[ODE] A slider joint to bond an axis-aligned body with a rigid bodygroup?

[Jon Watte]

That sounds like an interesting project! Here's what I can think 
of (having not actually gone that far in my character 
implementation):

As you say, you need a slider plus a ball joint. Because you 
can't chain joints, you have to play some tricks, such as adding 
an intermediate body of small (but not negligible) mass to 
attach the slider to, then attach the ball joint between that 
intermediate body and the actual hip/pelvis body. Taking the hip 
mass and dividing it by two might work.

Also, the rag doll may have a wierd center of mass if the body 
for the player capsule is very heavy -- you might want to reduce 
its mass substantially while doing the rag-dolling, and kicking 
it back up when you're done.

Cheers,

			/ h+


-----Original Message-----
From: ode-bounces at q12.org [mailto:ode-bounces at q12.org]On Behalf Of Megan
Fox
Sent: Wednesday, October 13, 2004 12:32 PM
To: ode at q12.org
Subject: [ODE] A slider joint to bond an axis-aligned body with a rigid
bodygroup?


Let me try to explain exactly what I have: I have a player body which
is forced to remain upright via direct control of torque and
orientation (I know, I know, it isn't "fancy", but it works perfectly
and never requires tweaking).  I need to join this to the root of a
collection of jointed rigid bodies via a slider joint.

This slider joint must remain at the same alignment as the player
body, but the root body of the collection attached at the other end
can rotate about the point of the attachment (and of course the joints
within the collection can bend and flex and whatever else they need to
do).

How would I go about implementing this?  I guess what I need is sort
of like a suspension + axle, but not quite - replace the axle with a
balljoint and you're getting closer, but even then setting the
orientation of the "top" body would seemingly break the construct?