Physics with Bullet - jMonkeyEngine 3.0 - page 423

8. We create one of the arms by placing it at the same location as that of the torso
and giving it a size of Vector3f(0.25f, 0.25f, 2f) , making it stretch
out sideways, as shown in the following code snippet:
leftArm = new Geometry("Left Arm", new Box(0.25f,
0.25f, 2f);
RigidBodyControl leftArmRigidBody = new
RigidBodyControl(new BoxCollisionShape(...), 1f);
...
leftArmRigidBody.setPhysicsLocation(new Vector3f(0,
4.25f, 0));
9. We create another SixDofJoint for it using the pivot points of Vector-
3f(0, 2.5f, 0.25f) and Vector3f(0, 0, -2.5f) , offsetting it some
distance to the side of the torso's spatial.
10. Then, we set the angular limits of the joint to Vector3f(0, 0, 0) and
Vector3f(FastMath.QUARTER_PI, 0, 0) .
11. We repeat the previous three steps to create the opposite arm, but we'll reverse the
offset values to make the arm protrude in the opposite direction of the torso.
We now have the basics done for our recipe. Running it should show the character slump-
ing to one side with the arms stretched out to the sides. Now, we can begin with balancing
by performing the following steps:
1. We create a new class called BalanceControl , extending AbstractCon-
trol .
2. It should have a SixDofJoint field called joint and a RotationalLim-
itMotor field called motorX .
3. Create a setJoint method.
4. Inside this method, after setting the joint, we also populate motorX with one of
the RotationalLimitMotor instances, as follows:
motorX = joint.getRotationalLimitMotor(0);
5. Inside the controlUpdate method, we get bodyA from the joint and store it
in PhysicsRigidBody . This is the torso:
PhysicsRigidBody bodyA = joint.getBodyA();