Re: [pygame] Directional collision detection.

[B W <stabbingfinger@xxxxxxxxx>]

I did the following, which adequately fit my needs. Unfortunately
there is some ambiguity to overcome. For example, if one rect is
moving at speed 5,5 and the other at -5,-5 their corners will collide.
In this case two sides are in contact and you must quantify it in
program code to decide which way they should rebound.

class Struct(object):
    def __init__(self, **entries):
        self.__dict__.update(entries)

def collide_edges(r, other):
    """Detect the edges of rectangle r that collide with rectangle
    other. Returns an ad hoc object with boolean attributes left,
    right, top, and bottom whose values indicate whether that side
    collided."""
    Rect = pygame.Rect
    side = Struct(left=False, right=False, top=False, bottom=False)
    left=Rect(r.left, r.top+1, 1, r.height-2)
    right=Rect(r.right, r.top+1, 1, r.height-2)
    top=Rect(r.left+1, r.top, r.width-2, 1)
    bottom=Rect(r.left+1, r.bottom, r.width-2, 1)
    if left.colliderect(other):
        side.left = True
    if right.colliderect(other):
        side.right = True
    if bottom.colliderect(other):
        side.bottom = True
    if top.colliderect(other):
        side.top = True
    return side

if __name__ == '__main__':
    pygame.init()
    r1 = pygame.Rect(1,1,10,10)
    r2 = pygame.Rect(9,9,10,10)
    edges = collide_edges(r1, r2)
    print '%s: %s' % ('left',edges.left)
    print '%s: %s' % ('right',edges.right)
    print '%s: %s' % ('top',edges.top)
    print '%s: %s' % ('bottom',edges.bottom)

fin

On Sun, Feb 22, 2009 at 1:21 PM, Daniel Mateos <daniel@xxxxxxxxx> wrote:
> Hey,
>
> Can anyone suggest a good way to do collision detection between two
> rects in a way that i can also get the side of the rect that the
> collision was detected on.
>
> --
> Daniel Mateos
> http://daniel.mateos.cc
>
>