DX笔记之六------游戏画面绘图之透明特效的制作方法

#include <windows.h>

//全局变量声明
HINSTANCE hInst;
HBITMAP bg,dra; //声明两个位图对象，分别存储背景图与前景恐龙图
HDC     mdc;       //声明一个内存DC"mdc"，用来暂存位图


//全局函数声明
ATOM     MyRegisterClass(HINSTANCE hInstance);
BOOL     InitInstance(HINSTANCE, int);
LRESULT CALLBACK    WndProc(HWND, UINT, WPARAM, LPARAM);
void     MyPaint(HDC hdc);
////****Winmain函数，程序入口点函数**************************************
int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR     lpCmdLine,
                     int       nCmdShow)
{
    MSG msg;
    MyRegisterClass(hInstance);
    if (!InitInstance (hInstance, nCmdShow)) 
    {
        return FALSE;
    }
    //消息循环
    while (GetMessage(&msg, NULL, 0, 0)) 
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}
//****设计一个窗口类，类似填空题，使用窗口结构体*************************
ATOM MyRegisterClass(HINSTANCE hInstance)
{
    WNDCLASSEX wcex;
    wcex.cbSize            = sizeof(WNDCLASSEX); 
    wcex.style            = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc    = (WNDPROC)WndProc;
    wcex.cbClsExtra        = 0;
    wcex.cbWndExtra        = 0;
    wcex.hInstance        = hInstance;
    wcex.hIcon            = NULL;
    wcex.hCursor        = NULL;
    wcex.hCursor        = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground    = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName    = NULL;
    wcex.lpszClassName    = TEXT("canvas");
    wcex.hIconSm        = NULL;
    return RegisterClassEx(&wcex);
}
//****初始化函数*************************************
// 1.建立与窗口DC兼容的内存DC
// 2.从文件加载背景图与恐龙图
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
    HWND hWnd;
    HDC hdc;
    hInst = hInstance;
    hWnd = CreateWindow(TEXT("canvas"), TEXT("绘图窗口") , WS_OVERLAPPEDWINDOW,
    CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);
    if (!hWnd)
    {
        return FALSE;
    }
    MoveWindow(hWnd,10,10,600,450,true);
    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);
    hdc = GetDC(hWnd);                     //获得窗口DC
    mdc = CreateCompatibleDC(hdc);           //创建与窗口兼容的内存DC(mdc)
    bg = (HBITMAP)LoadImage(NULL,TEXT("bg.bmp"),IMAGE_BITMAP,600,450,LR_LOADFROMFILE); 
    //加载背景图到bg中;
    dra = (HBITMAP)LoadImage(NULL,TEXT("dra.bmp"),IMAGE_BITMAP,170,99,LR_LOADFROMFILE); 
    //加载恐龙图到dra中;
    MyPaint(hdc);
    ReleaseDC(hWnd,hdc);
    return TRUE;
}
//****自定义绘图函数*********************************
//透明贴图
void MyPaint(HDC hdc)
{
    SelectObject(mdc,bg);
    BitBlt(hdc,0,0,600,450,mdc,0,0,SRCCOPY);    //先将背景图贴到显示窗口中
    SelectObject(mdc,dra);                      //选用恐龙图到"mdc"中
    BitBlt(hdc,280,320,85,99,mdc,85,0,SRCAND);    //进行制作贴图的第一步骤，即将屏蔽图与背景图做"AND"运算，屏蔽图在整张恐龙图中，最左上角起始位置点得坐标为（85,0），BitBlt()函数中最后一个Raster参数值设置为SRCAND。
    BitBlt(hdc,280,320,85,99,mdc,0,0,SRCPAINT);    //进行制作透明贴图的第二步骤，即将前景图与背景图做"OR"运算，前景图在整张恐龙图中，最左上角起始位置的坐标为(0,0),BitBlt()函数最后一个参数值设置为SRCPAINT。
}
//****消息处理函数**********************************
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    PAINTSTRUCT ps;
    HDC hdc;
    switch (message)
    {
        case WM_PAINT:     //窗口重绘消息
        hdc = BeginPaint(hWnd, &ps);
        MyPaint(hdc);
        EndPaint(hWnd, &ps);
        break;
    case WM_DESTROY:     //窗口结束消息
        DeleteDC(mdc);
        DeleteObject(bg);
        DeleteObject(dra);
        PostQuitMessage(0);
        break;
    default:     //其他消息
        return DefWindowProc(hWnd, message, wParam, lParam);
   }
   return 0;
}