Create Chain

Author: Dirk Bialluch
Copyright 2000-2009, Lightstorm3D

Create Chain V2.0
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Description

This tool creates an animatable chain that is build along a nurbs path using a single or two different link objects. The number of links required to cover the complete nurbs path with elements can be computed by the script. It also provides an approximation method to estimate a scale factor so the complete path is covered with link elements. Since this is just a rough estimation you can tune the scale factor afterwards by using the jointScale attribute on the spline IK handle node.

Sample Movie using nurbs curves driven by Maya hair

Function Summary

• 1 or 2 different link objects
• link length per object
• scale links uniformly or just along path to fit path curve arc length
• global link scale attribute on spline IK handle
• compute number of links to cover whole path
• set fixed number of links
• rebuild path curve uniformly with given number of spans
• animate chain along path
• individual and successive link rotation around path tangent vector
• create instances or real shape copies

Usage

Command: lsCreateChain

When using this tool you have to follow some basic rules how to set up the link element(s).

Once you have created the geometric elements used as link objects you have to choose two points used as rotation pivots, one point at the beginning of the link and on at the end. Links are set up along Maya's world x-axis. Position the links so the first rotation point is located at the world space origin and the second is on the positive side of the x-axis. Move both the pivot of the link objects to world space origin and freeze the transformation.

Next you need to figure out the distance between both rotation points. You can use Maya's measure tools or just estimate the value using the grid. In the example above the first smaller link has a rotation point distance of 0.75 and the second larger one 2.0. Enter these values in the Create Chain option window under "Link 1 Length" and "Link 2 Length". This tells the script how long each joint in the spline IK chain will be.

In the example shown above the links have already been rotated about the x-axis before freezing the transformation to form a proper chain of rings. Using "Link 1 Rotation", "Link 2 Rotation" and/or "Successive Rotation" you can control this rotation within the UI. When using a single link you may want to use 90 degree successive rotation so each following link is rotated by 90 degree about the local x-axis (path tangent vector).

User Interface Screenshots
(screenshots might not reflect latest version)

Creation UI