# Help with drawing a "rose" that draws each "petal" with a different random color
**URL:** https://discourse.processing.org/t/help-with-drawing-a-rose-that-draws-each-petal-with-a-different-random-color/24654
**Category:** Coding Questions
**Tags:** homework
**Created:** [October 16, 2020, 11:02pm UTC](https://discourse.processing.org/t/help-with-drawing-a-rose-that-draws-each-petal-with-a-different-random-color/24654 "2020-10-16T23:02:27Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@kimchi](https://discourse.processing.org/u/kimchi)
#### Post date: [October 16, 2020, 11:02pm UTC](https://discourse.processing.org/t/help-with-drawing-a-rose-that-draws-each-petal-with-a-different-random-color/24654/1 "2020-10-16T23:02:27Z")
Hi I need some help on this one program that draws a mathematical rose where it draws each petal of the rose as a different random color. When I run my code it only draws half of each petal as a random color and the other halves as striped rainbows. I’m pretty new to booleans and I’m unsure how to approach this problem.
```auto
//constants
final float K = 4; //The factor that controls the number of "petals"
final float RATE = 0.02; //The change in t each frame. Controls speed and smoothness.
final float ROSE_RADIUS = 200; //The radius, in pixels, of the "rose"
//state variables
float t = 0; //The "parameter" t which will slowly change from 0 to 2PI
float prevX;
float prevY;
float distance;
float previousDistance;
boolean moveTowardsCenter;
void setup() {
size(500, 500); //make a 500x500 canvas
background(0); //Use a black background
strokeWeight(2); //make thicker lines
stroke(255); //make lines white
//Precalculate the first point
prevX=width/2+ROSE_RADIUS;
prevY=height/2;
}
void draw() {
//Calculate the new point
float x = cos(K*t)*cos(t)*ROSE_RADIUS+width/2;
float y = cos(K*t)*sin(t)*ROSE_RADIUS+height/2;
distance = sqrt(pow((x-prevX), 2) + pow((y-prevY), 2));
println(distance);
if (distance>previousDistance) {
stroke(random(255), random(255), random(255));
}
previousDistance = distance;
line(prevX, prevY, x, y); //draw the next line
//Keep all the information needed for next time
prevX = x;
prevY = y;
//Advance t
t += RATE;
}
```
---
### Author:  [@glv](https://discourse.processing.org/u/glv)
#### Post date: [October 17, 2020, 12:32am UTC](https://discourse.processing.org/t/help-with-drawing-a-rose-that-draws-each-petal-with-a-different-random-color/24654/2 "2020-10-17T00:32:55Z")
Hello,
Suggestion using your “distance” approach:
- translate(width/2, height/2) so center of canvas is (0,0)
- If distance from (0, 0) to (x, y) \< threshold then random color
You can pick the threshold you want to trigger a color change.
Not perfect so I put a circle in the middle.
You can also check for t every increment of TWO\_PI/8; that is a bit more complicated.
Also take a look at the random() function in the reference:
_[https://processing.org/reference/random\_.html](https://processing.org/reference/random_.html)_
You will only get a random number up to 255 but not including 255.
`:)`
---
### Author:  [@kimchi](https://discourse.processing.org/u/kimchi)
#### Post date: [October 17, 2020, 4:25am UTC](https://discourse.processing.org/t/help-with-drawing-a-rose-that-draws-each-petal-with-a-different-random-color/24654/3 "2020-10-17T04:25:58Z")
Thanks for the suggestions! When would I use the translate() function? Sorry I’m taking an introductory course and we’ve never used translate yet
---
### Author:  [@glv](https://discourse.processing.org/u/glv)
#### Post date: [October 17, 2020, 11:26am UTC](https://discourse.processing.org/t/help-with-drawing-a-rose-that-draws-each-petal-with-a-different-random-color/24654/4 "2020-10-17T11:26:41Z")
Hello,
> [@kimchi](#):
>
> When would I use the translate() function?
It is up to you if you choose to use it; it was easier for me when working through your code to have origin at center (width/2, height/2) of screen.
_[translate() / Reference / Processing.org](https://processing.org/reference/translate_.html)_
_[2D Transformations / Processing.org](https://processing.org/tutorials/transform2d/)_
_[width / Reference / Processing.org](https://processing.org/reference/width.html)_
```auto
void setup()
{
size(200, 200);
}
void draw()
{
background(0);
translate(width/2, height/2);
textSize(24);
textAlign(CENTER, CENTER);
text("0,0", 0, 0); // Prints at x = 0, y = 0
}
```
There is a dist() function:
_[dist() / Reference / Processing.org](https://processing.org/reference/dist_.html)_
You are already doing the math `:)` and dist() is the same thing wrapped in a function.
Stick to what you are comfortable with and requirements of your academic assignment.
`:)`