Lesson 3 Nehe

#include <gl/opengl.h>

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

BOOL keys[256];
BOOL active = TRUE;
BOOL fullscreen = FALSE;

LRESULT CALLBACK WindowProc( HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);

GLvoid ReSizeGLScene(GLsizei width, GLsizei height){
    // 如果高为0 ， 则设置其为1
    if (height == 0) height = 1;
    // 设置可以看到的视角
    glViewport(0,0,width, height);

    // 设置投影矩阵
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    // 设置平截头体
    gluPerspective(45.0f, (GLdouble)width/(GLdouble)height, 0.1f, 100.0f);

    // 设置模型矩阵
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

GLvoid InitGL(){
    glShadeModel(GL_SMOOTH);
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    // 1.0f 为最大深度
    glClearDepth(1.0f);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LEQUAL);
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
}

BOOL DrawGLScene(){
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();
    glTranslatef(-1.5f, 0.0f, -6.0f);

    glBegin(GL_TRIANGLES);
        glColor3f(1.0f, 0.0f, 0.0f);
        glVertex3f(0.0f, 1.0f, 0.0f);

        glColor3f(0.0f, 1.0f, 0.0f);
        glVertex3f(-1.0f, -1.0f, 0.0f);

        glColor3f(0.0f, 0.0f, 1.0f);
        glVertex3f(1.0f, -1.0f, 0.0f);
    glEnd();

    glTranslatef(3.0f, 0.0f, 0.0f);
    glColor3f(0.0f, 0.0f, 1.0f);
    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(){
    if (fullscreen){
        ChangeDisplaySettings(NULL, 0);
        ShowCursor(FALSE);
    }

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

    // ReleaseDC 失败返回0， 成功返回非0
    if (hDC && !ReleaseDC(hWnd, hDC)){
        MessageBox(NULL, "释放DC失败", "错误", MB_OK);
        hDC = NULL;
    }

    if (hWnd && !DestroyWindow(hWnd)){
        MessageBox(NULL, "销毁窗口失败", "错误", MB_OK);
        hWnd = NULL;
    }

    if (!UnregisterClass("opengl", hInstance)){
        MessageBox(NULL, "反注册失败", "错误", MB_OK);
        hInstance = NULL;
    }
}

BOOL CreateGLWindow(char* title, int width, int height, int bits, HINSTANCE hInstance, bool fullscreenflag){
    GLuint PixelFormat;
    WNDCLASS wc;
    DWORD dwStyle;
    DWORD dwExStyle;


    RECT WindowRect;
    WindowRect.left = (long)0;
    WindowRect.right= (long)width;
    WindowRect.top  =  (long)0;
    WindowRect.bottom = (long)height;


    fullscreen = fullscreenflag;

    wc.hInstance = hInstance;
    wc.cbClsExtra  = 0;
    wc.cbWndExtra  = 0;
    wc.style       = CS_HREDRAW | CS_VREDRAW | CS_OWNDC;
    wc.lpfnWndProc = WindowProc;
    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);
        return FALSE;
    }

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

        // 设置显示模式
        if  (ChangeDisplaySettings(&dmScreenSetting, CDS_FULLSCREEN)!= DISP_CHANGE_SUCCESSFUL){
            if (MessageBox(NULL, "当前显卡不支持全屏操做
使用窗口模式?", "错误", MB_YESNO|MB_ICONEXCLAMATION) == IDYES){
                fullscreen = FALSE;
            }
            else{
                MessageBox(NULL, "程序将会被关闭", "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;
        //ShowCursor(TRUE);
    }

    dwStyle = dwStyle | WS_CLIPCHILDREN|WS_CLIPSIBLINGS;
    AdjustWindowRectEx(&WindowRect, dwStyle, FALSE, dwExStyle);

    if (!(hWnd = CreateWindowEx(dwExStyle, "opengl", title, dwStyle, 0,0, WindowRect.right-WindowRect.left, WindowRect.bottom-WindowRect.top, NULL, NULL, hInstance, NULL))){
        KillGLWindow();
        MessageBox(NULL, "不能创建一个窗口设备描述表", "错误", MB_OK);
        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,               // 忽略的色彩位
        0,                              // 无Alpha缓存
        0,                              // 忽略Shift Bit
        0,                              // 无累加缓存
        0, 0, 0, 0,                         // 忽略聚集位
        16,                             // 16位 Z-缓存 (深度缓存)
        0,                              // 无蒙板缓存
        0,                              // 无辅助缓存
        PFD_MAIN_PLANE,                         // 主绘图层
        0,                              // Reserved
        0, 0, 0                             // 忽略层遮罩
    };
    if (!(hDC = GetDC(hWnd))){
        KillGLWindow();
        MessageBox(NULL, "不能创建一个相匹配的像素模式", "错误", MB_OK|MB_ICONEXCLAMATION);
        return FALSE;
    }

    if (!(PixelFormat = ChoosePixelFormat(hDC, &pfd))){
        KillGLWindow();
        MessageBox(NULL, "不能设置像素格式", "错误", MB_OK|MB_ICONEXCLAMATION);
        return FALSE;
    }

    if (!SetPixelFormat(hDC, PixelFormat, &pfd)){
        KillGLWindow();
        MessageBox(NULL, "不能设置像素格式", "错误",MB_OK|MB_ICONEXCLAMATION);
        return FALSE;
    }

    if (!(hRC = wglCreateContext(hDC))){
        KillGLWindow();
        MessageBox(NULL, "不能创建当前的opengl渲染描述表", "错误", MB_OK|MB_ICONEXCLAMATION);
        return FALSE;
    }

    if (!wglMakeCurrent(hDC, hRC)){
        KillGLWindow();
        MessageBox(NULL, "不能激活当前的opengl渲染描述表", "错误", MB_OK);
        return FALSE;
    }

    ShowWindow(hWnd, SW_SHOW);
    // 激活窗口
    SetForegroundWindow(hWnd);
    // 接收键盘信息
    SetFocus(hWnd);
    ReSizeGLScene(width, height);

    InitGL();
    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;
        }
    case WM_CLOSE:
        {
            PostQuitMessage(0);
            return 0;
        }
    case WM_KEYUP:
        {
            keys[wParam] = FALSE;
            return 0;
        }
    case WM_KEYDOWN:
        {
            keys[wParam] = TRUE;
            return 0;
        }
    case WM_SIZE:
        {
            ReSizeGLScene(LOWORD(lParam), HIWORD(lParam));
            return 0;
        }
    }
    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, "是否在全屏模式下运行?", "提示", MB_YESNO|MB_ICONEXCLAMATION) == IDYES)
        fullscreen = TRUE;

    if (!CreateGLWindow("Lesson 3", 640, 480, 16, hInstance, 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;
                    if (!CreateGLWindow("Lesson 3", 640, 480, 16, hInstance, fullscreen))
                        return 0;
                }
            }

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