# Cannon physics: possible bug in alpha.17

**URL:** <https://forum.babylonjs.com/t/cannon-physics-possible-bug-in-alpha-17/11083>\
**Category:** Bugs\
**Created:** [May 23, 2020, 6:52pm UTC](https://forum.babylonjs.com/t/cannon-physics-possible-bug-in-alpha-17/11083 "2020-05-23T18:52:36Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![holger](https://avatars.discourse-cdn.com/v4/letter/h/ed8c4c/32.png) [@holger](https://forum.babylonjs.com/u/holger)\
**Post date:** [May 23, 2020, 6:52pm UTC](https://forum.babylonjs.com/t/cannon-physics-possible-bug-in-alpha-17/11083/1 "2020-05-23T18:52:36Z")

</div>

Hi Folks,

this playground [https://www.babylonjs-playground.com/#9QQ97W#1](https://www.babylonjs-playground.com/#9QQ97W#1) doesn’t work with cannon physics and current latest (v4.2.0-alpha.17). It seems that the ground-plane gets rotated when assigning the impostor. If you switch to 4.1.0 it works fine. On my local dev-environment it even works with v4.2.0-alpha.16.  
I’ve noticed there was a commit to cannon plugin `src/Physics/Plugins/cannonJSPlugin.ts` a couple of days ago maybe this has something to do with this issue.  
Regards

---

<div class="post-metadata">

**Author:** ![RaananW](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/raananw/32/28955_2.png) [@RaananW](https://forum.babylonjs.com/u/RaananW)\
**Post date:** [May 23, 2020, 7:16pm UTC](https://forum.babylonjs.com/t/cannon-physics-possible-bug-in-alpha-17/11083/2 "2020-05-23T19:16:21Z")

</div>

Seems to be an issue with the view of the plane impostor. Di dyou really mean to use plane impostor? The box impostor is usually much more suitable:

[https://www.babylonjs-playground.com/#9QQ97W#2](https://www.babylonjs-playground.com/#9QQ97W#2)

I will check the issue with the plane impostor very soon

---

<div class="post-metadata">

**Author:** ![holger](https://avatars.discourse-cdn.com/v4/letter/h/ed8c4c/32.png) [@holger](https://forum.babylonjs.com/u/holger)\
**Post date:** [May 23, 2020, 7:24pm UTC](https://forum.babylonjs.com/t/cannon-physics-possible-bug-in-alpha-17/11083/3 "2020-05-23T19:24:48Z")

</div>

Thanks for the quick response 🙂

> [@RaananW](#):
>
> Di dyou really mean to use plane impostor

I used PlaneImpostor only for the sake of simplicity to demonstrate the issue. This problem seems to exist also for HeightMapImpostor

---

<div class="post-metadata">

**Author:** ![RaananW](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/raananw/32/28955_2.png) [@RaananW](https://forum.babylonjs.com/u/RaananW)\
**Post date:** [May 23, 2020, 7:26pm UTC](https://forum.babylonjs.com/t/cannon-physics-possible-bug-in-alpha-17/11083/4 "2020-05-23T19:26:38Z")

</div>

yes, the transformation is applied incorrectly on first frame. Working on fixing that 🙂