• 1st path, 2nd path (rails) - Select the first and second path curve. You can use wireframe curves, face edges, sketches, curve lists or parting lines. The rails can also form part of a cylinder or cone.

• Profiles - Select one or more cross-section profiles and then middle-click to continue. Again, wireframe curves, face edges, sketches, or parting lines are supported.

 

 

 

Spine

Use this option to control the Z axis direction of the loft. Choose from the following options:

 

• None - No spine curve is used. The loft will continue to the endpoints of both drive curves.

• Natural - A straight line spine is used if all of profiles are in parallel planes. If not, a simple spine perpendicular to each of the profile planes through the centroid of the profile is used. No additional inputs are required.

• Spine - The Z axis remains tangent to a spine curve. The spine curve can be any existing curve or face edge. Use the Curve option below to select the spine curve or face edge.

• Parallel - The Z axis remains perpendicular to an existing plane. This forces the profile plane to remain parallel with the existing plane. Use the Plane option below to select the normal vector of the parallel plane.

 

Curve

Select the spine. It can be a wireframe curve, face edge, sketch, curve list or parting line.  This option is used with the Spine / Spine option above.

 

Plane

Select the normal vector of the parallel plane. This option is use with the Spine / Parallel option above.

 

Blending

Use this option to specify how the loft should be blended between multiple profiles. Select from the following:

 

• Linear - The face includes a linear blend between profiles.

• Smooth - The face is blended smoothly between profiles.

 

Modify Influence

This refers to a factor that determines a profile's influence relative to its neighbors. By default all profiles have an influence factor or 1. Setting an influence factor to 2 gives that profile twice as much influence as its neighbors. This roughly means that the cross section half way between the profiles will be 2 parts of one profile and 1 part of the other.

 

Because the only thing that matters is the ratio of influence factors, the range of the factor (other than they have to be positive) is not limited. However, once the ratio gets larger than about 10, there's really not much difference at all in the loft that is created.

 

Maintain Profile Height

Check this box to scale the profiles only in the X direction, maintaining their Y direction (height) as they are sized to fit between the 2 rails.  If not checked, profiles will be scaled in both directions.  The X and Y directions refer to the line connecting the two rails and do not relate to the coordinate system of the profiles.

 

 

 

This tab contains options for creating, modifying and deleting connection lines and tangent vertices.  Connection lines are used to match profiles during the Bi-RailLoft Face commend.  Note that is you escape from this commend, all connection lines you create will be undone.

 

Auto

Use this option to create a set of default connection lines. This option along with the loft echo will allow you to preview how the profiles will be matched during a standard loft command (without connection lines).

 

Sometimes such a preview will alert you to problems that the loft may encounter while attempting to match the profiles. The figure blow illustrates such a case. Using the Add option to create a single loft connection line here will correctly match the profiles.

 

Default Loft Connection Lines Indicating a Matching Problem

 

Add

Use this option to add a single loft connection line.
 

• Select a connecting point from one of the profiles.
   

The profiles will be analyzed and a connection line will be created that passes through the connecting point selected.

 

Modify

Use this option to modify a loft connection line by moving one of its connection points.
 

1. Select a connection line to modify.

2. Select a new connection point.
    

The connection point will be moved to the new location. If the connection point does not move try deleting, other connection lines that may be interfering with the move.

 

Delete

Select a loft connection line to delete.

 

Use Tangent Vertices

Check this box if you want to use tangent vertices on sketched profiles. If this option is not checked, the lofted faces will span across tangent vertices as shown in the figure below.

 

 

 

 

• During steps 1 and 2 above you can right-click and select Make Curve List from the Input Options Menu. This will allow you to make a parametric list of existing curves to use as input for this command.