Controlling a Joint Procedurally¶
Sometimes one wishes to procedurally take control of a model’s joint. For
example, if you wish to force a character model’s eyes to follow the mouse,
you will need to procedurally take control of the neck and head. To achieve
myNodePath = actor.controlJoint(None, "modelRoot", "Joint Name")
This creates a dummy node. Every frame, the transform is copied from the dummy
node into the joint. By setting the transform of the dummy node, you can control
the joint. Normally, one would want to use
set_hpr() to rotate
the joint without moving it. The dummy node is initialized in such a way that
the joint is in its default location, the one specified in the model’s egg file.
You must store a local (not global) transform in the dummy node. In other words, the transform is relative to the joint’s parent bone. If you are controlling the forearm of a model, for instance, the transform will be relative to the upperarm.
The string “modelRoot” represents the name of the model node - the string “modelRoot” is usually the correct value.
The string “Joint Name” represents the name of the joint. Typically it would be
something like “Femur”, or “Neck”, or “L Finger1”. This is usually set inside
the modeling package. For example, in MAX, each object in the scene has a name,
including the bones. If necessary, you can determine the joint names by scanning
the egg file for strings like
<Joint> Femur. You can also use the call
actor.listJoints() to show the
complete hierarchy of joints.