[SOLVED] Sticky CharacterControl collision

Troubleshooting physics
1

My CharacterControl is moving across a smooth surface with no bumps or niches. For some reason, I can only move a few inches before stopping as if hitting an object. I have to jump over whatever it is. It moves just fine in the air.

My Code 
private final float jumpVel = 20, fallForce = 30, mass = 70f, height = 10;
CapsuleCollisionShape capsule = new CapsuleCollisionShape(1f, height);
private CharacterControl guy;
Geometry body;
private final Node guyNode = new Node("player node");
...
protected void build(AssetManager manager) {
	guy = new CharacterControl(capsule, 0);
	guy.setJumpSpeed(jumpVel);
	guy.setFallSpeed(fallForce);
	guy.setPhysicsLocation(pos);
	guy.setGravity(new Vector3f(0, -20, 0));
	body = new Geometry("body", new Box(1, height*0.5f, 1));
	body.setLocalTranslation(pos);
	Material mat = new Material(manager, "Common/MatDefs/Light/Lighting.j3md");
	mat.setBoolean("UseMaterialColors", true);
	mat.setColor("Diffuse", ColorRGBA.Blue);
	body.setMaterial(mat);
	body.addControl(guy);
	guyNode.attachChild(body);
}
...
protected void move(Camera cam) {
	Vector3f camDir = cam.getDirection().multLocal(0.5f);
	Vector3f camLeft = cam.getLeft().multLocal(0.2f);
	Vector3f walkDirect = new Vector3f(0, 0, 0);
	if (up) walkDirect.addLocal(camDir.x, 0, camDir.z);
	if (down) walkDirect.addLocal(-camDir.x, 0, -camDir.z);
	if (left) walkDirect.addLocal(camLeft);
	if (right) walkDirect.addLocal(camLeft.negate());
	guy.setWalkDirection(walkDirect);
}

The collision box for the player doesn’t seem to go into the ground anyway (hard to tell tho). :confused:

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2

I was having several problems like that with CapsuleCollisionShape , one of them was the object being flipped & rolled inside the capsule enclosure as if i were doing experiments on a hamster ,LOL,

i think that basically happens if you have a radius below a particular offset or the height is larger than radius.

try BoxCollisionShape for box or tall objects , use CollisionShapeFactory.createBoxShape(shape:Spatial); for regular box shape. & try this if you need full collision mesh CollisionShapeFactory.createDynamicMeshShape(shape:Spatial) but its cpu intense & very accurate .

Check CollisionShapeFactory class :

https://javadoc.jmonkeyengine.org/v3.3.2-stable/index.html

1 Like
3

if its normal Character control adjust the step size, BCC also suffers this but there is no step size adjustment for that

4

In case you haven’t solved this issue yet, I suggest comparing your app with one of the jme3-examples apps that use CharacterControl:

If those apps work for you, focus on what your app does differently.

5

I’m still having the problem.

I tried running those examples, all of them have some these strange bugs for me.

  • HelloCollision was stopped with a null pointer exception (probably due to missing assets).
  • HelloTerrainCollision had the gravity flipped so I had to constantly jump in order to stay down.
  • TestPhysicsCharacter had the gravity flipped sideways.
  • TestWalkingCharacter also had the same problem.
  • TestBetterCharacter was better, but it still had sticky collisions on the side of blocks.

It almost seems that the default gravity direction is sideways, because when I do not specifically set gravity for my CharacterControl, I end up falling sideways.

Maybe CharacterControl is just messed up for me?

1 Like
6

The sideways gravity symptoms you describe match issue 910, which affects jme3-bullet in v3.2. Please upgrade to JME v3.3 and/or use Minie or jme3-jbullet.

By the way, TestBetterCharacter doesn’t actually use CharacterControl.

1 Like
7

What is it? I can’t find it in the docs.

1 Like
8

jme3-jbullet is a physics library included in JMonkeyEngine that’s compatible with jme3-bullet, only written entirely in Java. (jme3-bullet uses JMI to access C++ code.)