# \[F8\] sonar, circles, hittest, and actionscript

**URL:** <https://forum.kirupa.com/t/f8-sonar-circles-hittest-and-actionscript/210244>\
**Category:** flash\
**Created:** [December 16, 2006, 5:29pm UTC](https://forum.kirupa.com/t/f8-sonar-circles-hittest-and-actionscript/210244 "2006-12-16T17:29:54Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![steve\_b](https://avatars.discourse-cdn.com/v4/letter/s/ee7513/32.png) [@steve\_b](https://forum.kirupa.com/u/steve_b)\
**Post date:** [December 16, 2006, 5:29pm UTC](https://forum.kirupa.com/t/f8-sonar-circles-hittest-and-actionscript/210244/1 "2006-12-16T17:29:54Z")

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I need to make a “sonar” effect in actionscript, but am encountering a whole host of problems, was wondering if anyone can help!

The sonar is an expanding circle from a centre point. I need to make the circle and the expansion happen in actionscript so that the size and speed can be varied. Is there a simple plug and play method of doing this?

Being a sonar, it needs collision detection objects within its expanding circle. Can this be done using the shapeflag method of hitTest?

Thanks,

Steve