Draw 2D Chain

The Skeleton->Draw 2D Chain command in the Actor module allows you to create two-dimensional articulated/kinematic chains. There is no limit to the number of joints that can be included in a chain.

Tips for Drawing 2D Chains

For 2D chains, only the chain root and first joint rotate in three dimensions: the other joints are considered to be 2D objects when you invoke inverse kinematics. When you do this, the joints bend along one axis only, like an elbow joint.

When a 2D chain is drawn in a given window (such as the Front window), it is created in the local xy plane of the first joint defined and rotates about that local z-axis. The local x-axis always points to the origin of the next joint.

The way you create a chain defines its "preferred" angles. If you select the effector and drag it down, you will see the chain straighten out. Drag the effector up again to return to this angle.

For more information on skeletons, see the Skeletons section of the Modelling User's Guide.

Procedure

1. Choose the Skeleton->Draw 2D Chain command.
2. To create the first joint, click in any window.
   
   A null object (the chain root) is created with its local z-axis pointing "out" from the window. Joints need to be drawn in the window's plane (if you use the same window for drawing all chains).
   
   
3. Move the mouse cursor to a new position and click again to create the first joint.
   
   The null is now defined as the chain root, and the first joint is created.
   
   
4. Follow the instructions in the status line:

• To add joints, continue clicking to create as many joints as desired.
  
  Tip:
  
  You can rotate each newly created joint to a new position before the next joint is created, by holding the mouse button down and dragging the joint to the desired position.
  
  
• To start a new chain, middle-click. Move your cursor and begin another chain.

5. To end the drawing mode, right-click.

Last updated 02-apr-1998