Re: [pygame] extending pygame masks

["Nirav Patel" <olpc@xxxxxxxxxxxxxx>]

Mike,

I'm not sure if this is what you mean, but the Mask module has a
function in SVN called Mask.overlap_mask, which returns a mask of the
overlapping pixels between two masks by an offset.

The internals of most of the bitmask stuff is exposed in bitmask.h.
It could be useful to move the defines and typedef from mask.c to
there.  I think the reason it wasn't is that what's in bitmask.h
currently is purely C, while the typedef has a PyObject_HEAD in it.
Alternately, if you're making an external module, you could just
import bitmask.h and copy the typedef and defines into your file.

Nirav

On Tue, Oct 14, 2008 at 9:11 AM, Michael George <mdgeorge@xxxxxxxxxxxxxx> wrote:
> hello,
>
> I've been working on some code that generates what I've been calling a
> "hitmask", namely a mask with the (x,y) bit set if placing one mask on
> another offset by (x,y) would cause a collision.  It's part of a slick
> algorithm I'm working on for drag-and-drop collision response.  I've
> implemented it in C against the bitmask api.  I have n questions:
>
> 1. Is there any interest in putting this in pygame?  I suspect no, because
> it's only useful for situations where you may freely drag oddly-shaped
> objects around but need to avoid collisions between them.  It would be good
> for things like map editors.  However if there is interest, I'd be happy to
> contribute it.
>
> 2. If not, I'd like to avoid shipping a modified pygame with my game.  Is it
> possible for me to build and ship extensions that link against pygame
> internals (really just the bitmask stuff, and maybe rects at some point)?  I
> haven't dug into the python/C boundary too much, although glancing over the
> pygame source it doesn't seem too bad.  Can someone point me in the right
> direction?
>
> 3. If I do build my code separately, it currently looks impossible to
> actually get at the internals of a PyMaskObject without doing something
> hacky.  In particular, the data structure and the PyMask_AsBitmap macro are
> only defined in mask.c, rather than in a separate header file.  Is it
> reasonable for you to move that into pygame.h, or is it hidden for a reason?
>
>
> ...where n = 3.
>
> Thanks!
>
> --Mike
>