Setting up a rifle to be parent of hands & child of shoulder?

#1

Coming from a Max/Maya background, I’m kind of a noob to MotionBuilder but I’m a veteran of the search function and it’s come up empty for me. Here’s what I want to do:

1)Link both hands to a rifle(done and working)
2)Control the rifle with a right hand auxiliary effector placed at the end of the rifle stock, against the shoulder (done and working)
3)Have the rifle constrained as a child of the control rig’s right shoulder so it it moves/rotates with the character while remaining against his shoulder (MB explodes)

I have attempted a few different methods and I have it pretty much working by having the rightWristEffectorAux on a parent/child constraint to the right shoulder. The problem is that the WristAux effector doesn’t seem to be keyable within a take, and if I move it it is moved in all takes. It always stays where I move it, regardless of timeline or take (so no, it’s not locked).

What’s strangely noteworthy is that the left hand on the gun’s foregrip is animating within the take and across takes, following how the right wrist effector is keyed. But the effector itself (including the right hand and the gun) are not moving or rotating.

Is this a bug I’ve found or am I doing this totally wrong?

#2

have you tried just making the right hand aux effector a child of the shoulder?

you could also do this with a Handle object that controls the effector but places its pivot at the shoulder…

set up a separate rig for the gun that then gets parented under the effectors… like a basic ik constraint for the gun so that it pivots from the shoulder point and Aims at the hand aux.

There are limits to even Motionbuilders ability to double solve the rig to avoid cycles… you could also look at the multi-reference constraint to create a rig that lets you contorl the gun from what ever object you select … and base it on that pivot…

we cover lots of this in our DVD , see my sig. link if you find you need to do a lot of rigging in mobu… its for some one just like your self, maya/max guy that is good with search now in motionbuilder land.

#3

Thanks for the suggestions. One of the guys at my office sorted it out by constraining a null… thingie to the chest, parenting another null to that then constraining the right wrist effector to the 2nd null. I don’t know if that’s the cleanest solution but it’s working great. I hadn’t even thought to use any actual parenting in the setup but it looks like that was the way to go.

I was looking at picking up your DVD last week actually but it’s still not clear the extent of MB work I’ll be doing yet. Thanks again.

#4

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