(I thought I should send my response to the entire list as well...sorry for the duplicate e-mail Ethan)
On Jun 19, 2007, at 2:24 PM, Ethan Glasser-Camp wrote: > How did you build chains using ODE? (This is personal curiosity; the > most effective chains I've been able to build have been hinge joint + > slider, but that's only in 2D.) Thanks Ethan. I basically based my chains on the examples that come with the ODE distribution (specifically "ode/test/test_chain1.c"). I've included my (not-very-well commented) code below. I model each chain as a GeomCapsule and attach them to each other using ball joints. I'm able to get 20 links in the chain without a problem, and with expected bending behavior (screenshot: http://zeitkunst.org/ media/images/chains.png). Applying all types of forces to the chain gives reasonably expected movement and bending of the chains. > I'm not sure but this looks like you should be using some kind of > motor instead of computing forces like this. Does anyone have good references for using motors? I've looked a bit at the examples on the PyODE website, but would appreciate other suggestions. Thanks, nick xPosition, yPosition, zPosition = initialPosition for linkNumber in range(self.numLinks): link = ode.Body(self.world) M = ode.Mass() M.setBox(density, size[0], size[1], size[2]) M.adjust(0.5) link.setMass(M) # offset the start position by half of the y dimension k = (linkNumber * size[1]) + (initialPosition[1] + size [1]/2.0) link.setPosition((initialPosition[0], k, initialPosition [2])) link.currentPosition = (initialPosition[0], k, initialPosition[2]) yPosition += size[1] - 0.1 self.bodies.append(link) geom = ode.GeomCapsule(self.space, radius = self.size[1]/ 2.0, length=self.size[0]) geom.setBody(link) self.geom.append(geom) self.bodyHoldPosition = array((initialPosition[0], k, initialPosition[2])) # create joint with creature joint = ode.BallJoint(self.world) joint.attach(self.bodies[0], self.creatureBody) joint.setAnchor((initialPosition[0], initialPosition[1] - size[1]/2.0, initialPosition[2])) self.joints.append(joint) for linkNumber in range(self.numLinks - 1): joint = ode.BallJoint(self.world) joint.attach(self.bodies[linkNumber], self.bodies [linkNumber + 1]) k = (linkNumber + 1) * size[1] + initialPosition[1] - size[1]/2.0 joint.setAnchor((initialPosition[0], k, initialPosition [2])) self.joints.append(joint) ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Pyode-user mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/pyode-user
