# Null Engine collision detection

**URL:** <https://forum.babylonjs.com/t/null-engine-collision-detection/26501>\
**Category:** Questions\
**Created:** [January 6, 2022, 5:40am UTC](https://forum.babylonjs.com/t/null-engine-collision-detection/26501 "2022-01-06T05:40:16Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![trigangle](https://avatars.discourse-cdn.com/v4/letter/t/e5b9ba/32.png) [@trigangle](https://forum.babylonjs.com/u/trigangle)\
**Post date:** [January 6, 2022, 5:40am UTC](https://forum.babylonjs.com/t/null-engine-collision-detection/26501/1 "2022-01-06T05:40:16Z")

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For the null engine, do I need to run scene.render()? I am only going to be using it for collision checking and never for any form of animation.

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**Author:** ![sebavan](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/sebavan/32/57_2.png) [@sebavan](https://forum.babylonjs.com/u/sebavan)\
**Post date:** [January 6, 2022, 9:30am UTC](https://forum.babylonjs.com/t/null-engine-collision-detection/26501/2 "2022-01-06T09:30:39Z")

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Yup you need to call into it as this will trigger all our internal process making collision detection and such.

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**Author:** ![Raggar](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/raggar/32/20672_2.png) [@Raggar](https://forum.babylonjs.com/u/Raggar)\
**Post date:** [January 6, 2022, 1:35pm UTC](https://forum.babylonjs.com/t/null-engine-collision-detection/26501/3 "2022-01-06T13:35:40Z")

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Perhaps you can call it _automatically_ as well - I meant **manually**

> <https://github.com/BabylonJS/Babylon.js/blob/53e0dadc4bad91a11b2203766b1de8ac34912a77/src/scene.ts#L4126>

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**Author:** ![trigangle](https://avatars.discourse-cdn.com/v4/letter/t/e5b9ba/32.png) [@trigangle](https://forum.babylonjs.com/u/trigangle)\
**Post date:** [January 7, 2022, 12:41am UTC](https://forum.babylonjs.com/t/null-engine-collision-detection/26501/4 "2022-01-07T00:41:03Z")

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So do I need to call it whenever a meshes position is changed, or only when the scene is initially created?

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**Author:** ![sebavan](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/sebavan/32/57_2.png) [@sebavan](https://forum.babylonjs.com/u/sebavan)\
**Post date:** [January 7, 2022, 1:13pm UTC](https://forum.babylonjs.com/t/null-engine-collision-detection/26501/5 "2022-01-07T13:13:49Z")

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whenever something changes is probably fine

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**Author:** ![carolhmj](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/carolhmj/32/25918_2.png) [@carolhmj](https://forum.babylonjs.com/u/carolhmj)\
**Post date:** [February 4, 2022, 5:11pm UTC](https://forum.babylonjs.com/t/null-engine-collision-detection/26501/6 "2022-02-04T17:11:52Z")

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Hi @trigangle just checking in, do you have any further questions? 😄