Lesson 2 Nehe

#include <gl/opengl.h>

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


BOOL keys[255];
BOOL active = TRUE;
BOOL fullscreen = TRUE;
LRESULT CALLBACK WindowProc(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(0.0f, 0.0f, 0.0f, 0.5f);

    glClearDepth(1.0f);
    glEnable(GL_DEPTH_TEST);

    glDepthFunc(GL_LEQUAL);

    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);

    return TRUE;
}

BOOL DrawwGLScene(GLvoid){
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glLoadIdentity();
    glTranslatef(-1.5f, 0.0f, -6.0f);
    glBegin(GL_TRIANGLES);
        glVertex3f( 0.0f,  1.0f, 0.0f);
        glVertex3f(-1.0f, -1.0f, 0.0f);
        glVertex3f( 1.0f, -1.0f, 0.0f);
    glEnd();

    glTranslatef(3.0f, 0.0f, 0.0f);
    glBegin(GL_QUADS);
        glVertex3f(-1.0f, 1.0f, 0.0f);
        glVertex3f( 1.0f, 1.0f, 0.0f);
        glVertex3f( 1.0f,-1.0f, 0.0f);
        glVertex3f(-1.0f,-1.0f, 0.0f);
    glEnd();

    return TRUE;
}

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

    if (hRC){
        if (!wglMakeCurrent(NULL, NULL))
            MessageBox(NULL, "释放DC 或 RC 失败", "关闭错误", MB_OK|MB_ICONEXCLAMATION);
        if (!wglDeleteContext(hRC))
            MessageBox(NULL, "释放RC 失败", "关闭错误", MB_OK|MB_ICONEXCLAMATION);
        hRC = NULL;
    }

    if (hDC && !ReleaseDC(hWnd, hDC)){
        MessageBox(NULL,"释放DC失败","关闭错误", MB_OK|MB_ICONEXCLAMATION);
        hDC = NULL;
    }

    if (hWnd && !DestroyWindow(hWnd)){
        MessageBox(NULL, "释放窗口失败", "关闭错误", MB_OK|MB_ICONEXCLAMATION);
        hWnd = NULL;
    }

    if (!UnregisterClass("opengl", hInstance)){
        MessageBox(NULL, "反注册窗口类失败","关闭错误", MB_OK|MB_ICONEXCLAMATION);
        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 = WindowProc;
    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.lpszClassName = "opengl";
    wc.lpszMenuName  = NULL;


    // 注册窗口类
    if (!RegisterClass(&wc)){
        MessageBox(NULL, "窗口注册失败", "错误", MB_OK|MB_ICONEXCLAMATION);
        return FALSE;
    }

    if (fullscreen){
        DEVMODE dmScreenSetting;
        memset(&dmScreenSetting, 0, sizeof(dmScreenSetting));
        dmScreenSetting.dmSize      = sizeof(dmScreenSetting);
        dmScreenSetting.dmPelsHeight  = height;
        dmScreenSetting.dmPelsWidth  = width;
        dmScreenSetting.dmBitsPerPel  = bits;
        dmScreenSetting.dmFields        = DM_BITSPERPEL|DM_PELSHEIGHT|DM_PELSWIDTH;

        // 设置显示模式
        if (ChangeDisplaySettings(&dmScreenSetting, CDS_FULLSCREEN) != DISP_CHANGE_SUCCESSFUL){
            //ErrorExit();
            if (MessageBox(NULL, "全屏模式在当前显卡设置失败.
使用小窗口模式？", "错误", MB_YESNO|MB_ICONEXCLAMATION) ==  IDYES){
                fullscreen = FALSE;
            }
            else{
                MessageBox(NULL, "程序将被关闭","错误",MB_OK|MB_ICONEXCLAMATION);
                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);

    //dwStyle = WS_CLIPSIBLINGS| WS_CLIPCHILDREN| dwStyle;
    // 创建窗口
    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, "创建窗口错误", "错误", MB_OK|MB_ICONEXCLAMATION);
        return FALSE;
    }

    static PIXELFORMATDESCRIPTOR pfd={
        sizeof(PIXELFORMATDESCRIPTOR),
        1,
        PFD_DOUBLEBUFFER|PFD_SUPPORT_OPENGL|PFD_DOUBLEBUFFER,
        PFD_TYPE_RGBA,
        bits,                    // 24-bit 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,            // accum bits ignored 
        16,                    // 32-bit z-buffer     
        0,                     // no stencil buffer 
        0,                     // no auxiliary buffer 
        PFD_MAIN_PLANE,        // main layer 
        0,                     // reserved 
        0, 0, 0                // layer masks ignored 
    }; 
    // 1. 利用句柄获取DC
    if (!(hDC = GetDC(hWnd))){
        KillGLWindow();
        MessageBox(NULL, "不能创建一个相匹配的像素格式","错误",MB_OK|MB_ICONEXCLAMATION);
        return FALSE;
    }
    // 2. 利用DC选择像素格式
    if (!(PixelFormat = ChoosePixelFormat(hDC, &pfd))){
        KillGLWindow();
        MessageBox(NULL, "选择像素格式错误", "错误", MB_OK|MB_ICONEXCLAMATION);
        return FALSE;
    }
    // 3. 设置像素格式
    if (!SetPixelFormat(hDC, PixelFormat, &pfd)){
        KillGLWindow();
        MessageBox(NULL, "设置像素格式错误", "错误", MB_OK|MB_ICONEXCLAMATION);
        return FALSE;
    }
    // 4.创建opengl 的设备描述表
    if (!(hRC = wglCreateContext(hDC))){
        KillGLWindow();
        MessageBox(NULL,"创建hRc误误", "错误", MB_OK|MB_ICONEXCLAMATION);
        return FALSE;
    }
    // 5. 两者相互绑定
    if (!wglMakeCurrent(hDC, hRC)){
        KillGLWindow();
        MessageBox(NULL, "不能激活当前的opengl设备描述表", "错误", MB_OK|MB_ICONEXCLAMATION);
        return FALSE;
    }
    //6. 进行相应的窗口操作
    ShowWindow(hWnd, SW_SHOW);
    SetForegroundWindow(hWnd);
    SetFocus(hWnd);
    ResizeGLScene(width, height);

    if (!InitGL()){
        KillGLWindow();
        MessageBox(NULL, "opengl 初始化失败", "错误", MB_OK|MB_ICONEXCLAMATION);
        return FALSE;
    }
    return TRUE;
}

LRESULT CALLBACK WindowProc( HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam ){
    switch(uMsg){
    case WM_ACTIVATE:
        {
            if (!HIWORD(wParam))
                active = TRUE;
            else
                active = FALSE;
            return 0;
        }
//      break;
    case WM_SYSCOMMAND:
        {
            switch(wParam){
            case SC_SCREENSAVE:
            case SC_MONITORPOWER:
                return 0;
            }
        }
        break;
    case WM_CLOSE:
        {
            PostQuitMessage(0);
            return 0;
        }
//      break;
    case WM_KEYUP:
        {
            keys[wParam] = TRUE;
            return 0;
        }
//      break;
    case WM_KEYDOWN:
        {
            keys[wParam] = FALSE;
            return 0;
        }
//      break;
    case WM_SIZE:
        {
            ResizeGLScene(LOWORD(lParam), LOWORD(lParam));
            return 0;
        }
//      break;
    }
    return DefWindowProc(hwnd, uMsg, wParam, lParam);
}

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

    if (MessageBox(NULL, "你想在全屏模式下运行吗？", "设置全屏运行模式", MB_YESNO|MB_ICONEXCLAMATION) == IDYES)
        fullscreen = TRUE;
    else
        fullscreen = FALSE;

    if (!CreateGLWindow("Lesson 2", 640, 480, 16, fullscreen)){
        MessageBox(NULL,"窗口创建失败", "错误", MB_OK|MB_ICONEXCLAMATION);
        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){
                // 窗口在激活状态
                if (keys[VK_ESCAPE]){
                    done = TRUE;
                }
                else{
                    DrawwGLScene();
                    SwapBuffers(hDC);
                }
                ///////
                if (keys[VK_F1]){
                    keys[VK_F1] = FALSE;
                    KillGLWindow();
                    fullscreen = !fullscreen;
                    if (!CreateGLWindow("Lesson 2", 640, 480, 16,fullscreen))
                        return 0;
                }
            }// end if 
        }// end if 
    }// end while 
    KillGLWindow();
    return (msg.wParam);
}