[ODE] Mystery Torque in the QuickStepper

[Erin Catto]

Check this link:
http://scienceworld.wolfram.com/physics/EulersEquationsofMotion.html


________________________________________
From: ode-bounces at q12.org [mailto:ode-bounces at q12.org] On Behalf Of Hunton,
Richard
Sent: Sunday, September 26, 2004 10:04 PM
To: ODE at q12.org
Subject: [ODE] Mystery Torque in the QuickStepper

Hi,
 
I have a small question about the dxQuickStepper function...
 
On line 553 (or thereabouts) of quickstep.cpp at the top of the
dxQuickStepper() function is the following code:
 
        for (i=0; i<nb; i++) {
 
                        ..........
                        ..........
                        ..........
 
                        // compute rotational force
                        dMULTIPLY0_331 (tmp, I+i*12, body[i]->avel);
                        dCROSS (body[i]->tacc, -=, body[i]->avel, tmp);
        }
 
This calculates a torque for every body in the island and subtracts it from
the body's accumulated torque. What's this torque for? Why is it being added
to each body each frame? It looks like some sort of inertial torque that is
based in the current angular velocity?
 
Cheers,

Richard Hunton