[ODE] more specific questions on physical movement of players..

[Mike Reinstein]

1) I understand that my friction is not good enough to stop the sphere from 
rolling, but how do I go about upping the friction? It'd be great if I don't 
have to code a lot of special cases and could build an elegant model to 
simulate movements.  Would it help if I posted in my collision callback 
implementation?

2) How do I detect the case when I'm not on the ground? Originally I thought 
I could use some call in ODE like getYVelocity(bodyID, dReal* result), but I 
cant seem to find any fnctions that allow me to get component velocity for a 
given object.

Any info would be appreciated....thanks all!


Mike

>From: "Mark Wayland" <mwayland at torus.com.au>
>To: "Mike Reinstein" <web_fella at hotmail.com>
>CC: <ode at q12.org>
>Subject: Re: [ODE] more specific questions on physical movement of 
players..
>Date: Sun, 9 May 2004 22:59:29 +1000
>
>1) Sounds like your friction model or coefficient or whatever isn't good
>enough... For your sphere, going down the stairs and not stopping 
probably
>means the sphere is only in contact with the stairs briefly, and because
>friction is only applied on contact, you aren't getting much of a 
movement
>opposing force whilst bouncing down those stairs. I handle stairs 
explicitly
>so that the player doesn't leap off the top of some stairs and land 
taking
>damage - I hate that in games. If the player jumps, I turn off the 'suck
>onto stairs' path through the code until the player has landed again.
>
>2) For starters, you only want to jump when you're on the ground, right? 
So
>that might be your first check. Secondly, as you probably can't ensure 
that
>the force will be enough to move the player off the ground in exactly 
one
>simulation cycle, you may need to 'debounce' the jump action such as 
only
>applying it when jump is transitioning from not being pressed to being
>pressed.
>
>HTH,
>Mark
>
>
>----- Original Message -----
>From: "Mike Reinstein" <web_fella at hotmail.com>
>To: <ode at q12.org>
>Sent: Sunday, May 09, 2004 2:37 PM
>Subject: [ODE] more specific questions on physical movement of players..
>
>
> > Hey all:
> >
> > I started implementing my the movement for players in the 
simulation.
> > Following the advice hplus, I represent a character as a sphere, 
and apply
> > forces to the sphere to make it move. It seems to work as I would 
expect,
> > but now I need to take away some of the physical aspects to make 
it more
> > realistic. Here are my questions:
> >
> > 1) when I release the movement and strafe keys, my moving entity 
keeps
> > moving quite a bit. I think this is due to the fact that the sum 
of forces
> > acting on the body are greater than 0, and because my friction is 
not high
> > enough...I've also noticed that my sphere cannot come to rest on a 
set of
> > stairs; it slides down the stars shortly after releasing the 
movement keys
> > which im assuming is another result of the aforementioned issue 
involving
> > friction and net forces...Am I correct? How do I go about fixing 
this?
> >
> > 2) I have implemented a jump, which basically just calls this:
> >    dBodyAddForce(bodyID, 0.0, 80.0, 0.0);
> >   This works ok, but the problem is if the user holds down the 
jump key,
>the
> > force keeps getting applied, and the user quickly starts 
ascending. How
>can
> > I fix this?
> >
> > I have other problems too, but these 2 are the most irksome...it 
seems
>like
> > my problems come from the fact that I'm applying continuous forces 
in
>trying
> > to achieve more discrete physical actions.
> > Any help woyld be appreciated!
> >
> > thanks y'all!
> >
> > neko
> >
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