[ODE] Universal joint error and wiki query

Michael Jones m.pricejones at gmail.com
Tue Jul 25 13:15:37 MST 2006


I'm trying to set up a basic virtual creature with a universal joint for the
shoulder. I use the code:

    rShoulder = dJointCreateUniversal(world, 0);
    dJointAttach(rShoulder, body->body, rightArm->body);
    dJointSetUniversalAnchor(rShoulder, 1.75, 4.0, 0.0);
    dJointSetUniversalAxis1(rShoulder, 0.0, 1.0, 0.0);
    dJointSetUniversalAxis2(rShoulder, 0.0, 0.0, 1.0);

And it produces the following runtime warnings once at the start of the

    ODE Message 2: zero length vector in dRFrom2Axes()

    ODE Message 2: zero length vector in dRFrom2Axes()

I've visualised it and the body parts seem to be in the correct place and
the joint behaves
normally. Is this error a problem? Is there an obvious way of getting rid of
it? It makes debugging the
system a little annoying if thousands of these pop up (I'm making lots of
creatures (not in the same system))

Also, is there is reason why the dJointGetUniversalAngle1 function is not
documented in the wiki? It is in the
source code and is used in the test_joints.cpp example. I was going to add
it, but thought there might be
a valid reason for leaving it out?

Any help would be much appreciated,
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