Re: [pygame] Pixel Perfect collision suggestion.

[John Eriksson <john@xxxxxxxxxxxx>]

Hi,

If you're looking for a pixel perfect collision detection algorithm,
there is a project at pygame which contains an even faster one.

PixelPerfect - http://www.pygame.org/projects/9/207/

It also contains some replacements methods for spritecollide,
groupcollide and spritecollideany and an example to show how to use it.

The algorithm was used in one of the Second Pyweek Challenge winners! 

Trip on the Funny Boat - http://www.pygame.org/projects/20/235/

Best Regards
/John Eriksson

tis 2007-01-30 klockan 06:30 -0800 skrev Kamilche:
> V. Karthik Kumar wrote:
> > I happened to read the changes list a day ago. I saw the code, I thought 
> > that this change might help detect regular pp cols faster.
> > 
> > This version keeps checking pixels from the outer rectangle of the 
> > colliding area to the inner. It works considerably faster when objects 
> > are regular and convex, which is often the case.
> > 
> > This isn't a patch as such, I'd recommend people try it out and report 
> > the results and then decide.
> > 
> > Regards,
> > Karthik
> > 
> > 
> > ------------------------------------------------------------------------
> > 
> > def pp_collide(obj1,obj2):
> >     """If the function finds a collision it will return True
> >     if not it will return False.
> >     """
> >     rect1, rect2, hm1, hm2 = obj1.rect, obj2.rect, obj1.hitmask, obj2.hitmask
> >     if not rect1.colliderect(rect2):
> >         return False
> >     rect = rect1.clip(rect2)
> > 
> >     w, h, x1, y1, x2, y2 = rect.width, rect.height, rect.x-rect1.x, rect.y-rect1.y, rect.x-rect2.x, rect.y-rect2.y
> > 
> >     while w > 0 and h > 0:
> > 	for x in range(w):
> > 		if hm1[x1+x][y1] and hm2[x2+x][y2]:
> > 			return True
> > 		if hm1[x1+x][y1+h-1] and hm2[x2+x][y2+h-1]:
> > 			return True
> > 	for y in range(1, h-1):
> > 		if hm1[x1][y1+y] and hm2[x2][y2+y]:
> > 			return True
> > 		if hm1[x1+w-1][y1+y] and hm2[x2+w-1][y2+y]:
> > 			return True
> > 	w, h, x1, y1, x2, y2 = w-2, h-2, x1+1, y1+1, x2+1, y2+1
> >     return False
> 
> Is it faster than pygame's builtin rect.collidepoint method?