// set display mode 
if (FAILED(lpdd->SetDisplayMode(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP,0,0)))
   return(0);

// clear ddsd and set size
DDRAW_INIT_STRUCT(ddsd); 

// enable valid fields
ddsd.dwFlags = DDSD_CAPS | DDSD_BACKBUFFERCOUNT;

// set the backbuffer count field to 1, use 2 for triple buffering
ddsd.dwBackBufferCount = 1;

// request a complex, flippable
ddsd.ddsCaps.dwCaps = DDSCAPS_PRIMARYSURFACE | DDSCAPS_COMPLEX | DDSCAPS_FLIP;

// create the primary surface
if (FAILED(lpdd->CreateSurface(&ddsd, &lpddsprimary, NULL)))
   return(0);

// now query for attached surface from the primary surface

// this line is needed by the call
ddsd.ddsCaps.dwCaps = DDSCAPS_BACKBUFFER;

// get the attached back buffer surface
if (FAILED(lpddsprimary->GetAttachedSurface(&ddsd.ddsCaps, &lpddsback)))
  return(0);

// build up the palette data array
for (int color=1; color < 255; color++)
    {
    // fill with random RGB values
    palette[color].peRed   = rand()%256;
    palette[color].peGreen = rand()%256;
    palette[color].peBlue  = rand()%256;

    // set flags field to PC_NOCOLLAPSE
    palette[color].peFlags = PC_NOCOLLAPSE;
    } // end for color

// now fill in entry 0 and 255 with black and white
palette[0].peRed     = 0;
palette[0].peGreen   = 0;
palette[0].peBlue    = 0;
palette[0].peFlags   = PC_NOCOLLAPSE;

palette[255].peRed   = 255;
palette[255].peGreen = 255;
palette[255].peBlue  = 255;
palette[255].peFlags = PC_NOCOLLAPSE;

// make color 1 yellow
palette[1].peRed     = 255;
palette[1].peGreen   = 255;
palette[1].peBlue    = 0;
palette[1].peFlags   = PC_NOCOLLAPSE;

// create the palette object
if (FAILED(lpdd->CreatePalette(DDPCAPS_8BIT | DDPCAPS_ALLOW256 | 
                                DDPCAPS_INITIALIZE, 
                                palette,&lpddpal, NULL)))
return(0);

// finally attach the palette to the primary surface
if (FAILED(lpddsprimary->SetPalette(lpddpal)))
   return(0);

// initialize all the happy faces
for (int face = 0; face < 100; face++)
    {
    // set random position
    happy_faces[face].x = rand()%SCREEN_WIDTH;
    happy_faces[face].y = rand()%SCREEN_HEIGHT;    

    // set random velocity (-2,+2)
    happy_faces[face].xv = -2 + rand()%5;
    happy_faces[face].yv = -2 + rand()%5;

    } // end for face

// return success or failure or your own return code here
return(1);

} // end Game_Init

/////////////////////////////////////////////////////////////

int Game_Shutdown(void *parms = NULL, int num_parms = 0)
{
// this is called after the game is exited and the main event
// loop while is exited, do all you cleanup and shutdown here


// now the back buffer surface
if (lpddpal)
   {
   lpddpal->Release();
   lpddpal = NULL;
   } // end if

// now the back buffer surface
if (lpddsback)
   {
   lpddsback->Release();
   lpddsback = NULL;
   } // end if

// now the primary surface
if (lpddsprimary)
   {
   lpddsprimary->Release();
   lpddsprimary = NULL;
   } // end if

// now blow away the IDirectDraw4 interface
if (lpdd)
   {
   lpdd->Release();
   lpdd = NULL;
   } // end if

// return success or failure or your own return code here
return(1);

} // end Game_Shutdown

// WINMAIN ////////////////////////////////////////////////

int WINAPI WinMain(	HINSTANCE hinstance,
					HINSTANCE hprevinstance,
					LPSTR lpcmdline,
					int ncmdshow)
{

WNDCLASSEX winclass; // this will hold the class we create
HWND	   hwnd;	 // generic window handle
MSG		   msg;		 // generic message
HDC        hdc;      // graphics device context

// first fill in the window class stucture
winclass.cbSize         = sizeof(WNDCLASSEX);
winclass.style			= CS_DBLCLKS | CS_OWNDC | 
                          CS_HREDRAW | CS_VREDRAW;
winclass.lpfnWndProc	= WindowProc;
winclass.cbClsExtra		= 0;
winclass.cbWndExtra		= 0;
winclass.hInstance		= hinstance;
winclass.hIcon			= LoadIcon(NULL, IDI_APPLICATION);
winclass.hCursor		= LoadCursor(NULL, IDC_ARROW); 
winclass.hbrBackground	= (HBRUSH)GetStockObject(BLACK_BRUSH);
winclass.lpszMenuName	= NULL;
winclass.lpszClassName	= WINDOW_CLASS_NAME;
winclass.hIconSm        = LoadIcon(NULL, IDI_APPLICATION);

// save hinstance in global
hinstance_app = hinstance;

// register the window class
if (!RegisterClassEx(&winclass))
	return(0);

// create the window
if (!(hwnd = CreateWindowEx(NULL,                  // extended style
                            WINDOW_CLASS_NAME,     // class
						    "DirectDraw Software Clipping Demo", // title
						    WS_POPUP | WS_VISIBLE,
					 	    0,0,	  // initial x,y
						    SCREEN_WIDTH,SCREEN_HEIGHT,  // initial width, height
						    NULL,	  // handle to parent 
						    NULL,	  // handle to menu
						    hinstance,// instance of this application
						    NULL)))	// extra creation parms
return(0);

// save main window handle
main_window_handle = hwnd;

// initialize game here
Game_Init();

// enter main event loop
while(TRUE)
	{
    // test if there is a message in queue, if so get it
	if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))
	   { 
	   // test if this is a quit
       if (msg.message == WM_QUIT)
           break;
	
	   // translate any accelerator keys
	   TranslateMessage(&msg);

	   // send the message to the window proc
	   DispatchMessage(&msg);
	   } // end if
    
       // main game processing goes here
       Game_Main();
       
	} // end while

// closedown game here
Game_Shutdown();

// return to Windows like this
return(msg.wParam);

} // end WinMain

///////////////////////////////////////////////////////////

void Blit_Clipped(int x, int y,          // position to draw bitmap
                  int width, int height, // size of bitmap in pixels
                  UCHAR *bitmap,         // pointer to bitmap data
                  UCHAR *video_buffer,   // pointer to video buffer surface
                  int   mempitch)        // video pitch per line
{
// this function blits and clips the image sent in bitmap to the 
// destination surface pointed to by video_buffer
// the function assumes a 640x480x8 mode 

// first do trivial rejections of bitmap, is it totally invisible?
if ((x >= SCREEN_WIDTH) || (y>= SCREEN_HEIGHT) ||
    ((x + width) <= 0) || ((y + height) <= 0))
return;

// clip source rectangle
// pre-compute the bounding rect to make life easy
int x1 = x;
int y1 = y;
int x2 = x1 + width - 1;
int y2 = y1 + height -1;

// upper left hand corner first
if (x1 < 0)
   x1 = 0;

if (y1 < 0)
   y1 = 0;

// now lower left hand corner
if (x2 >= SCREEN_WIDTH)
    x2 = SCREEN_WIDTH-1;

if (y2 >= SCREEN_HEIGHT)
    y2 = SCREEN_HEIGHT-1;

// now we know to draw only the portions of the bitmap from (x1,y1) to (x2,y2)
// compute offsets into bitmap on x,y axes, we need this to compute starting point
// to rasterize from
int x_off = x1 - x;
int y_off = y1 - y;

// compute number of columns and rows to blit
int dx = x2 - x1 + 1;
int dy = y2 - y1 + 1;

// compute starting address in video_buffer 
video_buffer += (x1 + y1*mempitch);

// compute starting address in bitmap to scan data from
bitmap += (x_off + y_off*width);

// at this point bitmap is pointing to the first pixel in the bitmap that needs to
// be blitted, and video_buffer is pointing to the memory location on the destination
// buffer to put it, so now enter rasterizer loop

UCHAR pixel; // used to read/write pixels

for (int index_y = 0; index_y < dy; index_y++)
     {
     // inner loop, where the action takes place
     for (int index_x = 0; index_x < dx; index_x++)
          {
          // read pixel from source bitmap, test for transparency and plot
          if ((pixel = bitmap[index_x]))
              video_buffer[index_x] = pixel;

          } // end for index_x
     
          // advance pointers
          video_buffer+=mempitch;  // bytes per scanline
          bitmap      +=width;     // bytes per bitmap row

     } // end for index_y

} // end Blit_Clipped