Rotate GameObject based on RigidBody Velocity

Question

Hello,

Just wondering if someone would be kind enough to help me work something out (in C# preferably).

Basically I have a cube with a little propeller on the top of it. The cube has a Rigidbody and is controlled by keys (for forwards/backwards motion). I am trying to work out how to make the propeller rotate (clockwise/anti-clockwise on Y axis) based on the RigidBody’s Velocity.

Ideally I am wanting to be able to drag the object with the RigidBody component and the propellor GameObject onto the script in the inspector.

I have a ‘faked’ solution where it rotates the propellor based on key input and a float for rotation speed but as soon as I am not holding down a key it stops rotating so it looks a bit silly to see the cube slowing down and the propellor has already stopped rotating.

Any help would be very much appreciated.

Answer 1

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class PlayerRotObject : MonoBehaviour 
 {
 
     // SPEED = DISTANCE / TIME
 
     public Vector3 localV;
 
     public float RBVelo;
 
     public float WheelRadius=2.35f; 
 
     public GameObject thisObject;     // Object with Rigidbody
     public GameObject leftProp;        // Left Propellor Object
     public GameObject rightProp;    // Right Propellor Object
     private Rigidbody thisRB;
 
     Vector3 currentPosition;
 
     // Use this for initialization
     void Start () 
     {
         
         thisRB = thisObject.GetComponent<Rigidbody>();
 
 
     }
     
     // Update is called once per frame
     void Update () 
     {
         RBVelo = thisRB.velocity.magnitude;
 
         Vector3 localVelocity = transform.InverseTransformDirection( thisRB.velocity );
         // Just to visualize in the inspector
         localV = localVelocity;
 
         float dir_mult = 1; // Determine direction to "spin" the wheel; 1 is forward, -1 is backward
         if(localVelocity.z < 0) dir_mult = -1;
 
         // Magnitude * time.deltaTime is basically the "distance" the rb traveled
         //  So, we need to figure out how much to "spin" the wheels...
         // this ONLY takes into account SPEED, not DIRECTION.  So, if hte car is moving backwards,
         // we'd need to actually multiply by -1
         float degRot = ( (RBVelo * Time.deltaTime) / WheelRadius) * Mathf.Rad2Deg * dir_mult;
         leftProp.transform.Rotate( degRot, 0, 0 );
         rightProp.transform.Rotate( degRot, 0, 0 );
 
     }
 }

Rotate GameObject based on RigidBody Velocity

1 Reply

Your answer

Follow this Question

Related Questions