# Dist from mouse to ellipse
**URL:** https://discourse.processing.org/t/dist-from-mouse-to-ellipse/18157
**Category:** Coding Questions
**Created:** [February 26, 2020, 8:47pm UTC](https://discourse.processing.org/t/dist-from-mouse-to-ellipse/18157 "2020-02-26T20:47:34Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@NotConsumable](https://discourse.processing.org/u/NotConsumable)
#### Post date: [February 26, 2020, 8:47pm UTC](https://discourse.processing.org/t/dist-from-mouse-to-ellipse/18157/1 "2020-02-26T20:47:34Z")
i am trying to make 4 different circles appear around my mouse depending how far away i am from a randomly occurring ellipse and i was wondering how i would implement a dist function within an if statement in order to make the circle appear around my mouse based on my mouse’s location in relation to how far away i am from the ellipse.
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### Author:  [@Chrisir](https://discourse.processing.org/u/Chrisir)
#### Post date: [February 26, 2020, 8:54pm UTC](https://discourse.processing.org/t/dist-from-mouse-to-ellipse/18157/2 "2020-02-26T20:54:15Z")
look at the dist() command in the reference [https://www.processing.org/reference/](https://www.processing.org/reference/)
not fully sure what you want but maybe:
```auto
float myDist = dist(....................
if(myDist>=0 && myDist<50) {
// draw one circle
}
else if(myDist>=50 && myDist<150) {
// draw 2 circles
}
else if(myDist>=150 && myDist<250) {
// draw 3 circles
}
else if(myDist>=250 ) {
// draw 4 circles
}
```
Chrisir
---
### Author:  [@jeremydouglass](https://discourse.processing.org/u/jeremydouglass)
#### Post date: [March 3, 2020, 6:55pm UTC](https://discourse.processing.org/t/dist-from-mouse-to-ellipse/18157/3 "2020-03-03T18:55:17Z")
Do you want distance from the center of the ellipse, or distance from the closest edge point on the ellipse? Distance from a circle is quite easy – you take the point distance and subtract the radius. Distance from an ellipse is surprisingly hard – so much so that it is not covered in most major coliision detection tutorials.
> As with any book, there’s a lot more useful material than could be covered here. Things that aren’t discussed are mostly left out because the math gets too complicated. Three-dimensional space isn’t touched on. Ellipses, which seem like they should be pretty easy, are actually very difficult. [Collision Detection](http://www.jeffreythompson.org/collision-detection/index.php)
Although, if you want to implement it, there is a survey of the math with pseudocode here:
- [https://www.geometrictools.com/Documentation/DistancePointEllipseEllipsoid.pdf](https://www.geometrictools.com/Documentation/DistancePointEllipseEllipsoid.pdf)
I implemented ellipse collision detection in a library a while back – but that expresses distance as a ratio \>1 rather than as an absolute distance to the closest point on the ellipse (it doesn’t scale the same in x and y). This works fine for collision detection because you only care if the value is \<1 or not (colliding).