# Finding pixels inside a shape
**URL:** https://discourse.processing.org/t/finding-pixels-inside-a-shape/1829
**Category:** Coding Questions
**Created:** [July 16, 2018, 8:15pm UTC](https://discourse.processing.org/t/finding-pixels-inside-a-shape/1829 "2018-07-16T20:15:53Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@talisman](https://discourse.processing.org/u/talisman)
#### Post date: [July 16, 2018, 8:15pm UTC](https://discourse.processing.org/t/finding-pixels-inside-a-shape/1829/1 "2018-07-16T20:15:53Z")
Hi all ,
I have a ‘bouncing ball’ , of sorts . If you have followed Dan Shiffmans’ tutorials you must have encountered one. I want to show the underlying captured video only within the bouncing ball, like a spotlight.
I am attaching a pic showing the video and the circle .
Any hints into which direction to explore would be great.
Thanks Jonathan
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### Author:  [@jb4x](https://discourse.processing.org/u/jb4x)
#### Post date: [July 16, 2018, 8:19pm UTC](https://discourse.processing.org/t/finding-pixels-inside-a-shape/1829/2 "2018-07-16T20:19:15Z")
Have you tried the mask() function ?
[https://processing.org/reference/PImage\_mask\_.html](https://processing.org/reference/PImage_mask_.html)
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### Author:  [@talisman](https://discourse.processing.org/u/talisman)
#### Post date: [July 16, 2018, 8:26pm UTC](https://discourse.processing.org/t/finding-pixels-inside-a-shape/1829/3 "2018-07-16T20:26:39Z")
Thanks jb4X -
I am using p5.js - does not seem to have a mask .
If it did (or does and I missed it) : how would you go about it ? I think I need an image with the circle white and the rest black (masking part - right ?) and then move the image rather than the circle? Am I in the right direction?
Thanks again , Jonathan.
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### Author:  [@GoToLoop](https://discourse.processing.org/u/GoToLoop)
#### Post date: [July 16, 2018, 8:28pm UTC](https://discourse.processing.org/t/finding-pixels-inside-a-shape/1829/4 "2018-07-16T20:28:00Z")
[https://p5js.org/reference/#/p5.Image/mask](https://p5js.org/reference/#/p5.Image/mask)
[https://ThimbleProjects.org/gotoloop/97931/](https://ThimbleProjects.org/gotoloop/97931/)
[https://ThimbleProjects.org/gotoloop/97931/sketch.js](https://ThimbleProjects.org/gotoloop/97931/sketch.js)
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### Author:  [@jb4x](https://discourse.processing.org/u/jb4x)
#### Post date: [July 16, 2018, 8:30pm UTC](https://discourse.processing.org/t/finding-pixels-inside-a-shape/1829/5 "2018-07-16T20:30:53Z")
Ho sorry,
I didn’t see that you posted in the P5.js section.
I’m working with processing and assume that everyone is 😕
Anyway, the link that GoToLoop posted is the equivalent in P5.
For the rest you are on the right track I think 🙂