[]win32下绘制正弦曲线

#define TWOPI (2*3.14159)
 ...
LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
     static int  cxClient, cyClient ;
     HDC         hdc ;
     int         i ;
     PAINTSTRUCT ps ;
     POINT       apt [NUM] ;
     
     switch (message)
     {
     case WM_SIZE:
          cxClient = LOWORD (lParam) ;
          cyClient = HIWORD (lParam) ;
          return 0 ;
          
     case WM_PAINT:
          hdc = BeginPaint (hwnd, &ps) ;
          
          MoveToEx (hdc, 0,        cyClient / 2, NULL) ;
          LineTo   (hdc, cxClient, cyClient / 2) ;
          
          for (i = 0 ; i < NUM ; i++)
          {
              [color=#FF0000] apt[i].x = i * cxClient / NUM ;
               apt[i].y = (int) (cyClient / 2 * (1-sin (TWOPI * i / NUM))) ;[/color]               
          }
          
          Polyline (hdc, apt, NUM) ;
          return 0 ;
          
     case WM_DESTROY:
          PostQuitMessage (0) ;
          return 0 ;
     }
     return DefWindowProc (hwnd, message, wParam, lParam) ;
}