[Aptyp]

Here's my stupid problem - suppose I have a generic DirectDraw surface A (source), which I want to blit to generic DirectDraw surface B (destination). Because DirectDraw doesn't do auto-clip, blit call will fail if A (or rather the source rectangle defined for A) will not fit in its entirety into B.

What is known at run-time is A and B's dimensions, and a point on B to which the blit will be performed. What is required is to calculate the four rectangle points on A that encircle the area to be copied to B.

I've written the code to calculate the blit source rectangle to clip whatever parts of A don't fit into B. But I don't like it.

If anyone here has a generic clipper code that does the same thing, I'd sure love to take a look at it.

[Ninkazu]

There is a clipping class, I just don't remember its exact name. Lemme check msdn...

http://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/ddraw7/directdraw7/ddref_9j1z.asp

[janus]

Yep. If you attach a clipper, it does the work for you.

I think there's a bug in DirectDrawClipper7, if I remember, but that bug may have only affected VB. It was some sort of bug that occurred when you blitted to 0,0.

[Aptyp]

Unfortunately that only works for primary and backbuffer surfaces, since IDirectDrawClipper needs HWND reference to get the clipping information. My code is required to work with any IDirectDrawSurface7. The problem is purely mathematical, I just thought I could save myself some time by using someone else's already proven code.

[janus]