Legacy Reference

Joint Attachments

Joint attachments require an attachment socket that provides a connection point between the attachment and the character. Use the move and rotate tool to position and orient the socket relative to a bone joint.

The socket is attached to a joint and moves with the joint when the skeleton is animated. Secondary animations can be enabled on a socket and provide additional motions based on a real-world physical simulation and generated in response to the movements of the character. This has the effect of making loosely-attached objects behave more realistically when the character is undertaking fast movements.

These secondary animations can also be redirected to the skeleton of the character to apply the simulated motion to all vertices that are part of the skinned mesh and weighted to the joint. This is very useful when animating hair and cloth. By enabling collision detection, such attachments can also interact with the character.

You can simulate the motion of hair braids and dangling straps using joint attachments. A chain or rope of pendula can be created by attaching a pendulum at each link. When the motion simulation is activated, each parent joint transfers motion to the children. In this case, the primary motion is not coming from an animation, but from a previous motion simulation. Collision detection and response is used to limit the motion of the attachment from moving through the body of the character.

To create a joint attachment

  1. In Geppetto, in the Properties panel, click the number next to Attachments and Add or Insert.

  2. For Name, enter a name for the attachment.

  3. For Type, choose Joint Attachment.

  4. For Joint, choose the bone icon, then open the applicable joint to place the socket on.

  5. For Geometry, choose the folder icon and select the desired *.cgf file for the attachment.

  6. For Material, choose the folder icon and select the desired *.mtl file for the attachment.

  7. Adjust the values of attachment parameters for the desired result, as listed in the following table.

Joint Attachment Parameters

Parameter Description
View Distance Multiplier Multiplier to the computed fade-out camera distance to apply on the attachment.
Store Position Stores position data relative to either the character or to a joint.
Store Rotation Stores rotation data relative to either the character or to a joint.
Transform Transform-Translation (T) and Rotation (R) vectors for the X, Y, and Z axes in relation to Store Position and Rotation.
Simulation Type of simulated motion. Disabled is on by default, but types consist of: Pendulum Cone, Pendulum Hinge, Pendulum Half Cone, Spring Ellipsoid, and Translational Projection. For more information, see Secondary Animations (Simulations).
Hidden Hides the attachment.
Physicalized Rays Enables hit ray detection if a physics proxy is available.
Physicalized Collisions Enables collision detection if a physics proxy is available.