disabled physics control gets added to a physics space

[stephengold]

One of the invariants of physics controls is that if the control is disabled, the physics object cannot be "in" (added to) any physics space.

Care was taken to preserve this invariant for RigidBodyControl, CharacterControl, and VehicleControl, but not for AbstractPhysicsControl nor GhostControl.

[stephengold]

Here is a test case that demonstrates the issue:

package jme3test.bullet;

/**
 * Test case for JME issue #889: disabled physics control gets added to a
 * physics space.
 * <p>
 * If successful, no debug meshes will be visible.
 */
import com.jme3.app.SimpleApplication;
import com.jme3.bullet.BulletAppState;
import com.jme3.bullet.PhysicsSpace;
import com.jme3.bullet.collision.shapes.BoxCollisionShape;
import com.jme3.bullet.collision.shapes.CollisionShape;
import com.jme3.bullet.collision.shapes.SphereCollisionShape;
import com.jme3.bullet.control.BetterCharacterControl;
import com.jme3.bullet.control.GhostControl;
import com.jme3.bullet.control.RigidBodyControl;
import com.jme3.math.Vector3f;

public class TestIssue889 extends SimpleApplication {

    public static void main(String[] args) {
        TestIssue889 app = new TestIssue889();
        app.start();
    }

    @Override
    public void simpleInitApp() {
        flyCam.setEnabled(false);

        BulletAppState bulletAppState = new BulletAppState();
        bulletAppState.setDebugEnabled(true);
        bulletAppState.setSpeed(0f);
        stateManager.attach(bulletAppState);
        PhysicsSpace space = bulletAppState.getPhysicsSpace();

        float radius = 1f;
        CollisionShape sphere = new SphereCollisionShape(radius);
        CollisionShape box = new BoxCollisionShape(Vector3f.UNIT_XYZ);

        RigidBodyControl rbc = new RigidBodyControl(box);
        rbc.setEnabled(false);
        rbc.setPhysicsSpace(space);
        rootNode.addControl(rbc);

        BetterCharacterControl bcc = new BetterCharacterControl(radius, 4f, 1f);
        bcc.setEnabled(false);
        bcc.setPhysicsSpace(space);
        rootNode.addControl(bcc);

        GhostControl gc = new GhostControl(sphere);
        gc.setEnabled(false);
        gc.setPhysicsSpace(space);
        rootNode.addControl(gc);
    }
}