TBranch

The Surface->TBranch command in the Model module performs branched extrusions. TBranch accepts a hierarchy of curves and an extrusion cross-section. The ends of each curve are checked to see if they lie near any other curves. If so, a T- junction is formed in the extrusion, with smooth curves connecting the stalk to the cross-piece.

The Path->AnimatedTBranch command in the Motion module is the animated version of this effect.

Procedure

1. Create a cross-section curve and a hierarchy of curves.
   
   The cross-section must be centered in the xy plane, have an even number of control points, and be reasonably symmetrical, such as a circle. It is usually better not to have control points of the cross-section lie exactly on the x-axis. If they do, as in the case of an eight-point circle, simply rotate the cross-section in z.
   
   The hierarchy of curves must not have more than one branch between consecutive control points of a curve. In the case of linear curves (or curves with a step of 1), there should be at least two control points between any two branches. For linear curves, it is best to place the branch exactly on a control point, while for non-linear curves, place the branch between control points.
   
   NURBS curves may be used as the cross-section or contained in the branching hierarchy. The NURBS curves in the branching hierarchy, however, are subdivided differently from other types of curves (linear, Bezier, B-Spline, or Cardinal), and may not produce accurate results.
   
2. Choose the Surface->TBranch command in the Model module.
   
   The TBranch dialogue box is displayed.
   
3. Set the parameters as desired.
4. Select the hierarchy of curves and the cross-section.

Parameters

Joining Range

If the distance between a curve end and any other part of any other curve is less than the joining range, a T-junction is formed; otherwise, the extrusions are done separately.

Tension

Describes how tight the curved sides of the T-junction should be. A tension value of 0 allows a relaxed fit, while a value of 1 forces the junction to follow the exact pattern of the curves. Values between 0.4 to 0.6 generally produce smooth results.

Disc. Angle

Sets the discontinuity angle of the output polygon mesh. An angle of 0 is totally faceted, while 180 is totally smooth.

Add Tube Caps

If this option is selected, it adds curved caps to the ends of the extrusion on open curves that do not form T-junctions with other curves.

Cap Step

The latitudinal curve step of the cap.

Cap Height Factor

Height of end caps in SOFTIMAGE units. A value of 0 corresponds to traditional flat capping on extrusions, while a value of 1 produces a hemispherical cap.

Last updated 02-apr-1998