rotating composite bodies

[blarmee]

Hi - How do you rotate composite bodies?  I have one that is made up of a number of GeomTransforms, and I'm trying to rotate it around its Z-axis at a particular angular velocity, but I'm having no luck.

I've tried using the setAngularVel() method on the body and I've also tried using AMotors, but the body just doesn't rotate.

[ewills]

How about applying a torque about the z-axis?

[blarmee]

That doesn't seem to have any effect either.

Here is the code that I'm using.  Does it look right?

1   2   3   4   5   6   7   8   9   10   11   12   13   14   15   16   17   18   19   20   21   22   23   24   25   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40   41   42

this.sideWalls = new Body(world);     this.sideWalls.setGravityMode(0);     this.groundGeomB = new GeomBox((float)this.bounds.getWidth(), 10f, 50f);     this.groundGeomT = new GeomBox((float)this.bounds.getWidth(), 10f, 50f);     this.groundGeomL = new GeomBox(10f, (float)this.bounds.getHeight(), 50f);     this.groundGeomR = new GeomBox(10f, (float)this.bounds.getHeight(), 50f);     this.groundGeomBE = new GeomTransform("t1");     this.groundGeomTE = new GeomTransform("t2");     this.groundGeomLE = new GeomTransform("t3");     this.groundGeomRE = new GeomTransform("t4");     this.groundGeomBE.setEncapsulatedGeom(this.groundGeomB);     this.groundGeomTE.setEncapsulatedGeom(this.groundGeomT);     this.groundGeomLE.setEncapsulatedGeom(this.groundGeomL);     this.groundGeomRE.setEncapsulatedGeom(this.groundGeomR);     this.sideWalls.addGeom(this.groundGeomBE);     this.sideWalls.addGeom(this.groundGeomTE);     this.sideWalls.addGeom(this.groundGeomLE);     this.sideWalls.addGeom(this.groundGeomRE);     this.groundGeomB.setPosition(0f, (float)(-1 * this.bounds.getHeight()/2 - 5), 0f);     this.groundGeomT.setPosition(0f, (float)(this.bounds.getHeight() + 5), 0f);     this.groundGeomL.setPosition((float)(-1 * this.bounds.getWidth()/2 - 5), 0f, 0f);     this.groundGeomR.setPosition((float)(this.bounds.getWidth()/2 + 5), 0f, 0f);     this.geomIDs.add(this.groundGeomBE.getNativeAddr());     this.geomIDs.add(this.groundGeomLE.getNativeAddr());     this.geomIDs.add(this.groundGeomRE.getNativeAddr());     this.geomIDs.add(this.groundGeomTE.getNativeAddr());     this.sideWalls.adjustMass(10f);     this.sideWalls.setPosition((float)(this.bounds.getWidth()/2 + this.bounds.getX()),                          (float)(this.bounds.getHeight()/2 + this.bounds.getY()),                          0f);     space.addBodyGeoms(this.sideWalls);     this.sideWalls.setAngularVel(50, 0, 0);     this.sideWalls.addRelTorque(5000,0,5000);

Games published by our own members! Check 'em out!

[ewills]

This looks right... The body should rotate regardless of the geoms attached to it.  Are you sure that world.step() or world.quickStep() is being called iteratively?

edit:
Is the Body in contact with any other geoms that are keeping it from turning?

[blarmee]

It seems to be fixed now.  I had to manually set an inertial tensor and center of mass with setMassParameters.  I also changed the ordering around a bit.  Not sure why this was necessary though.

Thanks for the help though :P

[ewills]

Ah yes.  A Body with transformed geoms does not seem to function correctly (at least correctly determine collisions in my experience) unless initial inertial parameters are set.