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434 Chapter 6: Transforms: Moving, Rotating, and Scaling Objec ts
Definitions
Cer t ain terms are used in the description of
transforms and the transform managers.
•Anaxis is a straight line along w hich an object
is moved or scaled, or about which an object is
rotated. When you work in 3D, you use three
axes, labeled X, Y, and Z, which are oriented 90
degrees from e ach other.
•Acoordinate system specifies the orientation of
the X, Y, a nd Z axes used by a transform.
For example, in the World coordinate system,
as seen from the Front view, the X axis runs
horizontally from left to right, the Y axis
runs from back to front, and the Z axis runs
vertically, from bottom to top.
On the other hand, each object carr ies its own
Local coordinate system. If the object has been
rotated, its Local coordinate system might be
different from the world coordinate system.
•Thetransform center, or pivot point, is the spot
about which a rotation takes place, or to and
from wh ich scaling occurs.
Using the tr ansform managers, you c an specify
any combination of axes, transform coordinate
systems, and transform centers.
Axis Tr ipod Icon
• An axi s tripod appears in the viewports when
you select one or more objects, to assist you
visually in your transforms. This tripod
consists of three lines, labeled X, Y, and Z, and
shows you three things:
• The orientation of the tripod reveals the
orientation of your coordinate system.
• The location of the junction of the three axis
lines shows you where your transform center is.
• The highlighted red axis lines show you the axis
or axes to which the transform is constrained.
For example, if only the X axis line is red, you
can move objects only along the X axis.
Note: The Transform gizmo supplants the axis
tripod for selections when a transform mode
is active. Besides providing all of the above
functions, it lets you specify the transform axis
or axes w ithout explicitly setting constraints;
see Using the Axis Constraints (page 1–437).
For more on the Transform gizmo, see Using
Transform Gizmos (page 1–426).
You can toggle t he display of the axis tripod in
all viewports by choosing Views menu > Show
Transform Gizmo, or by pressing the
X key.
Transfor m Manager Settings
The state of the three transform managers
(coordinate system, center , and axis constraints)
is stored with each type of transform. When you
switch from Mov e to Rotate to Scale, the transform
managers change to whatever combination they
were in when you last used that transform.
For example, if you click Rotate and set the
transform managers to Local, Selection Center,
and Y constraint, when you click Move, the
controls migh t shift to View, Pivot Point, and XY
constraint (whichever combination was set the
last time you used Move). When you go back
to Rotate, the controls revert to Local, Selection
Center, and Y constraint.
Tip: To avoid surprises, always click the transform
button first, and then set the transform managers.
If, instead, you first set the t ransform managers,
their settings are likely to change as soon as you
choose a new transform button. One way to
remember th is is always to set the transform a nd
managers by working from left to right on the
toolbar . Alternatively, you can turn on Customize
menu > Preferences > General tab > Reference
Coordinate System group > Constant, which keeps
the transform manager settings the same for all
transforms.