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Creating a offscreen surface gives error!

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or could the problem be:

primsurf->BltFast(pos_x, pos_y, bitmap, NULL, DDBLTFAST_NOCOLORKEY | DDBLTFAST_WAIT);

that worked before!

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Are you clearing the memory for bigdesc before filling it?

If not, do this one of the following
ZeroMemory(&bigdesc, sizeof(bigdesc));

or memset(&bigdesc, 0, sizeof(bigdesc));

Hope this helps. If not, please give us the error code in order to help us help you.

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Ok, that's a shame!

Is there a way to blit images partially off the screen without using clippers?

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All of the error codes for DirectDraw are defined in ddraw.h. You could write a simple class that switches the DDEER_SOMEERROR value and returns a string you could display in a message box.

I've heard other folks mention that with DX7, there is a function called D3DGetErrorCode or something like that, that you can use to do pretty much what I just described. I'm not sure though, i wrote my own class back when DX3 came out so I've always stuck with that.

As for bliting without clipping, I wouldn't recommend it. It'll crash on most computers (although I have seen it run on one or two). If you don't want to use DirectDrawClipper, you can just write your own. It's not to hard, and you should be able to find lots of tutorials on how to do it on the net.

Hope this helped, if not let me know, and I'll try to be more specific.

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Well, thanks for the help. I think I can come up with something. As for the clippers I will try to use them, it can't be that hard. But that switch statement. How should it look like, and where should it be placed?
Again, thanks for the help!

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Stark,

for blitting images that are partially offscreen, couldn't ZomeonE use the 'Blt' function instead of using BltFast and DirectDrawClipper? I'm still wet behind the ears for DX programming so I don't really know what works best, but it might give him the functionality he's after.

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Yup. Actually, he could use whichever Blit function (BltFast, or Blt) he wanted to and use the built in DirectDrawClipper or a custom built one that basically would shrink his source rectangle to one that would fit onto his destination surface.

As for the DirectDraw error class. Here's an excerpt from mine:


void TranslateError(HRESULT hError, char *szMesg)
{
switch(hError)
{
case DD_OK:
strcpy(szMesg, "No problem!");
break;
case DDERR_ALREADYINITIALIZED:
strcpy(szMesg, "The object has already been initialized.");
break;
case DDERR_BLTFASTCANTCLIP:
strcpy(szMesg, "A DirectDrawClipper object is attached to a source surface that has passed into a call to the IDirectDrawSurface3::BltFast method.");
break;
case DDERR_CANNOTATTACHSURFACE:
strcpy(szMesg, "A surface cannot be attached to another requested surface.");
break;
....
..
.
}

** An important assumption for this to work; szMesg is large enough to hold the message. You should put some error checking in here.

Anyways, the error messages were more or less just copied and pasted from the DX help files and formated. All, in all, it took me about an hour or two to complete the class and it's proved it's usefulness many times over.

Hopefully this helped ya out, otherwise, let me know...

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Clipping isn't really needed. Instead of drawing the whole src image (0, 0 to IMAGE_W, IMAGE_H) to the screen at -10, -10, try drawing to 0, 0 from the src image at 10, 10 to IMAGE_W, IMAGE_H. In other words: do the clipping yourself. This would end up being faster, anyways.

------------------
- mallen22@concentric.net
- http://members.tripod.com/mxf_entertainment/

[This message has been edited by Matthew Allen (edited December 07, 1999).]

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I'm trying to create an offscreen surface with direct draw, but it returns a error. Whats wrong?

bigdesc.dwSize = sizeof(bigdesc);
bigdesc.dwFlags = DDSD_CAPS | DDSD_HEIGHT | DDSD_WIDTH;
bigdesc.ddsCaps.dwCaps = DDSCAPS_OFFSCREENPLAIN;
bigdesc.dwWidth = SCREEN_WIDTH + (TILE_WIDTH * 2);
bigdesc.dwHeight = SCREEN_HEIGHT + (TILE_HEIGHT * 2);
if(ddraw->CreateSurface(&bigdesc, &bigsurf, NULL) != DD_OK)
return(1);

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