[ODE] ODE in FPS (ground feet)

[Konstantin Voloshin]

(this is reply to http://q12.org/pipermail/ode/2003-September/010001.html)

Hi,

> -How can you tell if the player's feet are "on the ground"?  I am thinking
> of adding a sphere at the bottom of the cylinder that gets a flag set upon
> collision.  If that flag is true then the player is allowed to move/jump.
> The player would be a composite of cylinder/sphere.

There was a little problem I've encountered in implementing something
like you're suggesting. Considerable ammount of frames reported no
collision with the ground when player was just moving horizontally on
horizontal surface (triangle set actually). Gravity was present :)

It can be avoided by manually lowering a little the penetration depth of
contact-joints, attached to player body (perhaps, even skipping contacts
with depth less than certain small value)

SY, VolK