OnTriggerEnter AddForce

Questions & Answers
1

Hi there,

I have a quick problem with the syntax of using OnTriggerEnter where i want a falling cube to hit a paddle and bounce back up like on a trampoline. I realise this is one of the most obvious of unity questions but I have scoured the internet and simply cant find an example of the javascript i require. (I have used a Collider instead of trigger but because I’m using a cube it would hit the paddle and fall to one side and then go crazy, I’m looking for a smooth almost stylised bounce (not sending it flying with crazy rotations) regardless of the shape of the collider.

I’m using variations of the following…

var bounceSpeed : float = 8;
	
function OnTriggerEnter(thing: Collider){
  if (thing.tag == "trampoline"){
  	
  	cube.rigidbody.AddForce(bounceSpeed * Vector3.up, ForceMode.Force);
  }
}

and nothing is working.
I am attaching that script to the ‘cube’ and making the cube a trigger.
I know this has been posted many times but every example im trying to change for my own use is failing. Any help would be great.

Thanks in advance.

2

To get the behaviour you want, I think that you should modify rigidbody.velocity directly: the cube must revert its movement instantly, what’s very difficult to achieve applying a force. Try the following:

var bounceSpeed : float = 8;
	
function OnTriggerEnter(thing: Collider){
  if (thing.tag == "trampoline"){
    cube.rigidbody.velocity = bounceSpeed * Vector3.up;
  }
}

The docs say don’t change rigidbody.velocity yourself to avoid unnatural reactions - but in this case that’s exactly what you want: unnatural reaction!