OpenGL学习笔记(一)

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OpenGL学习笔记

一.目前网上流传的OpenGL学习笔记主要可以分为三种，一种是以红宝书，蓝宝书为主的，使用glut绘制窗口，第二种则是像Nehe使用windows的API，第三种是在windows下使用的以MFC类库为主的教程，我的笔记里主要是使用第二种方式。

二.绘制窗口

全部代码如下：

#include <windows.h>#include <gl/gl.h>#include <gl/glu.h>#include <gl/glaux.h> #include <gl/glut.h>HGLRC hRC=NULL;HDC hDC=NULL;HWND hWnd=NULL;HINSTANCE hInstance;boolkeys[256];boolactive=TRUE;boolfullscreen=TRUE;LRESULTCALLBACK 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();gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);glMatrixMode(GL_MODELVIEW);glLoadIdentity();}int InitGL(GLvoid){glShadeModel(GL_SMOOTH);glClearColor(1.0f, 0.0f, 0.0f, 0.0f);glClearDepth(1.0f);glEnable(GL_DEPTH_TEST);glDepthFunc(GL_LEQUAL);glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);return TRUE;}int DrawGLScene(GLvoid){glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glLoadIdentity();return TRUE;}GLvoid KillGLWindow(GLvoid){if (fullscreen){ChangeDisplaySettings(NULL,0);ShowCursor(TRUE);}if (hRC){if (!wglMakeCurrent(NULL,NULL)){MessageBox(NULL,TEXT("释放DC或RC失败。"),TEXT("关闭错误"),MB_OK | MB_ICONINFORMATION);}if (!wglDeleteContext(hRC)){MessageBox(NULL,TEXT("释放DC或RC失败。"),TEXT("关闭错误"),MB_OK | MB_ICONINFORMATION);}hRC=NULL;}if (hDC && !ReleaseDC(hWnd,hDC)){MessageBox(NULL,TEXT("释放DC或RC失败。"),TEXT("关闭错误"),MB_OK | MB_ICONINFORMATION);hDC=NULL;}if (hWnd && !DestroyWindow(hWnd)){MessageBox(NULL,TEXT("释放窗口句柄失败。"),TEXT("关闭错误"),MB_OK | MB_ICONINFORMATION);hWnd=NULL;}if (!UnregisterClass(TEXT("OpenGL"),hInstance)){MessageBox(NULL,TEXT("不能注销窗口类。"),TEXT("关闭错误"),MB_OK | MB_ICONINFORMATION);hInstance=NULL;}}BOOL CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag){GLuintPixelFormat;WNDCLASSwc;DWORDdwExStyle;DWORDdwStyle;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= TEXT("OpenGL");if (!RegisterClass(&wc)){MessageBox(NULL,TEXT("注册窗口失败"),TEXT("错误"),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,TEXT("全屏模式在当前显卡上设置失败！/n使用窗口模式？"),TEXT("NeHe G"),MB_YESNO|MB_ICONEXCLAMATION)==IDYES){fullscreen=FALSE;}else{MessageBox(NULL,TEXT("程序将被关闭"),TEXT("错误"),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);if (!(hWnd=CreateWindowEx(dwExStyle,TEXT("OpenGL"),title,WS_CLIPSIBLINGS |WS_CLIPCHILDREN |dwStyle,0, 0,WindowRect.right-WindowRect.left,WindowRect.bottom-WindowRect.top,NULL,NULL,hInstance,NULL))){KillGLWindow();MessageBox(NULL,TEXT("不能创建一个窗口设备描述表"),TEXT("错误"),MB_OK|MB_ICONEXCLAMATION);return FALSE;}staticPIXELFORMATDESCRIPTOR 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,TEXT("不能创建一种相匹配的像素格式"),TEXT("错误"),MB_OK|MB_ICONEXCLAMATION);return FALSE;}if (!(PixelFormat=ChoosePixelFormat(hDC,&pfd))){KillGLWindow();MessageBox(NULL,TEXT("不能设置像素格式"),TEXT("错误"),MB_OK|MB_ICONEXCLAMATION);return FALSE;}if(!SetPixelFormat(hDC,PixelFormat,&pfd)){KillGLWindow();MessageBox(NULL,TEXT("不能设置像素格式"),TEXT("错误"),MB_OK|MB_ICONEXCLAMATION);return FALSE;}if (!(hRC=wglCreateContext(hDC))){KillGLWindow();MessageBox(NULL,TEXT("不能创建OpenGL渲染描述表"),TEXT("错误"),MB_OK|MB_ICONEXCLAMATION);return FALSE;}if(!wglMakeCurrent(hDC,hRC)){KillGLWindow();MessageBox(NULL,TEXT("不能激活当前的OpenGL渲然描述表"),TEXT("错误"),MB_OK|MB_ICONEXCLAMATION);return FALSE;}ShowWindow(hWnd,SW_SHOW);SetForegroundWindow(hWnd);SetFocus(hWnd);ReSizeGLScene(width, height);if (!InitGL()){KillGLWindow();MessageBox(NULL,TEXT("Initialization Failed."),TEXT("ERROR"),MB_OK|MB_ICONEXCLAMATION);return FALSE;}return TRUE;}LRESULT CALLBACK WndProc(HWNDhWnd, UINTuMsg,WPARAMwParam,LPARAMlParam){switch (uMsg){case WM_ACTIVATE:{if (!HIWORD(wParam)){active=TRUE;}else{active=FALSE;// 程序不再激活}return 0;// 返回消息循环}case WM_SYSCOMMAND:// 系统中断命令{switch (wParam)// 检查系统调用{case SC_SCREENSAVE:// 屏保要运行?case SC_MONITORPOWER:// 显示器要进入节电模式?return 0;// 阻止发生}break;// 退出}case WM_CLOSE:// 收到Close消息?{PostQuitMessage(0);// 发出退出消息return 0;// 返回}case WM_KEYDOWN:// 有键按下么?{keys[wParam] = TRUE;// 如果是，设为TRUEreturn 0;// 返回}case WM_KEYUP:// 有键放开么?{keys[wParam] = FALSE;// 如果是，设为FALSEreturn 0;// 返回}case WM_SIZE:// 调整OpenGL窗口大小{ReSizeGLScene(LOWORD(lParam),HIWORD(lParam));// LoWord=Width,HiWord=Heightreturn 0;// 返回}}return DefWindowProc(hWnd,uMsg,wParam,lParam);}int WINAPI WinMain(HINSTANCEhInstance,HINSTANCEhPrevInstance,LPSTRlpCmdLine,intnCmdShow){MSGmsg;// Windowsx消息结构BOOLdone=FALSE;// 用来退出循环的Bool 变量//这段代码完全可选。程序弹出一个消息窗口，询问用户是否希望在全屏模式下运行。如果用户单击NO按钮，fullscreen变量从缺省的TRUE改变为FALSE，程序也改在窗口模式下运行。 // 提示用户选择运行模式if (MessageBox(NULL,TEXT("你想在全屏模式下运行么？"),TEXT( "设置全屏模式"),MB_YESNO|MB_ICONQUESTION)==IDNO){fullscreen=FALSE;// FALSE为窗口模式}// 创建OpenGL窗口if (!CreateGLWindow("NeHe's OpenGL程序框架",640,480,16,fullscreen)){return 0;// 失败退出}while(!done)// 保持循环直到 done=TRUE{if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))// 有消息在等待吗?{if (msg.message==WM_QUIT)// 收到退出消息?{done=TRUE;// 是，则done=TRUE}else// 不是，处理窗口消息{TranslateMessage(&msg);// 翻译消息DispatchMessage(&msg);// 发送消息}}else// 如果没有消息{if (active)// 程序激活的么?{if (keys[VK_ESCAPE])// ESC 按下了么?{done=TRUE;// ESC 发出退出信号}else// 不是退出的时候，刷新屏幕{DrawGLScene();// 绘制场景SwapBuffers(hDC);// 交换缓存 (双缓存)}}if (keys[VK_F1])// F1键按下了么?{keys[VK_F1]=FALSE;// 若是，使对应的Key数组中的值为 FALSEKillGLWindow();// 销毁当前的窗口fullscreen=!fullscreen;// 切换全屏 / 窗口模式// 重建 OpenGL 窗口if (!CreateGLWindow("NeHe's OpenGL 程序框架",640,480,16,fullscreen)){return 0;// 如果窗口未能创建，程序退出}}}}KillGLWindow();// 销毁窗口return (msg.wParam);// 退出程序}

三.全部代码可以总结为

GLvoid ReSizeGLScene(GLsizei width, GLsizei height);

//重构窗口大小，当移动或者缩放窗口时候有效

int InitGL(GLvoid);

//初始化GL的属性

int DrawGLScene(GLvoid)；

//具体的绘制函数

GLvoid KillGLWindow(GLvoid);

//关闭各种对象

BOOL CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag);

//创建窗口的函数

LRESULT CALLBACK WndProc( HWND hWnd, UINT uMsg,WPARAM wParam,LPARAM lParam);