# Rotation an object using processing
**URL:** https://discourse.processing.org/t/rotation-an-object-using-processing/2089
**Category:** Coding Questions
**Created:** [July 26, 2018, 1:40am UTC](https://discourse.processing.org/t/rotation-an-object-using-processing/2089 "2018-07-26T01:40:10Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@bill](https://discourse.processing.org/u/bill)
#### Post date: [July 26, 2018, 1:40am UTC](https://discourse.processing.org/t/rotation-an-object-using-processing/2089/1 "2018-07-26T01:40:10Z")
Hi there,
I am new to processing. I have an idea to do a sketch of tower crane’s top view. so I have two objects to consider one is the jib rotating and the second is the trolley moving along the jib. I have did the part of rotating jib using arrow keys, however I stuck how to move the trolley along the jib… I would be thankful for your help here is my code below:
```auto
float xo;
float yo;
float x;
float y;
float angle=0;
float rh=0;
void setup(){
size (800,600);
xo= width/2;
yo=height/2;
smooth();
noStroke();
}
void draw(){
background(0);
translate(xo, yo);
rotate(angle);
fill(255,255 ,255);
rect (5, -20, 30,30);
pushMatrix();
fill (255,0,0);
rect (0, 0, 300, 10);
popMatrix();
}
void keyPressed(){
if (key==CODED){
if (keyCode== RIGHT){
angle+= 1;
}else if (keyCode== LEFT){
angle-= 1;
if (keyCode== UP){
xo+= 1;
}else if (keyCode== DOWN){
yo-= 1;
}
if (key==' ')
{
angle = 0;
rh = 0 ;
xo = width/2;
yo = height/2;
}
}
}
}
```
---
### Author:  [@kfrajer](https://discourse.processing.org/u/kfrajer)
#### Post date: [July 26, 2018, 1:54am UTC](https://discourse.processing.org/t/rotation-an-object-using-processing/2089/2 "2018-07-26T01:54:33Z")
You need to format your code. Edit your post, select your code and hit the `` button. In your code, notice the space character is not part of the coded keys, so it should be outside that if statement. Check the code below. Notice I added an else keyword that you missed.
Kf
```java
void keyPressed() {
if (key==CODED) {
if (keyCode== RIGHT) {
angle+= 1;
} else if (keyCode== LEFT) {
angle-= 1;
} else if (keyCode== UP) {
xo+= 1;
} else if (keyCode== DOWN) {
yo-= 1;
}
}
if (key==' ')
{
angle = 0;
rh = 0 ;
xo = width/2;
yo = height/2;
}
}
```
---
### Author:  [@bill](https://discourse.processing.org/u/bill)
#### Post date: [July 26, 2018, 2:02am UTC](https://discourse.processing.org/t/rotation-an-object-using-processing/2089/3 "2018-07-26T02:02:43Z")
thank you Kfrajer for your reply, I appreciate that,
I edited the post. what I meant that the jib rotate perfectly there is nothing wrong with it , but my question was regarding the trolley which is represented by white square , I need this trolley(white square) move along the jib when I hit the (up ,down) keys while the the jib (red line)does not move only rotate.
Cheers
---
### Author:  [@TfGuy44](https://discourse.processing.org/u/TfGuy44)
#### Post date: [July 26, 2018, 4:06am UTC](https://discourse.processing.org/t/rotation-an-object-using-processing/2089/4 "2018-07-26T04:06:41Z")
Consider this code:
```auto
float xo;
float angle=0;
void setup() {
size(800, 600);
smooth();
noStroke();
reset();
}
void reset() {
angle = 0;
xo = 0;
}
void draw() {
background(0);
translate(width/2, height/2);
rotate(angle);
pushMatrix();
translate(5, -20);
fill(255, 255, 255);
rect(xo, 0, 30, 30);
popMatrix();
fill (255, 0, 0);
rect (0, 0, 300, 10);
}
void keyPressed() {
if (key==CODED) {
if (keyCode== RIGHT) {
angle+= radians(1);
} else if (keyCode== LEFT) {
angle-= radians(1);
} else if (keyCode== UP) {
xo+= 1;
} else if (keyCode== DOWN) {
xo-= 1;
}
}
if (key==' ') {
reset();
}
}
```
Notice the complete lack of a `y0` variable!
---
### Author:  [@bill](https://discourse.processing.org/u/bill)
#### Post date: [July 28, 2018, 9:36am UTC](https://discourse.processing.org/t/rotation-an-object-using-processing/2089/5 "2018-07-28T09:36:39Z")
thank you TfGuy44, I appreciate your cooperative. Indeed yes, I know that yo is variable, but I do not know how to translate it into a code. thanks again.
Cheers
Bilal
---
### Author:  [@kfrajer](https://discourse.processing.org/u/kfrajer)
#### Post date: [July 29, 2018, 4:53am UTC](https://discourse.processing.org/t/rotation-an-object-using-processing/2089/6 "2018-07-29T04:53:17Z")
I believe Thomas provided you the answer. In his post, he mentioned that you do not need y0 but only x0 is enough. You need to have a look at the [transformation tutorial](https://processing.org/tutorials/transform2d/) so you can understand what he means.
Kf
---
### Author:  [@bill](https://discourse.processing.org/u/bill)
#### Post date: [July 30, 2018, 1:45am UTC](https://discourse.processing.org/t/rotation-an-object-using-processing/2089/7 "2018-07-30T01:45:15Z")
Thank you Kf… I looked at the link that you have provided.
Cheers
---
### Author:  [@kfrajer](https://discourse.processing.org/u/kfrajer)
#### Post date: [July 30, 2018, 1:52am UTC](https://discourse.processing.org/t/rotation-an-object-using-processing/2089/8 "2018-07-30T01:52:39Z")
Did the link help?
Kf
---
### Author:  [@bill](https://discourse.processing.org/u/bill)
#### Post date: [July 31, 2018, 1:14am UTC](https://discourse.processing.org/t/rotation-an-object-using-processing/2089/9 "2018-07-31T01:14:52Z")
yes. I appreciate your cooperative. Thanks Kf