Gravity not working for me

Troubleshooting General Help
1

Hi,



I have written a program where I place a ball on a floor, and I have used classes like RigidBodyControl and BulletAppState to get physics simulation.



If I have only ball and not floor then ball just free falls which is expected. And if I program such that floor is tilted then again ball just rolls down the slope.

But if I program for user input so that on pressing a key the floor tilts then I am not getting this rolling effect, ball just remains where it is.

Any idea why thismay be happening.



Manish

2

when i saw the title i was like “superman much?”



do [java]floor.getControl(RigidBodyControl.class).setKinematic(true);[/java] and move it with rotate(), and see what happens

3

Add

[java]

bulletAppState.getPhysicsSpace().enableDebug(assetManager);

[/java]

to your simpleInitApp and it will show you what the real physics object is



My guess is your moving the mesh and the physics object is staying in the same place.

4

floor.getControl(RigidBodyControl.class).setKinematic(true);



didn’t work.



bulletAppState.getPhysicsSpace().enableDebug(assetManager)



crashes for me.

5

Do you “setApplyPhysicsLocal(true)” somewhere? I had the effect you describe when doing that (just to test what it does).

6

no i didn’t…so i did it, but still no change…



here is my code



bulletAppState = new BulletAppState();

stateManager.attach(bulletAppState);

sphere = new Sphere(32, 32, 0.1f, true, false);

Geometry sphere_geo = new Geometry(“Sphere”,sphere);

Material sphere_mat = new Material(assetManager, “Common/MatDefs/Misc/Unshaded.j3md”);

sphere_mat.setColor(“Color”, ColorRGBA.Gray);

sphere_geo.setMaterial(sphere_mat);

rootNode.attachChild(sphere_geo);

sphere_geo.move(0,.1f,0);

ball_phy = new RigidBodyControl(1f);

sphere_geo.addControl(ball_phy);

bulletAppState.getPhysicsSpace().add(ball_phy);



floor = new Box(Vector3f.ZERO,2f,0.1f,2f);

floor_geo = new Geometry(“Floor”,floor);

Material floor_mat = new Material(assetManager, “Common/MatDefs/Misc/Unshaded.j3md”);

floor_mat.setColor(“Color”, ColorRGBA.Green);

floor_geo.setMaterial(floor_mat);

rootNode.attachChild(floor_geo);

floor_phy = new RigidBodyControl(0.0f);

floor_geo.addControl(floor_phy);

if(floor_geo.getControl(RigidBodyControl.class)!=null){

((RigidBodyControl)floor_geo.getControl(RigidBodyControl.class)).setKinematicSpatial(true);

((RigidBodyControl)floor_geo.getControl(RigidBodyControl.class)).setApplyPhysicsLocal(true);

}



bulletAppState.getPhysicsSpace().add(floor_phy);

7

anyone having any idea?

8

i set mine to kinematic, and rotate my floor with normal .rotate() methods, and it works fine

9

is location of code an issue…above code is in simpleInitApp

and in onAction i have placed



floor_geo.rotate(0,0,FastMath.HALF_PI/8);

10

use setKinematic(true) not setKinematicSpatial



i use:



[java]

CollisionShape shape = CollisionShapeFactory.createMeshShape(tiltingDome);

RigidBodyControl control = new RigidBodyControl(shape, 0);

control.setFriction(5f);



tiltingDome.addControl(control);

tiltingDome.getControl(RigidBodyControl.class).setKinematic(true);

bulletAppStateScreen.getPhysicsSpace().add(tiltingDome);

rootNodeScreen.attachChild(tiltingDome);



[/java]



and in onAnalog



[java] tiltingDome.rotate(0, 0, value); [/java]

1 Like
11

hi wezrule…it worked.

thanks a lot buddy.