[ODE] Mystery Torque in the QuickStepper

Erin Catto erincatto at sbcglobal.net
Sun Sep 26 23:02:49 MST 2004

Check this link:

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

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?

Richard Hunton

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