Different gravity for different meshes

[PavolHejný]

Hi,
Can I somehow (with physics plugin Oimo.js) set different gravity for different meshes?
For example I want to simulate environment in water and I want to have there buoyancy.

https://www.babylonjs-playground.com/#2B84TV#7

Thanks a lot for your advice.

[Arte]

2 hours ago, PavolHejný said:

Hi,
Can I somehow (with physics plugin Oimo.js) set different gravity for different meshes?
For example I want to simulate environment in water and I want to have there buoyancy.

https://www.babylonjs-playground.com/#2B84TV#7

Thanks a lot for your advice.

I'm not guru on physics .

It might help you. https://www.babylonjs-playground.com/#2B84TV#8

[Pryme8]

Thats what mass is for (but I might be wrong)

 

if you wanted to be fancy https://www.babylonjs-playground.com/#2B84TV#12

[brianzinn]

for small objects (not counting ie: water/air resistance):
force = mass X gravity.

I made a small PG:
https://www.babylonjs-playground.com/#2B84TV#10
If the sphere mass and diameters are the same they bounce the same.  A bigger sphere with same mass does not bounce the same, so something else is being taken into account!

I thought then that if I made their density the same they would act more similar (in PG), so the physics engine must already do something, as they don't bounce the same from same start point.  There was a thread recently on physics friction with interesting comments.  Some engines have extra functionality - I tried the PG in Cannon.  I'm not aware of their being a way to explicitly set density for buoyancy. Maybe you can apply impulses with a vertical vector to influence the buoyancy.

[PavolHejný]

Thanks for every advice.

@Arte

Setting inital velocity is good and easy hack for some cases.

@brianzinn

I think that is exactly the problem of Oimo. Oimo is physics in vaccum - everythink is falling with same acceleration.

@Pryme8

Perfect hack!