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Question by pepperedereppep · Nov 13, 2010 at 02:26 AM · animationballbounce

bouncing ball without physics/gravity

Hey, another quick question here from a beginner. II'm playing around with code and right now I'm trying to figure out how to create a bouncing ball without using any physics/force/gravity. I'm basically trying to learn how this kinda coding works so I can apply it to other things that aren't exactly meant to be physics based.. here it is so far(not very far :)):

var YMovement : float = 0; var damp:float; var fall:float; var jump:boolean=false;

function Update () {
if(jump==false){ YMovement = Mathf.Lerp(YMovement, -1, Time.deltaTime*damp); transform.Translate (0,YMovement 12 Time.deltaTime, 0); }else if(jump==true){ transform.position.y+=fall*Time.deltaTime; //??? } }
function OnTriggerEnter(col:Collider){ if(col.gameObject.tag=="ground"){ jump=true; } }

this code is attached to a box that would be bouncing on top of another box tagged as "ground". Right now after the bounce all I have is the ball shooting towards the positive y axis, but the initial fall is the way I want it ..Any pointer on how to do this or if I'm even doing it right would be greatly appreciated.

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avatar image ChimpKing · Nov 13, 2010 at 02:46 AM 0
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You could just apply a bouncy physics material.... it's in one of the packages.

avatar image pepperedereppep · Nov 13, 2010 at 03:15 AM 0
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Hey. As I said, I'm not using physics/gravity. I don't even intent to use this code for a ball bounce, I just want to know how one would go about writing a code like this

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Answer by Eric5h5 · Nov 13, 2010 at 03:37 AM

To do it totally programmatically without physics, you can do something like this:

var bounceSpeed = 1.0; var bounceAmount = 2.0;

function Start () { while (true) { var t = 0.0; while (t < 1.0) { t += Time.deltaTime bounceSpeed; transform.position.y = Bounce(t) bounceAmount; yield; } } }

function Bounce (t : float) : float { return Mathf.Sin(Mathf.Clamp01(t) * Mathf.PI); }

Edit: actually you can remove the Start function and use this if you wanted the bouncing to continue forever:

function Update () {
    transform.position.y = Bounce((Time.time * bounceSpeed)%1) * bounceAmount;
}

If you wanted to limit the number of bounces, though, then keep the Start function and replace "while (true)" with "for (i = 0; i < 10; i++)" for 10 bounces, etc.

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avatar image pepperedereppep · Nov 13, 2010 at 04:35 AM 0
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thanks! looks like what I want. Now I'm going to stare at the code for a while to figure out what's going on :) Thank you!

avatar image pepperedereppep · Nov 13, 2010 at 05:45 AM 0
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hey Eric, thanks a lot. I was wondering with that bounce function is it possible to have a trigger bounce the object back up rather than having it be based on time?

avatar image Maltus · Nov 13, 2010 at 05:50 AM 0
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Eric5h5 You are awesome, Thanks for all the help you have given.

avatar image Eric5h5 · Nov 13, 2010 at 06:29 AM 0
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@pepperedereppep: in order for triggers to work you need a rigidbody, in which case you might as well use physics/gravity to do the bouncing too.

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Answer by pepefirst · Jun 08, 2012 at 12:07 AM

This script is simply GREAT!

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