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Maya pivot point vs CoM

So I created a sub hull in blender using a mirror modifier so the hull is mirrored then to get an alpha out the door i added 2 screws (boat propellers) and 4 planes (fins) onto it from an old model, I centered them close, but not perfectly. Then I rigged it and exported it to .fbx

No matter what, it was causing us issues in UE4. So I opened .fbx into Maya deleted the old bones and joints and skins and then I took the hull mesh (since I know its a perfect mirror along the x (length) and in Maya went Modify -> Center Pivot. Im not a Maya user but I was told this sets it to the center of geometry.
I took note of where this moved the mesh (the new translate value it gave me, everything was 0,0,0 before, values were x 531.711, y 0.663, z 2.199) which makes sense cause before all this, in Blender, I had moved the pivot point 0.662 cm along the y on instruction from my partner.

I then made sure that the pivot-point was at the grid origin (0,0,0) which I’m pretty sure it was and double checked by turning on grid snapping and snapping the pivot point ([INSERT] to move pivot point I was told) to the grid center.

I then moved the pivot point of the rest of the meshes by selecting them pressing [INS] and snapping it to grid center as well as moving the root joint the values I noted above and it all lined up. I zeroes out all the meshes transforms at this point and reskinned the meshes to their respective bones and exported it.

Now when I bring it into Unreal, delete every collider attached the the bones and then add a basic cube to the root bone to envelop the entire mesh. When I hit play I get the center of mass values of x=133.800, y=-0.551, z295.895

My partner made a cube the same size in Maya with a smaller cube above it to represent the sail (superstructure/bridge) and it prints 0,0,0 for it.

What could possibly be wrong? I can send the FBX or .mb or .blend or unreal project files if it helps (in an empty project and without any textures obviously). Theres gotta be a way to zero out the COM because of the slight offset in the y especially it moves in a slight diagonal when I try to move it straight forward

This is the setup, every mesh component plus the root joint is located exactly where you see the translate widget, which is the grid center.

Thanks.

Edit: Could it be because my spine bones (bones that are just used to get the joints into poisint not at the origin, only the root joint is at the orign let me attach two pics.

Sorry about the width, tried to cut it as small as possible, all my meshes + my root bone selected showing them all at the same pivot point at the oirigin and my rig below it with the origin of one spine bone for example.

Got some info found it. It depends on the body. My partners sub sized cube had a COM of 0 because his physics body in the physics_asset was perfectly bound to all 6 verts. I have to manually set mine. So I used the center of mass offset and while it didnt read the proper CoM it drove straighter so it must be working (UE4 bug?)