Problem : Mesh is self transformation when use parent child and physics

[atallah salah]

Hello every one,
I'm working on a project and I'm using physics and collision and everything was fine until I start using parent child for object and meshes
i create an example here show some issue  :
https://www.babylonjs-playground.com/#JUKXQD#70

you can see in the example :
box position still increasing in y Axis and the same happen for the highest skull

Thank you for help

[trevordev]

Are you looking for it to look like this? https://www.babylonjs-playground.com/#JUKXQD#71

If you use addChild instead of parent =, world position should not change

[atallah salah]

@trevordev Thank you for this answer it's was really helpful it's solve other topic for me
in the example you have send it's still the same problem if you can focus on the third skull and box they still incensing position on y Axis , it's take i while to check it
if you check it after 1 minute when the parents functions done sure you will see the difference

Thank you

[trevordev]

Sorry, I misunderstood. Parenting with physics has documented issues when the parent also has an impostor see https://doc.babylonjs.com/how_to/using_advanced_physics_features#ignoreparent. This seems to a limitation with the current physics engines.

[atallah salah]

@trevordev Thank you for answer

I tried to use ignoreparent in impostor but still the same problem .
Do you think there is a solution for this problem  ?

[trevordev]

Could you share more about your use case? Why do you require parenting? Is this what you are trying to do? https://playground.babylonjs.com/#PRHF00#6

[atallah salah]

@trevordev

My cases is about drawing object and this object have to detect all other objects collision in the scene

I have to use imported meshes cuz it's not possible to draw it in BabylonJS
Parenting used for some controls like animation and change parent position or rotation and children have to do the same

In my case I must use parenting  , I try to use method like RegisterBeforeRender to set position but it's was very heavy cuz the number of objects and movements at the same time

The all idea depending on parenting  and collision

I was thinking about if I could stop use parenting  at the point I use collision  and use it again  when done with collision if that possible what do you think ?
I try to use Oimo.js in Babylon but still same
Thank you for your answer

[trevordev]

@atallah salah Yea,  for your use case, if parenting is only used to setup the scene only disabling parenting when needing to run physics sounds like a good solution. 

[atallah salah]

@trevordev

I try this way, it's work fine with some issue and that was great, but still can't use both on the same time do you think BabylonJS going to update or fix this ?

[trevordev]

Yea, I'm currently investigating a couple physics issues, trying to make some more examples and trying to add ammoJS physics engine support to Babylon.

I also came across another playground which has parenting which works for a car which you could take a look at https://www.babylonjs-playground.com/#UGMIH#15

[atallah salah]

@trevordev
This is a great example not use parenting at all

In my case user will able to add object to another object  to be transforming together like what parenting do at the same time have chain(sphere connected together using Joint ) and this chain have to use physics all the time scene running
I have at least 40 object user have to put it on each other and maximum 100 object 
when using physics collision and parting with BabylonJS object (Box,Sphere,..) everything work fine but not for the imported mesh

do I can link object with each other like parenting with with using physics link
I will try the example

Thank you