Physics with Bullet - jMonkeyEngine 3.0 - page 429

How to do it...
We're going to start by creating two methods that will help us add new bridge segments to
the game:
1. We define a method called createSegment that takes a Vector3f parameter
called location as the input.
2. The first thing we do is set the z value of location to 0 . This is because we're
making a 2D game.
3. Then, we create a new RigidBodyControl instance called newSegment . We
add SphereCollisionShape to it and then add newSegment to physic-
sSpace . It's important that it has some mass. This can be implemented as follows:
RigidBodyControl newSegment = new RigidBodyControl(new
SphereCollisionShape(1f), 5);
bulletAppState.getPhysicsSpace().add(newSegment);
4. Now, we create a Geometry instance based on a Sphere shape with the same
radius as RigidBodyControl . We will use this as a target for mouse clicks.
5. The Geometry object needs modelBound for which we'll use Boundin-
gSphere . The radius may be bigger than RigidBodyControl .
6. The RigidBodyControl object is added to Geometry as a control and we use
the setPhysicsLocation method to move it to the to the supplied location, as
follows:
geometry.addControl(newSegment);
newSegment.setPhysicsLocation(location);
7. The Geometry object is then added to the segments list we defined earlier and
then it is attached to rootNode .
8. If selectedSegment is not null, we will call a method we will define next:
createJoint(selectedJoint, newSegment);
9. Lastly, in the createJoint method, we set selectedSegment to be
newSegment .
10. Now, we can define the createJoint method. It takes two RigidBodyCon-
trol parameters as the input, as shown in the following code: