Hello again,
i just wanted to contribute this to the community. It's a drop in replacement of the PhysicsGameState which allows to render the physics debug overlay. Additionally it gives you a 'PAUSE' button for the physics simulation. (i really like the effect of being able to fly around in a frozen scene 
). Anyways … here it is:
package de.fhaust.cc;
import java.util.logging.Logger;
import com.jme.input.KeyBindingManager;
import com.jme.input.KeyInput;
import com.jme.system.DisplaySystem;
import com.jmex.game.state.BasicGameState;
import com.jmex.physics.PhysicsDebugger;
import com.jmex.physics.PhysicsSpace;
/**
* A dropin replacement to PhysicsGameState that allows debug graphics to be displayed
* and stopping of the physics simulation.
* Rendering is continued with the physics stopped.
*
* Key Mapping:
* O - pauses/unpauses the physics simulation
* V - toggles the physics debug overlay
*
* @author Florian Hofmann (florian@fhaust.de)
*
*/
public class DebugPhysicsGameState extends BasicGameState {
private PhysicsSpace physics;
protected boolean showPhysics = false;
protected boolean simulationPaused = false;
/** Strings for commands */
private static final String DEBUG_COMMAND = "toggle_physics_debug";
private static final String PAUSE_COMMAND = "toggle_physics_pause";
/** private logger */
private static final Logger log = Logger
.getLogger(DebugPhysicsGameState.class.getName());
/**
* Creates a new DebugPhysicsGamestate
* handles input by default
* @param name
*/
public DebugPhysicsGameState(String name) {
this(name, true);
physics = PhysicsSpace.create();
}
/**
* Creates a new DebugPhysicsGamestate
* @param name
* @param handleInput should we handle input?
*/
public DebugPhysicsGameState(String name, boolean handleInput) {
super(name);
/** create key bindings if input handling is true */
if (handleInput) {
initKeyBindings();
}
}
private void initKeyBindings() {
/** Assign key V to action "toggle_physics_debug". */
KeyBindingManager.getKeyBindingManager().set(DEBUG_COMMAND,
KeyInput.KEY_V);
/** Assign key O to action "toggle_physics_pause". */
KeyBindingManager.getKeyBindingManager().set(PAUSE_COMMAND,
KeyInput.KEY_O);
log.info("press V to display physic debug graphicsn" +
"press O to pause the simulation");
}
public void update(float tpf) {
super.update(tpf);
/** Run simulation if it is not paused */
if (!simulationPaused)
physics.update(tpf);
/**
* If toggle_physics_debug is a valid command (via key V), change
* physics.
*/
if (KeyBindingManager.getKeyBindingManager().isValidCommand(
DEBUG_COMMAND, false)) {
showPhysics = !showPhysics;
}
/**
* If toggle_physics_pause is a valid command (via key V), change
* physics.
*/
if (KeyBindingManager.getKeyBindingManager().isValidCommand(
PAUSE_COMMAND, false)) {
simulationPaused = !simulationPaused;
}
}
@Override
public void render(float tpf) {
super.render(tpf);
/** display debug graphics for physics */
if (showPhysics)
PhysicsDebugger.drawPhysics(physics, DisplaySystem
.getDisplaySystem().getRenderer());
}
/**
* return the physics space
* @return
*/
public PhysicsSpace getPhysicsSpace() {
return physics;
}
public void pauseSimulation(boolean simulationPaused) {
this.simulationPaused = simulationPaused;
}
public void showPhysics(boolean showPhysics) {
this.showPhysics = showPhysics;
}
}
As you can see it doesn't do much so i'd consider it as quite stable. Hopefully someone could integrate it into the repository with a appropriate license section (and with a spellchecking of the comments ;) ).
In related news:
I have a big problem with the PhysicsDebugger: as long as the simulation is running all joints and forces are shown in the world origin (0,0,0) ... as soon as i stop it they snap right back where they belong. You can see this behavior in the attached picture. As far as i know the overlay works fine in SimpleGame and other Tests ... so i think this is related somehow to StandardGame
So far ...
Goliat
[edit:] added setter methods for showPhysics and pausePhysics