For the next part of my attempt to recreate the Matrix Lobby Shootout in MotionBuilder, we come to two-handed props.
Animating 2 handed weapons and prop interaction is something that you do a lot in mocap. As I mention in the video, unless your performer and character are exactly the same size, their hands are going to be in different positions which means your character will no longer be holding the prop correctly in the mocap. Sometimes, even if your performer and character are exactly the same size, or even the same person, there can still be slight offsets that will need adjusting.
So, in this video we’ll look at how to improve on a simple Parent/Child Constraint to create realistic prop interactions and avoid that unnatural looking “glued-on” effect that can ruin the believability of your animation.
We’ll also look at how to use the Pose Controls to create and apply finger poses to different character rigs, even if they’re not in the same file.
And last, but not least, we’ll set up a Relations Constraint to recreate the hand-held feeling of the camera person running with the SWAT team in the opening shot
A Parent/Child constraint lets you connect any two objects without affecting their existing hierarchies.
For example, in the video, the SWAT character’s wrist effector is set as the “Parent” or “Source” object and the gun is set to the “Child” or “Constrained object”. Once the constraint is “active”, the gun object will follow to hand as it moves.
The only problem with this is, sometimes this locked position can create some very unnatural looking animation. The child object looks like it’s glued to the parent object. In this example, the character’s left wrist is set as the “child” of the “parent” gun object. While this position works while the character is carrying the weapon, it begins to look broken and unnatural when the character lifts the gun to take aim.
To fix this, I’ll show you how you can animate the properties on the Parent/Child constraint so the gun looks like it’s moving in the hand, rather than being stuck to it.
The Pose Controls create a snapshot of the characters pose. This can include everything from the entire body to just the fingers.
As poses are created and applied using the Control Rig, you can paste a pose on to any character that has a Control Rig. Libraries of poses can then be saved and merged into different files allowing you to use the same poses on different characters in different files.
Relations constraints let you create a “relation” between animatable properties on 2 or more objects. The relation between the objects is created using a plug-and-play style graphical interface, called the Relations pane.
Objects are dragged from your scene into the Relations pane and set as “Sender” or “Reciever”. Outputs from the “Sender” object can then be connected to the inputs on the “Receiver” object to transmit the data. This gives you control of exactly what output is connected to which input. Where things get really interesting is that between those connections, you can add mathmatical operators between the objects to create very specific actions.
For example, in this video we’ll connect the translate Y value from a characters hips (sender) to the translate Y value on the camera (reciever) and offset it’s position and reduce the motion using a couple of the mathmatical operators.