# Gravity, physics, and armatures

Well, I’m trying to learn how to use the game engine but I’ve run into a bit of an obstacle. I just created a character and wanted him to be subject to gravity when I run the game. I selected the mesh and gave it a rigid body for its physics, I also set it as an actor and turned on collisions. When I ran the game nothing happened, the figure remained floating in space several feet above the ground. I guessed it was probably because the mesh had an armature for a parent and it couldn’t move without it, so I gave the same physics settings to the armature. Now when I run the game the mesh moves, but it spins wildly and then flings off to the side instead of just falling down to the ground. What am I missing?

I would start with disabling the physices for the mesh. You usually run into problems when you have a physics volume spawning inside another physics volume.

Red’s correct. A general idea of how your character setup should look is:

Mesh (No Collision) Parented to Armature (No Collision) Parented to Collision Mesh (should probably just be a box; also should probably be Dynamic, and not Rigid Body, since rigid body physics means objects can tip over).

Ah, that works. For my collision mesh I just used an empty so that it didn’t make an unwanted box moving around with my character. Thank you.

You can as well set Objects invisible in the Pysics Tab, which is likely for, as in this Case, the Collision Box.
I don’t think an Empty will be a good Idea – even if you can give it a Box Collision, the Dimensions are the same to all Sides – an organic/anthropomorphic Character will be likely to be taller than wide.

… what a sloppy Expression of Mine…

The problem with empties is they can’t detect collisions as they do not have a mesh.
The same with armatures.

if the armature is dynamic can set the radius for the collision .

this way , can avoid having the cage (box)

of course the radius not ever work well