Center of mass/making one part of an object heavier

Help
1

Hi! :slight_smile:

What I am trying to achieve:

  • I have a human holding a staff (more or less from the center) with one hand.
  • I want the staff to feel heavy and that heavyness to be even more noticeable in the end of the staff.

I have tried two approaches, but since I just started learning, they are more likely not correct.
I tried first with basic shapes just to see if I was able to modify the staff behaviour and planning to attatch it to the human later on.

Attempt 1:

I tried to change the center of mass of the object.

  1. I created a cilinder and then assign (default settings)
  2. Created a triangle shape and then assign environment with default settings
  3. Set the density of the cilinder to 0
  4. Went to the attribute editor and in advanced tried to tweak the center of mass values

Nothing changed and the yellow dot that marks the center of mass did not move neither while tweaking the values.

Attempt2:

  1. I created a cilinder and a marker out of it
  2. I created a sphere and parent constrained it to the weapon mesh (the staff being the parent and the sphere the child)
  3. I created a marker for the ball through assign and connect
  4. I tried to modify the mass of the ball to make it heavier by setting density to 0 and adjusting the mass manually.

I did not see any result.

Do you know what way would be the most appropriate to achieve the desired result?

Thank you in advance!

(I just started checking the forum and you guys are doing an absolutely amazing job!!)

2

The first route is not currently possible, as the center of mass attribute is not plugged in, and will likely be removed in future releases.

Your second route is solid and recommended, as it’s both intuitive and visual.

But, instead of modifying Mass try modifying Density. Mass is automatically computed unless Density = 0 and there is rarely a reason to not automatically compute this. With a higher density, you should see the effect you want.

In fact, even without modifying density, you should still see the effect, given that the sphere adds weight towards the end of the staff.

And if you don’t need control over density of the ball, you can instead combine the two meshes into one. This would make the simulation more stable and give you the same effect. The weight could then be adjusted by tweaking the shape (total volume) of the sphere.