Re: [AD] Patch for rotate.c

[Sven Sandberg <svens@xxxxxxxxxx>]

David A. Capello wrote:
> This patch fix a ugly error when you rotate a sprite over a
> non-clipped bitmap 

You are right, if we are going to clip against the right edge, this is 
the correct way to do it. However...

> If you compile the test with the current Allegro version you can see:
>
>   Moving the sprite to the:
>   - left side: all work fine
>   - right side: some extra pixels appears in the left side
>   - top side and bottom side: SEG FAULT
>
> The segmentation fault is correct (because we desactivate the
> clipping), but the extra pixels that appears in left side when we
> rotate a sprite over the right side, that is bad.

As far as I understand, the behavior is undefined when drawing outside 
an unclipped bitmap, so strictly speaking I think the extra pixels are 
as OK as the SEGFAULT. In both cases, the user did an error by disabling 
clipping and then drawing outside the bitmap. Wouldn't it be better to 
insert an ASSERT(), than to allow the user to do the error?

Whether we use your patch or insert ASSERTs, the same can be done for 
top and bottom clipping too.

/Sven