Meshes and Surfaces - Autodesk AutoCAD 2013 Practical 3D Drafting and Design - page 443

Polyface meshes
Polyface meshes were the first 3D objects in AutoCAD. These meshes are based
on 3D faces defined by three or four vertices. Only the 3DFACE command is import-
ant, as introduced and used in Chapter 5 , 3D Primitives and Conversions . Polyface
meshes still have one advantage related to other surfaces and meshes: vertices can
be stretched easily.
Creating polyface meshes
Besides the important 3DFACE command, some others are available, but mainly used
for programming. None of these commands have icons.
If the MESHTYPE variable has value 0 ; the RULESURF , TABSURF , REVSURF , and
EDGESURF commands, which were presented before, create polyface meshes. The
result of exploding polyface meshes are 3D faces.
These commands have no Undo option. An error in specifying a vertex requires com-
mand cancelation or posterior modification.
The 3DFACE command
The 3DFACE command (alias 3F ) creates faces defined by three or four vertices. A
single command application allows creating several contiguous faces:
Command: 3DFACE
The command prompts for a sequence of points that are defined in clockwise or coun-
terclockwise directions. The Invisible option allows turning invisible points to the next
edge:
Specify first point or [Invisible]: Point1
Specify second point or [Invisible]: Point2
Specify third point or [Invisible] <exit>: Point3
Specify fourth point or [Invisible] <create
three-sided face>: Point4