Issue using Vector3.Reflect to bounce a ball

Question

Hello everyone, having a rather annoying issue. Setting up a simple ball bouncing game, set up some code to have the ball reflect off a surface. It works great on my 4 walls, but it will not reflect off my paddle. Reflects off the walls, hits the paddle, then it just stops. I have gotten rid of any code that could be causing this, even turned the paddle into a simple cube and it still happens.

This is the code that is attached to the bouncing balls that causes the reflection

 void OnCollisionEnter(Collision collisionInfo)
     {
 
         rigidbody.AddForce(Vector3.Reflect(transform.position, 
                            collisionInfo.contacts[0].normal) * reflectSpeed, ForceMode.Impulse);//this causes the ball to reflect off the surface
         transform.rotation = Quaternion.LookRotation(rigidbody.velocity);//this rotates the ball to face in the direction it is moving
 
     }

Kind of at a loss with this one. The paddle is not a rigidbody, the balls are. The only script attached to the paddle makes it rotate around a point, and I even turned that off and it made no difference.

Here is a link to a cut down to the bones version of what I am doing, just shows the bouncing issue.

Bare Bones

Thanks!

Answer 1

Update: this is probably easiest to do by adding a Physic Material (create Physic Material in assets window) to your ball, and setting Bounciness to 1 and Bounce Combine to Maximum. that gets it bouncing properly. if you need the bumper effect from pinball machines, then you could use something like:

 void OnCollisionEnter (Collision c) {
         // bumper effect to speed up ball
         myRigidbody.AddForce(c.contacts[0].normal*bumperForce, ForceMode.Impulse);
     }

if you want to bypass the physics engine's collision and do your own then personally i wouldn't use addforce, i would just directly mess with the velocity. or maybe just use addforce on the "bumper" part so that bouncing objects of different masses would get bounced differently.

also i tested why you were having issues, and i believe it is because the physics engine is handling the collision and killing the ball's velocity before you get your hands on it. to work around that i continually save the velocity. maybe there is a way to tell the physics engine not to actually perform the collision which would be much neater, but this works :)

i included 2 ways of bouncing, and added a "bumper boost" that it seems like you wanted... if you want to do it with multiplication instead of addition that should be pretty straight forward too.

 using UnityEngine;
 using System.Collections;
 
 public class ballScript : MonoBehaviour {
     
     Rigidbody myRigidbody;
     Vector3 oldVel;
 
     void Start () {
         myRigidbody = GetComponent<Rigidbody>();
     }
     
     void FixedUpdate() {
         oldVel = myRigidbody.velocity;
     }
     
     void OnCollisionEnter (Collision c) {
         ContactPoint cp = c.contacts[0];
         // calculate with addition of normal vector
         // myRigidbody.velocity = oldVel + cp.normal*2.0f*oldVel.magnitude;
         
         // calculate with Vector3.Reflect
         myRigidbody.velocity = Vector3.Reflect(oldVel,cp.normal);
         
         // bumper effect to speed up ball
         myRigidbody.velocity += cp.normal*2.0f;
     }
 }

Issue using Vector3.Reflect to bounce a ball

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