Block rigidbody rotation

Troubleshooting physics
1

Hi, i want to block a rigidbody physic rotation, i tryed to set the quaternion but the y location of the rigidbody started to go up…

2

What does this mean?

Why did you delete the post that actually had the information we’d need to help you?

Hint: if you are calling quaterion.set(x, y, z, w) then you are already doing something wrong. Probably setting total nonsense to the quaternion.

2 Likes
3

i’m setting the rigidbody.setphysicRotation(quaternion), make quaternion using a matrice like that

private float [][] rotPos = {
            {1.0f, 0.0f ,0.0f},
            {0.0f, 1.0f ,0.0f},
            {0.0f, 0.0f ,1.0f}
        };

(sorry for eng, i’m italian)

4

Show all the code.

1 Like
5 
private void blockRotation(){
    
    Quaternion qt = this.getControl(RigidBodyControl.class).getPhysicsRotation();
    qt.set(0f, 0f, 0f, 1f);
    this.getControl(RigidBodyControl.class).setPhysicsRotation(qt);
}

this method is called with simpleUpdate (this is extended to Node)

6

Every update, you zero out all rotation but any rotational acceleration has to go somewhere.

We still don’t see enough code.

Put together a simple test case that fully shows the problem.

7

public class Player extends Node implements ActionListener, AnalogListener{

RigidBodyControl rb;
InputManager inputManager;

Geometry playerGeom;

private Vector3f startPos;



private float [][] rotPos = {
            {1.0f, 0.0f ,0.0f},
            {0.0f, 1.0f ,0.0f},
            {0.0f, 0.0f ,1.0f}
        };

FpsCam cam;

float playerWalkSpeed = 5.0f;
public Player(AssetManager assetManager, InputManager inputManager, FpsCam cam){
    this.cam = cam;
    startPos = new Vector3f(0f,2f,0f);
    
    this.inputManager = inputManager;
    
    setPlayerInternal(assetManager);

    this.attachChild(playerGeom);
    
    initKeys();
}

private void setPlayerInternal(AssetManager assetManager){
    Material mat = new Material(assetManager,"Common/MatDefs/Misc/Unshaded.j3md");
    playerGeom = new Geometry("player", new Box(0.5f,1f,0.5f));
    playerGeom.setMaterial(mat);
    
    playerGeom.setLocalTranslation(startPos);
    
    CollisionShape shape = CollisionShapeFactory.createBoxShape(playerGeom);
    rb = new RigidBodyControl(shape,0.001f);
    rb.setGravity(new Vector3f(0f,-1f,0f));
    rb.setPhysicsLocation(startPos);
    rb.setAngularDamping(1f);
    rb.setFriction(1f);
    
    //rb.setPhysicsRotation(new Quaternion(0f,0f,0f,0f));
    this.addControl(rb);
    playerGeom.addControl(rb);
    
    
    
}

private void blockRotation(){
    
    Quaternion qt = this.getControl(RigidBodyControl.class).getPhysicsRotation();
    qt.set(0f, 0f, 0f, 1f);
    this.getControl(RigidBodyControl.class).setPhysicsRotation(qt);
}

public void update(float tpf){
    cam.setLocalPosition(new Vector3f(playerGeom.getLocalTranslation().x -2f,playerGeom.getLocalTranslation().y + 1.3f,playerGeom.getLocalTranslation().z));
    //this.getControl(RigidBodyControl.class).setPhysicsRotation(Quaternion.IDENTITY);
    blockRotation();
    
}

//update methods
@Override
public void onAction(String action, boolean isPresed, float tpf) {
    switch(action){
        case "jump":
            this.getControl(RigidBodyControl.class).setLinearVelocity(new Vector3f(
                    this.getControl(RigidBodyControl.class).getLinearVelocity().x,
                    5f,
                    this.getControl(RigidBodyControl.class).getLinearVelocity().z              
            ));
            break;
    }
    
    //this.getControl(RigidBodyControl.class).applyCentralForce(new Vector3f(cam.getCam().getDirection().x * playerWalkSpeed,0f,cam.getCam().getDirection().z*playerWalkSpeed));
}

private void initKeys(){
    inputManager.addMapping("up", new KeyTrigger(KeyInput.KEY_W));
    inputManager.addMapping("down", new KeyTrigger(KeyInput.KEY_S));
    inputManager.addMapping("left", new KeyTrigger(KeyInput.KEY_A));
    inputManager.addMapping("right", new KeyTrigger(KeyInput.KEY_D));
    inputManager.addMapping("jump", new KeyTrigger(KeyInput.KEY_SPACE));
    
    
    inputManager.addListener(this, "up");
    inputManager.addListener(this, "down");
    inputManager.addListener(this, "left");
    inputManager.addListener(this, "jump");
}

@Override
public void onAnalog(String action, float arg1, float arg2) {
    switch(action){
        case "up":
        this.getControl(RigidBodyControl.class).setLinearVelocity(new Vector3f(
                    cam.getCam().getDirection().x*playerWalkSpeed,
                    this.getControl(RigidBodyControl.class).getLinearVelocity().y,
                    cam.getCam().getDirection().z*playerWalkSpeed             
        ));
            break;
        case "down":
        this.getControl(RigidBodyControl.class).setLinearVelocity(new Vector3f(
                    -1f * cam.getCam().getDirection().x*playerWalkSpeed,
                    this.getControl(RigidBodyControl.class).getLinearVelocity().y,
                    -1f * cam.getCam().getDirection().z*playerWalkSpeed             
        ));
            break;
    }
    //System.out.println(cam.getCam().getDirection().x * (0.6f - this.getControl(RigidBodyControl.class).getLinearVelocity().x)/playerWalkSpeed);
    System.out.println(this.getControl(RigidBodyControl.class).getPhysicsRotation());
}

}

this is the class

8

A good way to block the rotation of a rigid body is to set its “angular factors” to zero:

body.setAngularFactor(new Vector3f(0f, 0f, 0f));

For more information see the Minie tutorial on rigid bodies.