Graphics Programs Reference
In-Depth Information
Thickness is one way of adding height to an object, but
extruding
an object is
usually a better approach. You can extrude open or closed 2D objects to create a 3D ob-
ject. Extruding a closed 2D object, such as a polyline, spline, ellipse, circle, or region,
creates a 3D solid; extruding an open 2D object, such as a polyline, spline, line, or arc,
creates a surface. Figure 22-8 shows results of extruding open and closed objects.
To extrude an open or closed 2D object, click Extrude on the Solid panel of the Solid tab,
or click the Extrude split button on the Home tab's Modeling panel (if you see a button
labeled Loft, Revolve, or Sweep, click the lower part of the split button and choose Ex-
trude from the drop-down menu). Use the MOde option to control whether you create a
surface or 3D solid from a closed object, select the objects you want to extrude, and
specify an extrusion height or distance to create the 3D solid.
The DELOBJ system variable controls whether the 2D objects you use to cre-
ate 3D solids is retained or erased. Most of the time, you probably want to keep
the source geometry, but the default DELOBJ setting erases it. If you want to keep
the original 2D geometry, type
DELOBJ
and set its value to 0. (See Chapter 26 for
more about system variables.) DELOBJ also controls whether or not the source
objects for associative arrays (introduced in Chapter 18) are retained or deleted.
Figure 22-8:
2D to 3D by extrusion is easy as 1, 2, 3.
Press and pull closed boundaries
