Drive
Curve Loft Face 
Insert 
Shapes (Advanced) (Part Level)
Use this command to create a shape by lofting
(blending) faces through a series of profiles. The profiles can be sketches,
wireframe curves, curve lists, or face edges. Unlike the Loft Shape command, this command uses a drive curve
and includes options that are similar to the Sweep Shape command.
The required inputs include the profiles to
loft and the drive curve. The optional inputs are numerous. They include
connection lines, orientation, scale, twist, profile blending and end
caps.
When lofting with a tangentially closed drive curve, the
first profile is automatically connected to the last profile. To create
a surface which is different at the start and end of the drive curve,
place multiple profiles at the joint.
Drive Curve - Select the drive curve. You can use wireframe curves, face edges, sketches, curve lists or parting lines.
Profiles - Select the profiles to loft. Again, wireframe curves, face edges, sketches, or parting lines are supported.
Z-Spine
Use this option to control the Z axis direction of the loft. Choose from the following options:
Natural - A straight line is used if all of the 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 curve or face edge. This option is used with the Z-Spine / Spine option above. You can use wireframe curves, face edges, sketches, curve lists or parting lines.
Plane
Select the normal vector of the parallel plane. This option is use with the Z-Spine / Parallel option above.
X-Orient
Use this option to control the orientation of the X axis of the loft. Choose from the following options:
Natural - The X axis is constrained to minimum rotation. No additional input is required.
Guide Plane - The X axis stays "in" an existing plane. It is perpendicular to the plane normal. Use the Plane option below to select the normal vector that defines the direction of the guide plane.
X-axis Curve - The X axis is projected and follows the intersection of an existing curve or face edge. Use the Curve option below to select the X axis curve or face edge.
Plane
Select the normal vector that defines the direction of the guide plane. This option is use with the X-Orient / Guide Plane option above.
Curve
Select the X axis curve or face edge. This option is use with the X-Orient / X-axis Curve 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.
End caps
Use this option to control the placement of end cap faces on the start and end of shapes. This option can automatically form closed volumes when a closed profile is used or when an open profile with the Boundary option is used.
This tab contains options for creating, modifying and deleting
connection lines and tangent vertices. Connection
lines are used to match profiles during the Drive Curve Loft 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.
Select a connection line to modify.
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.
Scale/Twist
Use this option to apply a scale or twist attributes to the loft. Select from the following option:
None - No scale/twist is applied.
Linear - The scale/twist factor is applied as a linear uniform function starting and ending at the values you specify on this tab.
Variable - The scale/twist factor is applied non-uniformly based on scale/twist attributes attached to the drive curve (see above) using the Add, Modify, and Delete buttons discussed below. The scale/twist factor will match the attribute value at that point on the drive curve and blend smoothly between attributes.
If only one attribute is placed on the drive curve, the entire loft will be scaled or twisted to that value. If no attribute is placed at the start and/or the end of the drive curve, the loft will continue to remain tangent to the previous blend segment
Add
Add a scale/twist attribute to the drive curve. This option is used with the Scale or Twist/Variable option above.
Select a point on the curve to locate the attribute.
Enter the scale/twist factor.
Repeat steps 1 and 2 until all scale/twist attributes are added and then middle-click to continue.
Scale Type
Specify the axes along which the scaling should occur. Select one of the following: Uniform, X only,Y only and Z only. This option is used with the Scale/Variable/Add option above.
Flat
Use this option to mix constant and variable scale/twist attributes along the drive curve. Just place scale/twist attributes with the flat option set to Yes at the boundaries of the loft region that should have a flat constant scale/twist factor.
This option is similar to the Flat option for the variable Edge Fillet command and is used with the Scale or Twist/Variable/Add option above.
Select Yes or No to set the scale/twist factor as flat. If set to Yes, the attribute symbol is placed at the selected point on the drive curve.
Modify
Modify a scale/twist attribute currently attached to the drive curve. This option is used with the Scale or Twist/Variable option above.
Select the dimension (scale/twist attribute) to modify.
Enter a new value (scale/twist factor).
Repeat steps 1 and 2 until all scale/twist attributes are modified as desired and then middle-click to continue.
Delete
Select the scale/twist attribute to delete. This option is used with the Scale or Twist/Variable option above.
During the Drive Curve and Profile inputs 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.
