# Polygon Intersection

**URL:** <https://community.cesium.com/t/polygon-intersection/7147>\
**Category:** CesiumJS\
**Created:** [July 11, 2018, 5:48pm UTC](https://community.cesium.com/t/polygon-intersection/7147 "2018-07-11T17:48:27Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Brian\_Behling](https://avatars.discourse-cdn.com/v4/letter/b/a88e57/32.png) [@Brian\_Behling](https://community.cesium.com/u/Brian_Behling)\
**Post date:** [July 11, 2018, 5:48pm UTC](https://community.cesium.com/t/polygon-intersection/7147/1 "2018-07-11T17:48:27Z")

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Hello.

Is there a Cesium way to determine when a mouse cursor is inside a polygon entity?

I can accomplish with this with some 3rd party libraries, but just curious if this can be done using only the Cesium library.

Thanks

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**Author:** ![omar](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/omar/32/1999_2.png) [@omar](https://community.cesium.com/u/omar)\
**Post date:** [July 11, 2018, 8:04pm UTC](https://community.cesium.com/t/polygon-intersection/7147/2 "2018-07-11T20:04:16Z")

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Hey Brian!

Do you mean, given a 3D position, you want to find out if it’s inside a particular polygon? Or do you mean given a screen position, you want to find out if a polygon is under that? For the latter, check out the [drillPick](https://cesiumjs.org/Cesium/Build/Documentation/Scene.html#drillPick)and [pick](https://cesiumjs.org/Cesium/Build/Documentation/Scene.html#pick) functions.

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**Author:** ![Gabby\_Getz](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/gabby_getz/32/7838_2.png) [@Gabby\_Getz](https://community.cesium.com/u/Gabby_Getz)\
**Post date:** [July 12, 2018, 2:00pm UTC](https://community.cesium.com/t/polygon-intersection/7147/3 "2018-07-12T14:00:59Z")

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For some examples, checkout the [Picking Sandcastle demo](https://cesiumjs.org/Cesium/Build/Apps/Sandcastle/index.html?src=Picking.html).