物体的加速运动(只受重力影响)

 

#include <Windows.h>

#include <iostream>

 

const int X=200,Y=50;    //程序窗口左上角相对于屏幕的坐标 

const int WIDTH=640,HEIGHT=480;  // //程序窗口的宽与高

DWORD tPre,tNow;      //tPre记录上一次绘图的时间，tNow记录此次准备绘图的时间

int x=0,y=0,vx=3,vy=0,gy=1;  //x、y表示物体的初始位置，vx、vy表示速度的变化量，gy表示重力加速度

 

HDC hdc,mdc,bufdc;

HBITMAP bg,dra;

RECT rect;

 

void MyPaint(HDC);

LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);

 

int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nCmdShow)

{

 const std::string szTitle="加速运动";

 WNDCLASS winclass={CS_HREDRAW|CS_VREDRAW,WndProc,0,0,hInstance,LoadIcon(NULL,IDI_APPLICATION),

  LoadCursor(NULL,IDC_ARROW),(HBRUSH)GetStockObject(WHITE_BRUSH),NULL,szTitle.c_str()};

 if(!RegisterClass(&winclass))

  return false;

 HWND hWnd=CreateWindow(szTitle.c_str(),szTitle.c_str(),WS_OVERLAPPEDWINDOW,X,Y,WIDTH,HEIGHT,

  NULL,NULL,winclass.hInstance,NULL);

 if(0==hWnd)

  return 0;

 ShowWindow(hWnd,SW_SHOWDEFAULT);

 UpdateWindow(hWnd);

 MSG msg;

 ZeroMemory(&msg,sizeof(MSG));

 while(msg.message!=WM_QUIT)

 {

  if(PeekMessage(&msg,NULL,0,0,PM_REMOVE))

  {

   TranslateMessage(&msg);

   DispatchMessage(&msg);

  }

  else

  {

   tNow=GetTickCount(); 

   while(tNow-tPre>=40)

    MyPaint(hdc);

  }

 }

 return msg.wParam;

}

 

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

{

 HBITMAP bmp;

 switch(message)

 {

 case WM_CREATE:

  {

   hdc=GetDC(hWnd);

   mdc=CreateCompatibleDC(hdc);

   bufdc=CreateCompatibleDC(hdc);

   bmp=CreateCompatibleBitmap(hdc,WIDTH,HEIGHT);

   SelectObject(mdc,bmp);

   //加载物体位图

   bg=(HBITMAP)LoadImage(NULL,"bg.bmp",IMAGE_BITMAP,0,0,LR_LOADFROMFILE);

   dra=(HBITMAP)LoadImage(NULL,"dra.bmp",IMAGE_BITMAP,0,0,LR_LOADFROMFILE);

   GetClientRect(hWnd,&rect);  //取得内部窗口区域大小

  }

  break;

 

 case WM_KEYDOWN:

  {

   if(wParam==VK_ESCAPE)

    DestroyWindow(hWnd);

  }

  break;

 case WM_DESTROY:

  {

   DeleteDC(bufdc);

   DeleteDC(mdc);

   DeleteObject(bg);

   DeleteObject(dra);

   ReleaseDC(hWnd,hdc);

   PostQuitMessage(0);

  }

  break;

 default:

  return DefWindowProc(hWnd,message,wParam,lParam);

 }

 return 0;

}

 

void MyPaint(HDC hdc)

{

 //贴背景图

 SelectObject(bufdc,bg);

 BitBlt(mdc,0,0,WIDTH,HEIGHT,bufdc,0,0,SRCCOPY);

 //贴物体图

 SelectObject(bufdc,dra);

 BitBlt(mdc,x,y,50,50,bufdc,50,0,SRCAND);

 BitBlt(mdc,x,y,50,50,bufdc,0,0,SRCPAINT);

 BitBlt(hdc,0,0,WIDTH,HEIGHT,mdc,0,0,SRCCOPY);

 

 x+=vx;  //计算x轴方向物体坐标

 vy+=gy;  //计算y轴方向速度分量

 y+=vy;  //计算y轴方向贴图坐标

 

 if(x<=rect.right)

 {

  if(y>=rect.bottom-50)

  {

   y=rect.bottom-50;

   vy=-vy-1;

  }

 }

 

 else

 {

  x=0;

  if(y>=rect.bottom-50)

  {

   y=rect.bottom-50;

   vy=-vy-1;

  }

 }

 tPre=GetTickCount();

}