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LPDIRECTDRAWCLIPPER mainClipper;
lpDD->CreateClipper(0, mainClipper, NULL);
mainClipper->SetHWnd(0, hwnd);
primarySurface->SetClipper(mainClipper);
That should create a new clipper, set it to update it's clipping according to your window, and then set's it as the clipper for your primary surface.
- Splat
when u create and attach a clipper to a directdraw surface it will clip everything that you try to draw to that surface(it does this by default). this is the case with the above code snippet. it will compile and run, but you will just get a blank screen because the clipper clipped everything.
you have to explicity tell the clipper what area of the screen you want to be a valid drawing area. the following code shows you how to setup the clipper that will clip to the edges of the screen (you can clip any area(s) of the screen of course, but that code is a little more tedious). here's the basic approach for a 640x480 surface:
where lpddsbuffer is the dd surface u want clipped, and lpdd is your dd object...
// local variables
LPDIRECTDRAWCLIPPER lpddclipper;
LPRGNDATA cliplist;
RECT screen_rect = {0,0,640,480};
// we need to allocate some memory
cliplist = (LPRGNDATA)malloc(sizeof(RGNDATAHEADER) + sizeof(RECT));
//copy to the buffer
memcpy(cliplist->Buffer,&screen_rect,sizeof(RECT));
// set the data fields
cliplist->rdh.dwSize = sizeof(RGNDATAHEADER);
cliplist->rdh.iType = RDH_RECTANGLES;
cliplist->rdh.nCount = 1;
cliplist->rdh.nRgnSize = sizeof(RECT);
cliplist->rdh.rcBound.left= 0;
cliplist->rdh.rcBound.top = 0;
cliplist->rdh.rcBound.right = 640;
cliplist->rdh.rcBound.bottom = 480;
//now create,set,and clip!
if(lpdd->CreateClipper(NULL,&lpddclipper,NULL)!=DD_OK)
return(FALSE); // failed
if(lpddclipper->SetClipList(cliplist,0)!=DD_OK)
return(FALSE); // failed
if(lpddsbuffer->SetClipper(lpddclipper)!=DD_OK)
return(FALSE); // failed
free(cliplist);
return(TRUE); // success
as you can see, you have to declare and fill out the data fields of a RGNDATA structure and then pass it to the SetClipList() function in order to get the clipper to do what u want.
it's a pain at first, but after that it's not so bad. also, i'd put all this stuff in a sub-routine to hide all the grusome details. hence the return statements.
good luck,
don
/Niels
VirtualNext
/Niels
i use the LPDIRECTDRAWSURFACE3::Blt() function for all my blitting needs, so how could i write my own clipper without writing my own blitter? is this what you do, write your own blitter?
-DeltaRho
brad
Keep in mind that clippers do more than just clip against the edges of the screen. I can give the clipper an arbitrary number of rectangles that I want masked out, and it will correctly clip the blts to *all* of them.
This is a more general purpose solution than just clipping against the edges of the screen, so of course it will be slower.
Mason McCuskey
Spin Studios
www.spin-studios.com
