Re: [Algorithms] Physics and stairs

[John B. <John.Bustard@JustAddMonsters.com>]

It all depends on what physical properties you want the player to have.
In Kungfu Chaos we had fast moving ground surfaces that could be jumped
between. In those situations you want to treat the character as an object
stuck to the surface. Each frame working out the new speed of the character
to travel with the ground and then add the velocity from the characters
movement.
To deal with stairs we used a lolipop model of the character (sphere with
ray cast down) this got the character over most bumps. But often stairs are
modelled to have each step more than half way up a character and you just
have to mark them as special areas that when hit the player climbs on top
of.
By modelling the character as an attached object moved through velocity most
of the physics interaction can be modelled correctly.
For a physics engine integration this represents a game code driven impulse
to the player to achieve the desired velocity (probably with some maximum
impulse so characters can slide and be pushed about), this impulse
represents the friction on the feet and any crazy balancing skills a
character has, they can then collide with physical objects and react
correctly.


John