Graphics Programs Reference
In-Depth Information
TABLE 20.1:
Effects of objects on the orientation of a UCS
(CONTINUED)
OBJECT TYPE
UCS ORIENTATION
Line
The endpoint nearest the pick point establishes the origin of the UCS, and the
XZ plane of the UCS contains the line.
Point
The point location establishes the UCS origin. The UCS orientation is arbitrary.
2D polyline
The starting point of the polyline establishes the UCS origin. The X axis is deter-
mined by the direction from the fi rst point to the next vertex.
3D polyline
Returns the message This object does not define a coordinate
system.
Spline
The UCS is created with its XY plane parallel to the XY plane of the UCS that was
current when the spline was created.
Solid
The fi rst point of the solid establishes the origin of the UCS. The second point of
the solid establishes the X axis.
Tr a c e
The direction of the trace establishes the X axis of the UCS, and the beginning
point sets the origin.
3D Face
The fi rst point of the 3D Face establishes the origin. The fi rst and second points
establish the X axis. The plane defi ned by the 3D Face determines the orienta-
tion of the UCS.
Shapes, text, blocks,
attributes, and attribute
d e i n i t i o n s
The insertion point establishes the origin of the UCS. The object's rotation
angle establishes the X axis.
UCS Based on Offset Orientation
At times, you may want to work in a UCS that has the same orientation as the current UCS but is
offset. For example, you might be drawing a building that has several parallel walls offset with a
sawtooth effect (Figure 20.12).
You can easily hop from one UCS to a new, parallel UCS by using the UCS Origin option.
Click Defi ne UCS Origin from the Coordinates tool group. You can also choose Tools
New UCS
Origin on the menu bar or type
UCS
↵
O
↵. At the Specify new origin point
<0,0,0>: prompt, pick the new origin for your UCS.
Another UCS option, called Move, will move an existing, named UCS to a new location and
keep its original orientation. You won't fi nd the UCS Move option on any tool group or menu
bar, but you can use it by entering
UCS
↵
M
↵ at the Command prompt.
The steps in the following section are for information only and aren't part of the tutorial. You
can try this at another time when you aren't working through an exercise.
