# How to make object bounce off another object
**URL:** https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595
**Category:** Coding Questions
**Created:** [March 25, 2019, 7:13am UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595 "2019-03-25T07:13:03Z")
**Posts on this page:** 17
**Page:** 1
### Author:  [@Bobby](https://discourse.processing.org/u/Bobby)
#### Post date: [March 25, 2019, 7:13am UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/1 "2019-03-25T07:13:03Z")
Have gotten down how to make a ball bounce with gravity. Now I want that ball to hit a moving object and bounce off it. Any help on how to to do that?
---
### Author:  [@kll](https://discourse.processing.org/u/kll)
#### Post date: [March 25, 2019, 7:32am UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/2 "2019-03-25T07:32:47Z")
-a- check ( every draw loop ) for the distance between the 2 objects
[https://processing.org/reference/dist\_.html](https://processing.org/reference/dist_.html)
if that is smaller as the sum of the 2 radius BOUNCE
-b- for the bounce could have easy … complicated rules:
- just change the speed vector of the ball
- change speed vector of ball and object
- apply physics math of impuls F \* t = mass \* delta speed m\*dv
- if not center collision find a rebounce angula
---
### Author:  [@Bobby](https://discourse.processing.org/u/Bobby)
#### Post date: [March 25, 2019, 10:08am UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/3 "2019-03-25T10:08:56Z")
```auto
the x-value of my object is mouseX.
Actually, ill send my code if you would like to help:
float circleX=1; //direction of ball
float circleY=1; //direction of ball
float speedX=3;//speed of ball
float speedY=1;
float xpos; //position of ball
float ypos; //position of ball
void setup() {
size(640,480);
//starting position of ball
xpos=0;
ypos=0;
}
void draw() {
//background of game
background(44,56,245);
fill(2,188,34);
noStroke();
rect(0,440,width,height);
//Bill Movement
pushMatrix();
translate(mouseX,280);
Bill();
popMatrix();
//Ball
ypos+=speedY;
xpos+=speedX;
//Ball
fill(180);
stroke(0);
strokeWeight(2);
ellipse(xpos,ypos,50,50);
//if ball goes out of area, turn it back
if(xpos>width-50 || xpos<0){
speedX*=-1;
}
//grav
if(ypos>height-50){
speedY*=-1*.99;
}else{
speedY+=1;
}
if(ypos<0){
speedY*=-1;
}
//Ball reset
if(speedY==0){
xpos=0;
ypos=0;
}
}
Btw my object is Bill()
```
---
### Author:  [@Chrisir](https://discourse.processing.org/u/Chrisir)
#### Post date: [March 25, 2019, 10:26am UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/4 "2019-03-25T10:26:15Z")
See here
Strip the gravity
[https://processing.org/examples/bouncybubbles.html](https://processing.org/examples/bouncybubbles.html)
---
### Author:  [@Bobby](https://discourse.processing.org/u/Bobby)
#### Post date: [March 25, 2019, 12:39pm UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/5 "2019-03-25T12:39:56Z")
Can’t, i have to have it included for my question.
Basically im supposed to juggle the ball on my characters head
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### Author:  [@Chrisir](https://discourse.processing.org/u/Chrisir)
#### Post date: [March 25, 2019, 12:41pm UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/6 "2019-03-25T12:41:36Z")
Okay, I just wanted to show you the example
Chrisir
---
### Author:  [@Bobby](https://discourse.processing.org/u/Bobby)
#### Post date: [March 25, 2019, 12:49pm UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/7 "2019-03-25T12:49:17Z")
thanks anyway,
Bobby
---
### Author:  [@kll](https://discourse.processing.org/u/kll)
#### Post date: [March 25, 2019, 1:00pm UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/8 "2019-03-25T13:00:09Z")
pls format you code by
PASTE it into
```auto
code formatter
```
and i think there is the code for the other object missing
did you start about the distance calculation?
---
### Author:  [@Bobby](https://discourse.processing.org/u/Bobby)
#### Post date: [March 25, 2019, 2:36pm UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/9 "2019-03-25T14:36:26Z")
Sorry about that! Yeah i was abit confused about the distance from the points as the ball would constantly bouncing, while the character would follow my mouseX.
i left out the code of the character as i thought would be abit messy and that its just a group of shapes lol. Thank you for spending ur time to help me btw.
---
### Author:  [@kll](https://discourse.processing.org/u/kll)
#### Post date: [March 25, 2019, 3:07pm UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/10 "2019-03-25T15:07:45Z")
so you just make it a rectangle.
bill.x by mouseX, bill.y fix 280,
the width bill.w of the rect would be critical for the bounce
( collision check with the ball )
in words:
if ball ( center ) posx \> bill.x but \< bill.x+bill.w a bounce is possible.
when ball posy \< bill.y ( and fall down ) it will hit:
if ball posy+radius \>= bill.y
and what would happen then? bounce up like from ground?
---
### Author:  [@Bobby](https://discourse.processing.org/u/Bobby)
#### Post date: [March 25, 2019, 3:23pm UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/11 "2019-03-25T15:23:36Z")
ill show you my character. I do not understand how i can make a variable for Bills position;
```auto
void Bill(){
fill(0);
rect(100,100,60,50); //head
fill(255);
rect(110,120,15,5); //left eye
rect(135,120,15,5); //right eye
ellipse(130,136,10,2); //mouth
fill(0);
rect(85,96,90,4); //hat
fill(250,105,73);
rect(110,150,40,20); //body
fill(0);
rect(110,170,5,10); //left foot
rect(145,170,5,10); //right foot
}
```
---
### Author:  [@kll](https://discourse.processing.org/u/kll)
#### Post date: [March 25, 2019, 3:32pm UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/12 "2019-03-25T15:32:04Z")
the bounce line would be top of HAT?
bill\_x = mouseX+85; // translate + hat x
bill\_y = 280+96; // fix in translate + hat y
bill\_w = 90; // hat rect w
---
### Author:  [@Bobby](https://discourse.processing.org/u/Bobby)
#### Post date: [March 26, 2019, 7:48am UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/13 "2019-03-26T07:48:22Z")
```auto
billX= mouseX + 85;
billY= 280 + 96;
billW= 90;
if(xpos == billX){
speedX*=-1;
}
if (ypos == billY){
speedY*=-1;
}
```
it bounces off something now, im not sure what. Also im not sure how to implement that the width of the hat is area to bounce off- reason to why billW is not being used
---
### Author:  [@kll](https://discourse.processing.org/u/kll)
#### Post date: [March 26, 2019, 8:56am UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/14 "2019-03-26T08:56:31Z")
> [@kll](#):
>
> in words:
> if ball ( center ) posx \> bill.x but \< bill.x+bill.w a bounce is possible.
> when ball posy \< bill.y ( and fall down ) it will hit:
> if ball posy+radius \>= bill.y
- untested idea
```auto
billX= mouseX + 85;
billY= 280 + 96;
billW= 90;
if((xpos >= billX) && (xpos <= billX+billW)) {
if (ypos + radius >= billY){
speedX*=-1;
speedY*=-1;
}
}
```
---
### Author:  [@Blink\_Once](https://discourse.processing.org/u/Blink_Once)
#### Post date: [April 4, 2019, 10:14am UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/15 "2019-04-04T10:14:08Z")
Hi, did you manage to get your code to work?
---
### Author:  [@Bobby](https://discourse.processing.org/u/Bobby)
#### Post date: [April 4, 2019, 12:32pm UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/16 "2019-04-04T12:32:50Z")
No ☹ sadly the code will still not make the ball bounce of the hat.
I think the reason has to do with the positioning of my character. Maybe i should make my hat a separate entity and work from there?
---
### Author:  [@Blink\_Once](https://discourse.processing.org/u/Blink_Once)
#### Post date: [April 4, 2019, 11:54pm UTC](https://discourse.processing.org/t/how-to-make-object-bounce-off-another-object/9595/17 "2019-04-04T23:54:59Z")
I have a similar question and i have no idea how to work it out as well that’s why i was asking