Types of forces
Panda3D provides two types of forces that you can apply to an object.
LinearVectorForce treats the object as a point mass. It applies an
acceleration in Newtons to the center of mass of the object it was added to. The
direction of this force is relative to the orientation of the
LinearVectorForce was applied to.
LinearVectorForce treats the object as a point mass, it is not
possible to apply a rotation of any kind to your object. For rotational
lvf = LinearVectorForce(1, 0, 0) # Push 1 newton in the positive-x direction forceNode.addForce(lvf) # Determine coordinate space of this force node actorNode.getPhysical(0).addLinearForce(lvf) # Add the force to the object
AngularVectorForce applies a torque to the object it is attached to. The
acceleration is in Newtons, and
AngularVectorForce may be treated in much
the same way as
LinearVectorForce. There are, however, some minor
differences that that should be taken into account.
AngularVectorForce does not have a
.setDependantMass(). The reason for
this is simple: mass must be used in the torque calculations. As such, you
will want to make sure your forces are sufficiently small or your masses are
sufficiently large to keep your rotational velocity sane.
avf = AngularVectorForce(1, 0, 0) # Spin around the positive-x axis forceNode.addForce(avf) # Determine which positive-x axis we use for calculation actorNode.getPhysical(0).addAngularForce(avf) # Add the force to the object
One additional caveat with
AngularVectorForce: Angular forces will not be
processed on your object until an
AngularIntegrator is added to the
from panda3d.physics import AngularEulerIntegrator # Instantiate an AngleIntegrator() angleInt = AngularEulerIntegrator() # Attach the AngleIntegrator to the PhysicsManager base.physicsMgr.attachAngularIntegrator(angleInt)
Editor’s Note: Each type of force should be given it’s own page with much more in depth examples, and perhaps a small sample program.