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  • OPENGL4_变换

    几种变换的几何意义说明

    http://blog.csdn.net/onafioo/article/details/22094247


    变换的执行顺序问题

    正常顺序

    1 视图(观察)变换

    2 模型变换

    3 投影变换

    4 视口变换


    变换相关OpenGL函数说明

    glViewport(GLint x,GLint y,GLsizei width,GLsizei height)
    设置视口

    glMatrixMode (GLenum mode)
    指定哪一个矩阵堆栈是下一个矩阵操作的目标
    可选值
    GL_MODELVIEW,对模型视景矩阵堆栈应用随后的矩阵操作.
    GL_PROJECTION,对投影矩阵应用随后的矩阵操作.
    GL_TEXTURE,对纹理矩阵堆栈应用随后的矩阵操作.

    glLoadIdentity();
    清空glMatrixMode 指定的类型的矩阵(变成单位矩阵),相当于复位

    gluPerspective(GLdouble fovy,GLdouble aspect,GLdouble zNear,GLdouble zFar)
    设置视景体,在glMatrixMode(GL_PROJECTION)下使用
    fovy:视角
    aspect:屏幕纵宽比
    zNear:近裁剪面z值
    zFar:远裁剪面z值

    gluLookAt(GLdoble eyex,GLdouble eyey,GLdouble eyez,GLdouble centerx,GLdouble centery,GLdouble centerz,GLdouble upx,GLdouble upy,GLdouble upz);
    设置摄像机朝向
    9个参数分别代表,摄像机位置xyz,摄像机看向的目标位置xyz,摄像机朝向xyz(摄像机和这个向量的关系类似人眼和人站立的方向),一般设置为(0,1,0),代表人正常站立,眼睛朝前看

    glTranslatef (GLfloat x, GLfloat y, GLfloat z);
    平移

    glScalef (GLfloat x, GLfloat y, GLfloat z);
    缩放

    glRotatef (GLfloat angle, GLfloat x, GLfloat y, GLfloat z)
    angle:旋转角度
    xyz:旋转轴

    代码中几种变换出现的顺序

    //视口变换

    glViewport(0,0,width,height);

    //投影变换

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

    //模型视图变换

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    //摄像机位置,观察点,摄像机方位

    gluLookAt();

    后面跟模型变换的平移,旋转,缩放


    原因

    Opengl让矩阵和顶点做左乘操作

    例如C*B*A*v,实际是先乘A矩阵,然后B,然后C,所以变换顺序上,代码出现的顺序是反序。

    所以下面代码意思为,先缩放,在旋转,然后再移动(下面代码在执行前已经)

    glLoadIdentity();//清空模型观察矩阵(之前已经执行了glMatrixMode(GL_MODELVIEW)切换到了模型观察矩阵,并且已经对矩阵做过平移旋转等操作,所以要清空)
    
    glTranslatef(8.0f,0.0f,-18.9f);//移动
    glRotatef(rotateAngle,0.0f,1.0f,0.0f);//旋转
    glScalef(1.5f,1.5f,1.5f);//缩放
    
    glBegin(GL_TRIANGLES);
    glColor3f(1.0f,0.0f,1.0f);// 设置当前色为紫色
    glVertex3f( 0.0f, 1.0f, 0.0f);//对象绕自身的轴旋转,必须让对象的中心坐标总是(0.0f,0,0f,0,0f)
    glVertex3f(-1.0f,-1.0f, 0.0f);
    glVertex3f( 1.0f,-1.0f, 0.0f);
    rotateAngle+=0.1;
    glEnd();




    完整代码及效果

    #include "stdafx.h"
    #include "Nehe_Base.h"
    
    #include "GL.H"				// Header File For The OpenGL32 Library
    #include "GLU.H"			// Header File For The GLu32 Library
    #include "GLAUX.H"			// Header File For The Glaux Library
    
    HDC			hDC=NULL;		// Private GDI Device Context
    HGLRC		hRC=NULL;		// Permanent Rendering Context
    HWND		hWnd=NULL;		// Holds Our Window Handle
    HINSTANCE	hInstance;		// Holds The Instance Of The Application
    
    bool	keys[256];			// Array Used For The Keyboard Routine
    bool	active=TRUE;		// Window Active Flag Set To TRUE By Default
    bool	fullscreen=TRUE;	// Fullscreen Flag Set To Fullscreen Mode By Default
    
    GLfloat rotateAngle;
    
    LRESULT	CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);	// Declaration For WndProc
    
    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);						
    	glLoadIdentity();									
    	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
    	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
    	
    	gluLookAt(0.0f,0.0f,10.0f,0.0f,0.0f,0.0f,0.0f,1.0f,0.0f);
    	//移动是相对当前位置移动(第一次移动相对与屏幕中心0,0,0下一次再移动时相对的就是本次移动后的位置了)
    	//向屏幕内移动18.9个单位,这样1个单位(1米)对应480/(2*tan(22.5)*(18.9+0.1)= 30像素
    	glTranslatef(0.0f,0.0f,-18.9f);
    
    	// 绘制不连续线段,把屏幕分成9部分
    	glBegin(GL_LINES);
    	glColor3f(1.0f,1.0f,1.0f);// 设置当前色为红色
    	// 横线
    	glVertex3f( -21.0f, 3.0f, 0.0f);					
    	glVertex3f(21.0f, 3.0f, 0.0f);				
    	glVertex3f( -21.0f, -3.0f, 0.0f);
    	glVertex3f( 21.0f, -3.0f, 0.0f);
    	// 竖线
    	glVertex3f( -3.0f, 8.0f, 0.0f);					
    	glVertex3f(-3.0f, -8.0f, 0.0f);				
    	glVertex3f( 3.0f, 8.0f, 0.0f);
    	glVertex3f( 3.0f, -8.0f, 0.0f);
    	glEnd();
    
    	
    	// 绘制点
    	glBegin(GL_POINTS);
    	glColor3f(1.0f,0.0f,0.0f);// 设置当前色为红色
    	glVertex3f( -8.0f, 5.5f, 0.0f);
    	glVertex3f( -7.5f, 5.5f, 0.0f);
    	glVertex3f( -7.0f, 5.5f, 0.0f);
    	glEnd();
    
    	// 绘制不闭合折线
    	glBegin(GL_LINE_STRIP);
    	glColor3f(1.0f,1.0f,0.0f);// 设置当前色为黄色
    	glVertex3f( -2.0f, 5.5f, 0.0f);
    	glVertex3f( 2.0f, 5.5f, 0.0f);
    	glVertex3f( -2.0f, 4.0f, 0.0f);
    	glVertex3f( 2.0f, 4.0f, 0.0f);
    	glEnd();
    
    	// 绘制闭合折线
    	glBegin(GL_LINE_LOOP);
    	glColor3f(0.0f,0.0f,1.0f);// 设置当前色为蓝色
    	glVertex3f( 6.0f, 6.0f, 0.0f);
    	glVertex3f( 4.0f, 4.0f, 0.0f);
    	glVertex3f( 8.0f, 4.0f, 0.0f);
    	glEnd();
    
    	// 绘制多组独立填充三角形(以下绘制2个三角形)
    	glBegin(GL_TRIANGLES);
    	glColor3f(1.0f,0.0f,0.0f);// 设置当前色为红色
    	glVertex3f( -9.0f, 1.0f, 0.0f);
    	glVertex3f(-8.0f,-1.0f, 0.0f);
    	glVertex3f( -10.0f,-1.0f, 0.0f);
    
    	glVertex3f( -6.0f, 1.0f, 0.0f);
    	glVertex3f(-5.0f,-1.0f, 0.0f);
    	glVertex3f( -7.0f,-1.0f, 0.0f);
    	glEnd();
    
    	// 绘制三角形带
    	glBegin(GL_TRIANGLE_STRIP);//(以下绘制3个连续三角形)
    	//第一个三角形由点123逆时针构成
    	//第二个三角形由点324逆时针构成
    	//第三个三角形由点345逆时针构成
    	glColor3f(1.0f,0.0f,0.0f);// 设置当前色为红色
    	glVertex3f( -2.0f,-1.0f, 0.0f);//点1
    	glVertex3f(0.0f,-1.0f, 0.0f);//点2
    	glVertex3f( -1.0f, 1.0f, 0.0f);//点3
    	glColor3f(0.0f,1.0f,0.0f);// 设置当前色为绿色
    	glVertex3f( 1.0f,1.0f, 0.0f);//点4
    	glColor3f(0.0f,0.0f,1.0f);// 设置当前色为蓝色
    	glVertex3f(2.5f,2.5f, 0.0f);//点5
    	glEnd();
    
    	//旋转
    	//glLoadIdentity();
    	glTranslatef(0.0f,0.0f,18.9f);
    	glTranslatef(8.0f,0.0f,-18.9f);
    	glRotatef(rotateAngle,0.0f,1.0f,0.0f);
    	//glScalef(1.5f,1.5f,1.5f);
    	glBegin(GL_TRIANGLES);
    	glColor3f(1.0f,0.0f,1.0f);// 设置当前色为紫色
    	glVertex3f( 0.0f, 1.0f, 0.0f);
    	glVertex3f(-1.0f,-1.0f, 0.0f);
    	glVertex3f( 1.0f,-1.0f, 0.0f);
    	rotateAngle+=0.1;
    	glEnd();
    
    	
    
    	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
    	}
    }
    
    /*	This Code Creates Our OpenGL Window.  Parameters Are:					*
     *	title			- Title To Appear At The Top Of The Window				*
     *	width			- Width Of The GL Window Or Fullscreen Mode				*
     *	height			- Height Of The GL Window Or Fullscreen Mode			*
     *	bits			- Number Of Bits To Use For Color (8/16/24/32)			*
     *	fullscreenflag	- Use Fullscreen Mode (TRUE) Or Windowed Mode (FALSE)	*/
     
    BOOL CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag)
    {
    	//当我们要求Windows为我们寻找相匹配的象素格式时,Windows寻找结束后将模式值保存在变量PixelFormat中。
    	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
    Your 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
    	}
    
    
    	//像素格式明确了OpenGL绘制平面的特性,如象素缓冲区是单缓冲还是双缓冲,数据是 RGBA方式还是Color Index方式等。
    	//每个OpenGL显示设备一般用名为PIXELFORMATDESCRIPTOR的结构来表示某个的像素格式
    	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 OpenGL Framework",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)								// Program Active?
    			{
    				if (keys[VK_ESCAPE])				// Was ESC Pressed?
    				{
    					done=TRUE;						// ESC Signalled A Quit
    				}
    				else								// Not Time To Quit, Update Screen
    				{
    					DrawGLScene();					// Draw The Scene
    					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 OpenGL Framework",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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  • 原文地址:https://www.cnblogs.com/nafio/p/9137609.html
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