Re: [pygame] Bitmask Collision Response

[Michael George <mdgeorge@xxxxxxxxxxxxxx>]

One option I've been investigating is the use of convolutions for 
bitmask collision response.  I've been using it for drag-and-drop 
collision response, but you might find it useful for other kinds of 
response as well.

The way it works is as follows: if I have an object that's moving 
through an environment, then convolving the object's mask with the 
environment's mask yields a mask with the corresponding bit set if 
placing the object at that location would cause a collision.  For drag 
and drop I form the convolution, and then place the object at the 
closest point to the mouse that has the bit cleared.

You can take a look at some code at 
http://pen.svn.sourceforge.net/viewvc/pen/src/ (see drag.py, 
demos/dragdemo.py, and maskutils.c).  unfortunately it's been 
bit-rotting for a bit, so it may not work out of the box.

Hope it helps!

--Mike

pymike wrote:
> Howdy,
>
> I'm currently working on a project that requires bitmask collisions. I 
> know how to /detect/ collisions, but it's response that has me 
> stumped. I've been googling, and all I can find is detection - nil on 
> response. Can anyone help?
>
> I fear I may have to resort to a physics engine, though I'd very much 
> like to keep it pure pygame.
>
> Ciaozorz
>
> --
> - pymike