[Physics] How to change center of mass?

Hi,

My collision box is set to Bounding Box(it's what I need it to be).

That means the center of mass is in the center.

How do I change the center of mass to the bottom of the object?

There's no simple way of doing this but you could create a custom collision polygon where it is hollow near the top, so most of the mass is at the base.

you could also experiment with using distance/revolute joints to pin a tiny sprite 1*1, with super high density to wherever you want to add mass on the bigger object

The C.O.M. is based on the collision mask, so by making it bottom heavy, but setting the Physics:Collision mask property to Bounding Box, you should be able to get the effect you want.

blackhornet

it needs to be set to collision polygon.. bounding box just puts COM back in middle

Hmm, unfortunate.

keepee

Issue is i need the object to collide at the Bounding Box, by game design. So a Custom collision polygon doesn't work for me.

I'll try the thing with a tiny invisible superheavy sprite attached to the bottom of the object, see if that helps : )

Xionor

I meant something like this:

https://dl.dropboxusercontent.com/u/53374990/Pics/bottomheavycollisionpolygon.png

I tested it and it works.. you can jump on top of it and you don't fall through or anything, it acts just like a bottom heavy box

also it's a vending machine.. so it suits :D

only problem is it's >8 polygon points, so the image editor will understandably nag you every point you add above 8

keepee

Wow 0.o That's genius!!

I'd never have thought of that solution and didn't even consider you could make dents like that in collision boxes. This should be put in a tutorial or something! : o

Thank you a ton!