[SOLVED] VehicleControl wheels digging into the ground

Troubleshooting physics
1

I’m having trouble with my VehicleControl wheels digging into the floor and inhibiting the movement of my vehicle. I’m trying to collide with an obj model using RigidBodyControl.

My car class:

package mygame;

import com.jme3.bullet.collision.shapes.BoxCollisionShape;
import com.jme3.bullet.collision.shapes.CompoundCollisionShape;
import com.jme3.bullet.control.VehicleControl;
import com.jme3.material.Material;
import com.jme3.math.FastMath;
import com.jme3.math.Quaternion;
import com.jme3.math.Vector3f;
import com.jme3.scene.Geometry;
import com.jme3.scene.Node;
import com.jme3.scene.Spatial;
import com.jme3.scene.shape.Cylinder;

/**
 *
 * @author codex
 */
public class Car {
	
	float x, y, z;
	Spatial model;
	Material mat;
	
	CompoundCollisionShape compoundShape;
	BoxCollisionShape box;
	Node vehicleNode = new Node("car");
	
	VehicleControl vehicle = new VehicleControl();
	float accel = 1.5f;
	float turn = 0f;
	Vector3f grav = new Vector3f(0, -1, 0);
	float friction = 0.7f;
	float mass = 0.8f;
	float stiffness = 60.0f;
	float compValue = .3f;
	float dampValue = .4f;
	
	Vector3f wheelDirection = new Vector3f(0, -1, 0);
	Vector3f wheelAxle = new Vector3f(-1, 0, 0);
	float radius = 1f;
	float restLength = 0.3f;
	float xOff = 3f;
	float yOff = -1f;
	float zOff = 2f;
	
	
	Car(float x, float y, float z, Spatial model, Material mat) {
		this.x = x;
		this.y = y;
		this.z = z;
		this.model = model;
		this.mat = mat;
	}
	
	protected Node createVehicle() {
		compoundShape = new CompoundCollisionShape();
		box = new BoxCollisionShape(new Vector3f(1.2f, 0.5f, 2.4f));
		compoundShape.addChildShape(box, new Vector3f(0, 1, 0));
		vehicle = new VehicleControl(compoundShape, 400);
		model.setMaterial(mat);
		Quaternion rotate = new Quaternion();
		rotate.fromAngleAxis(0.5f*FastMath.PI, new Vector3f(0, 1, 0));
		model.setLocalRotation(rotate);
		vehicle.setSpatial(model);
		buildWheels();
		//vehicle.setGravity(grav);
		//vehicle.setRollInfluence(0, turn);
		//vehicle.setFriction(friction);
		vehicle.setMass(mass);
		vehicle.setSuspensionCompression(compValue * 2.0f * FastMath.sqrt(stiffness));
		vehicle.setSuspensionDamping(dampValue * 2.0f * FastMath.sqrt(stiffness));
		vehicle.setSuspensionStiffness(stiffness);
		vehicle.setMaxSuspensionForce(10000.0f);
		//vehicle.setPhysicsLocation(new Vector3f(x, y, z));
		vehicleNode.attachChild(model);
		vehicleNode.addControl(vehicle);
		return vehicleNode;
	}
	private void buildWheels() {
		Node wbl = new Node("back left wheel");
		Node wbr = new Node("back right wheel");
		Node wfl = new Node("front left wheel");
		Node wfr = new Node("front right wheel");
		Cylinder wheelMesh = new Cylinder(16, 16, radius, radius * 0.6f, true);
		// connectionPoint, direction, axle, suspensionRestLength, wheelRadius, isFrontWheel
		// back wheel left
		Geometry wheels1 = new Geometry("wheel 1", wheelMesh);
		wfl.attachChild(wheels1);
		wheels1.rotate(0, FastMath.HALF_PI, 0);
		wheels1.setMaterial(mat);
		vehicle.addWheel(wfl, new Vector3f(-xOff, yOff, zOff),
				wheelDirection, wheelAxle, restLength, radius, true);
		// back wheel right
		Geometry wheels2 = new Geometry("wheel 2", wheelMesh);
		wfr.attachChild(wheels2);
		wheels2.rotate(0, FastMath.HALF_PI, 0);
		wheels2.setMaterial(mat);
		vehicle.addWheel(wfr, new Vector3f(xOff, yOff, zOff),
				wheelDirection, wheelAxle, restLength, radius, true);
		// front wheel left
		Geometry wheels3 = new Geometry("wheel 3", wheelMesh);
		wbl.attachChild(wheels3);
		wheels3.rotate(0, FastMath.HALF_PI, 0);
		wheels3.setMaterial(mat);
		vehicle.addWheel(wbl, new Vector3f(-xOff, yOff, -zOff),
				wheelDirection, wheelAxle, restLength, radius, false);
		// front wheel right
		Geometry wheels4 = new Geometry("wheel 4", wheelMesh);
		wbr.attachChild(wheels4);
		wheels4.rotate(0, FastMath.HALF_PI, 0);
		wheels4.setMaterial(mat);
		vehicle.addWheel(wbr, new Vector3f(xOff, yOff, -zOff),
				wheelDirection, wheelAxle, restLength, radius, false);
		vehicleNode.attachChild(wbl);
		vehicleNode.attachChild(wbr);
		vehicleNode.attachChild(wfl);
		vehicleNode.attachChild(wfr);
	}
	
	protected void forward() {
		vehicle.accelerate(accel);		
	}
	protected void steer(String binding, boolean isPressed) {
		if (binding.equals(Main.LEFT)) {
			if (isPressed) { turn += .5f; } else { turn += -.5f; }
		} else if (binding.equals(Main.RIGHT)) {
			if (isPressed) { turn += -.5f; } else { turn += .5f; }
		}
		vehicle.steer(turn);
	}
	protected void steerLeft() {
		vehicle.steer(-turn);
	}
	
	protected VehicleControl getPhysics() {
		return vehicle;
	}
	protected Vector3f getPos() {
		return vehicle.getPhysicsLocation();
	}
	protected Vector3f getDirection() {
		return vehicle.getForwardVector(grav);
	}
	
}
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2

If you didnot play too much the values the suspension(Spring compression ) , stiffness(rigidity) & damping (Spring release) , you wonot get this unless you are spawning the car at 0,0,0 & the ground at 0,2,0 & the ground can have thickness , so beware of your spawning code .

I havenot worked too much with those parameters but what I know that the damping should be higher than suspension value or compression & that’s true here

3

I copied the suspension, stiffness, and damping values from the VehicleControl tutorial. I’m spawning the car at {0, 0, 0} and my ground model at {0, -2, 0}.

Vehicle Tutorial

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4

If you havenot already added the car to the physics please check it , because , the wheels may be not added to the physics .

5

When I played around with the vehicle control stuff and things acted weird, I’d compare my code to the vehicle tests in jme3-examples… figure out what I was doing differently, and correct the issue.

The code in the tutorial is on a web page so is not guaranteed to work all the time.

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6

Try building wheels after setting car properties , because as suspected , physics would have applied effects if you call the buildwheels(); after the car spring properties which are the car wheels properties indeed so ,

{initializeWheels ->then-> apply wheels properties}

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7

Problem solved.
I was building my wheels before setting up other vehicle characteristics.

Thanks y’all!

PS: Is there a way to put the camera directly behind the car?

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8
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9

There is also a tuning guide and some simple examples in Minie’s vehicle-physics tutorial:

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