Rail Clone Tool

The Rail Clone command (Multiply > Duplicate > Rail Clone) works just like the Rail Extrude command, however, instead of resulting in an object with a smooth skin, it creates skinless segment clones along the background curve(s).

Rail Clone will create clone or clones of a point, polygon, or object along a curved path (single rail clone) or multiple paths (multiple rail clone). It is nearly identical to the Rail Extrude command. The difference is that Rail Clone creates individual copies of the object instead of forming a continuous skin for the object.

The curve(s) must be in the background layer and the polygons must be cloned in the foreground layer. The orientation and position of the foreground polygons will affect the result. Generally, they should be at the very beginning of the curve and oriented perpendicular to it - as if the curve was a thread you were threading through the polygons.

The direction that the curve faces (which end is considered the beginning) will have bearing on both the shape and direction of the cloning. If you don’t get the results you expect, try flipping the curve’s starting point with Detail > Flip. If you are using multiple curves, they should generally run in the same direction.

Single Curve

The Rail Clone: Single dialog will appear when a single curve is in the background.

Segments is the number of clones in the resulting object. Select Automatic to distribute a number of clones along the rail curve (based on the Curve Divisions setting on the General Options Panel) according to the curve’s knot (point) spacing.

Select Uniform Lengths to distribute some number of clones (which you specify) evenly along the length of the entire curve. No matter what the knot spacing is, the clones will remain evenly spaced.

Select Uniform Knots to distribute some number of clones (which you specify) evenly between the knots that make up the curve. Whether the knots are close together or far apart, there will be the same number of segments between each.

Oriented determines the orientation of the polygon template as it follows the curved path. When active, it causes all clones to angle themselves automatically so that they are aligned with the rail curve as it turns. When inactive, it causes all clones to remain in the same orientation as the template so that they face exactly the same way.

Multiple Curves

The Rail Clone: Multiple dialog will appear when multiple curves are in the background.

In practice, one curve will act as the main cloning curve and the other(s) act as shaping curves. The effect of the shaping curves is determined by the distance from the main curve. However, you may change the effect by moving the polygons closer or farther away from any of the curves.

Segments is the number of clones in the resulting object. Select Automatic to distribute a number of clones along the rail curve, based on the Curve Divisions setting on the General Options Panel. If you also select Knot, clones are distributed with regard to the curve’s knot (point) spacing. If you use Length, knot spacing is disregarded.

To specify the number of clones, choose Uniform and enter the number in the input field. If Length is also active, the clones will remain evenly spaced no matter what the knot spacing is. If you use Knot instead, there will be the same number of clones between each knot, no matter how close together or far apart they are.

Strength determines how strongly the rails vie for control of the point locations. You will not notice much of a difference unless you have Scaling (below) deselected. The higher the Strength value, the closer the object will hug the rails.

Oriented determines the orientation of the polygon template as it follows the curved path. When active, it causes all segments to angle themselves automatically so that they are aligned with the rail curve as it turns. When inactive, it causes all clones to remain in the same orientation as the template so that they face exactly the same way.

Scaling determines how clones along an axis are sized. If the rails in the background layer spread apart along any axis or axes, then the clones will automatically stretch along those axes as well.

Turn Scaling on to scale clones equally, rather than along those specific axes only.

For example, with Scaling off, if you Rail Clone a polygon along the Z axis using two rails that spread further apart in the X axis, the clone’s copies will be stretched on the X axis to maintain their relationship to the guide rails.