Re: [Algorithms] Colliding with stairs and sliding up them....

[R & D \(GameBrains\) <res...@ga...>]

The ramp approach works well for the character in first-person view =
because they can't see their feet, but what do you do for situations =
like a two player game where I follow you up the stairs?  Or chase an =
enemy up the stairs?
Cheers,
Brett Bibby
GameBrains

----- Original Message -----=20
From: "Neal Tringham" <nea...@nt...>
To: <gda...@li...>
Sent: Wednesday, March 13, 2002 8:19 PM
Subject: RE: [Algorithms] Colliding with stairs and sliding up them....


> David Hunt writes:
>=20
> >We cheat at stairs. We get our artists to mark the stairs as =
non-collidable
> >geometry and then replace the stair with a single invisible ramp - =
more
> work
> >for the artists - but a lot more likely to be robust + the characters =
don't
> >bounce all over the place trying to scale them. We do employ the =
levitation
> >trick to get over small things like the edges of carpets I think - =
Neal?
>=20
> Yes, this is right.  Stairs are treated as invisible ramps, but =
there's also
> a "hovercraft" system that detects whether a moving object is in =
contact
> with an underlying surface (where "underlying" is determined using the
> current gravity vector) and floats the object above the surface within =
a
> predetermined height range.
>=20
> This is done so that objects can ride smoothly over low pieces of =
geometry
> which may have vertical sides, such as carpets, but still collide =
normally
> with "real verticals" such as armchairs.
>=20
> I've actually used a similar system to this to handle stairs in the =
past -
> we cast a ray forwards in the direction of motion, and then allowed =
the
> character to "jump up" if the ray was in intersection by an amount =
hand
> tuned to be slightly greater than the height of a single step - but I =
was
> never really happy with this approach.  If you think about it, when =
people
> actually climb stairs, they're not sliding up the risers, but lifting =
their
> feet to reach the next step.
>=20
> The ramp solution is, in my view, actually more physically realistic =
than
> jumping up stair by stair, since characters in games are usually =
moving as
> single rigid objects (which can slide up a ramp) rather than fully
> articulated skeletons (which could climb stairs "properly").
>=20
> Neal Tringham (Sick Puppies / Empire Interactive)
>=20
>=20
>=20
> _______________________________________________
> GDAlgorithms-list mailing list
> GDA...@li...
> https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list
> Archives:
> http://sourceforge.net/mailarchive/forum.php?forum_id=3D6188