_F1]=FALSE;					// If So Make Key FALSE				KillGLWindow();						// Kill Our Current Window				fullscreen=!fullscreen;				// Toggle Fullscreen / Windowed Mode				// Recreate Our OpenGL Window				if (!CreateGLWindow("NeHe's Bitmap Font Tutorial",640,480,16,fullscreen))				{					return 0;						// Quit If Window Was Not Created				}			}		}	}	// Shutdown	KillGLWindow();									// Kill The Window	return (msg.wParam);							// Exit The Program}
   

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