小菜鸟的C++游戏编程学习日记(二)

                                                      作者：杨帆
                     
                       参考书籍：Beginning Game ProGramming(中文版)
                       学习时间：2016.7.27   

#include <windows.h>
#include <iostream>
#include <time.h>      //include header source

using namespace std;

const string APPTITLE = "Game Loop";
HWND hWnd;
HDC hDc;
bool gameover = false;

//local and draws a bitmap from file and then free the memory
//(not really suitable for a game loop but it's self contained)

void DrawBitmap(char* filename,int x,int y)
{
//load the bitmap image
HBITMAP image = (HBITMAP)LoadImage(0, "000.bmp", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
//read the bitmap's properties
BITMAP bmp;
GetObject(image, sizeof(BITMAP), &bmp);
//creat a device context for the bitmap
HDC hdcImage = CreateCompatibleDC(hDc);
SelectObject(hdcImage, image);
//draw the bitmap to the window (bit block transfer)
BitBlt(
hDc,                                //destination device context
x, y,                               //x,y location on destination
bmp.bmWidth, bmp.bmHeight,          //width,height of source bitmap
hdcImage,                           //source bitmap device context
0, 0,                               //start x,y on source bitmap
SRCCOPY                             //bit method
);
//delete the device context and bitmap
DeleteDC(hdcImage);
DeleteObject((HBITMAP)image);
}

//startup and loading code goes here
bool GameInit()
{
//start up the random number generator
srand((unsigned)time(NULL));
return true;
}

//update function called from inside game loop

void GameRun()
{
if (gameover == true)
{
return;
}
//get the drawing surface
RECT rect;
GetClientRect(hWnd, &rect);
//draw bitmap at random location
int x = rand() % (rect.right - rect.left);
int y = rand() % (rect.bottom - rect.top);
DrawBitmap("000.bmp", x, y);
}

//shut down code
void GameEnd()
{
//free the device
ReleaseDC(hWnd,hDc);
}

//window callback function

LRESULT CALLBACK WinProc(HWND hwnd,UINT message,WPARAM wparam,LPARAM lparam)
{
switch (message)
{
case WM_DESTROY:
gameover = true;
PostQuitMessage(0);
break;
default:
break;
}
return DefWindowProc(hwnd, message, wparam, lparam);
}

//register the window

ATOM MyRegisterWindowClass(HINSTANCE hInstance)
{
// creat a window class struct
WNDCLASSEX wc;
wc.cbClsExtra = 0;
wc.cbSize = sizeof(WNDCLASSEX);
wc.cbWndExtra = 0;
wc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hIcon = NULL;
wc.hIconSm = NULL;
wc.hInstance = hInstance;
wc.lpfnWndProc = (WNDPROC)WinProc;
wc.lpszClassName = APPTITLE.c_str();
wc.lpszMenuName = NULL;
wc.style = CS_HREDRAW | CS_VREDRAW;
return RegisterClassEx(&wc);
}

//helper function to create the window and refresh it
BOOL InitInstance(HINSTANCE hInstance,int nCmdShow)
{
//creat new window
hWnd = CreateWindow(
APPTITLE.c_str(),                   //ClassName
APPTITLE.c_str(),                   //WindowName
WS_OVERLAPPEDWINDOW,                //style
CW_USEDEFAULT, CW_USEDEFAULT,       //x,y position in window (use default)
800, 500,                           //window size
NULL, NULL,                         //WndParent      hMenu
hInstance,                          //Window instance
NULL                                //lParam
);

//was here an error creating the window
if (!hWnd)
{
return 0;
}

//display the window
ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);

//get device context for drawing
hDc = GetDC(hWnd);
return 1;
}

//Entry point function
int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nCmdShow)
{
MSG msg;

//creat window
MyRegisterWindowClass(hInstance);
if (!InitInstance(hInstance,nCmdShow))
{
return 0;
}

//initialize the game
if (!GameInit())
{
return 0;
}

//main message loop
while (!gameover)
{
//process windows events
if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
//process  game loop
GameRun();
}
//free game resource
GameEnd();
return msg.wParam;
}

          这里对比昨天主要是对消息循环进行了新的处理，使得游戏过程有了一个完整的循环过程。并且藉此和之前看过的一点视频学习了关于贴图的知识，利用之前有的资源写了另一份代码。效果如下(没错就是会动的):