Line on Database segments are constrained to lie on an underlying database curve, surface, or quilt and are piece-wise linear. This segment type
should be used whenever you want to create a connector along a constant parameter line on a database entity such as a surface boundary.
Tip: Projecting a connector onto a database surface creates a new control point for each grid point projected. Since having many control
points can make editing a connector time-consuming, consider creating the database-constrained connector by hand, instead of projection, by using
the Line on Database or Curve on Database commands.
The On Database frame contains the Begin, Cancel, and Default commands which allow the specification of the underlying
database entities. Begin allows you to select the target projection entities from all those currently visible. After this button is pressed, you can
select database entities from either the List panel or the Display window. Note
that the current set of target entities (if any) is already selected when the button is first pressed. The button remains depressed with the text End
now displayed. Pressing End, stops the selection of projection database entities. The selection operation can be canceled at any time by pressing
the Cancel button.
When checked on, the Force Drawing in Parametric Space option will allow you to draw lines on surfaces containing multiple parametric (u,v)
spaces. Examples of such surfaces are quilts assembled from multiple component quilts and shells. When this option is unchecked (default state), the line
being drawn will halt at the edge of each parametric space.
The selection of database curves can be enabled or disabled using the Allow Drawing on Database Curves option.
The Project Shape To DB command becomes available once a second control point is chosen on a database surface. Use this command to project the shape
of a line onto a database by adding control points. This command is generally used when a line passes over a hole on a quilt or trimmed surface. Control
points will then be added so that the line goes around the hole. Note that since the point insertion is conservative, the command may need to be applied
multiple times to add more control points.
Use Project Shape To DB in the On Database Options frame to modify your line/curve such that it conforms more to the underlying database.
Tip: The Line on Database and Curve on Database commands are particularly useful for creating connectors which do not
lie on the boundaries of a database entity. Boundary connectors can be easily created using the Connectors on Database Entities command (refer to
the On Database Entities section for further details).