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The Current Transform Button: Current Transform Panel
The Current Transform button in the Edit Menu brings up
the Current Transform panel, which allows the current transform
to be set. The current transform is applied to newly-placed subcells,
and to objects which are moved or copied.
The transform that is applied to an instance of a cell is saved in an
irreducible form in the database representation of the instance. The
irreducible form is an optional reflect-y (
y
- y),
followed by an optional rotation, followed by the translation. This
maps directly to the format used in GDSII files. However, the
``current transform'' applies rotation before the reflection, so
that on screen, a reflect-x, for example, will flip the object's x
coordinates independent of any rotation angle, which is what users
tend to expect. The transform string printed on unexpanded instances
and on the status line reflects this, i.e., forms like ``R45M''
imply a 45 degree rotation followed by a reflect-y (``M'' always
denotes reflect-y, reflect-x is equivalent to some other rotation and
reflect-y combination). However, the transformation shown in an Info window will be reflect-y followed by a 315 degree rotation (in
this example), since the internal representation performs the
reflection before the rotation.
If the current transform is set to something other than the default
identity transform, the transform code is printed on the status line.
The following buttons and input fields are available in the
Current Transform panel.
- Reflect X
Add a reflection of the x-axis to the current transform. The
X-reflection is toggled by the Ctrl-Down Arrow key sequence,
whether or not the Current Transform panel is visible.
- Reflect Y
Add a reflection of the y-axis to the current transform. The
Y-reflection is toggled by the Ctrl-Up Arrow key sequence,
whether or not the Current Transform panel is visible.
- Rotation Angle
This choice menu allows setting the rotation component of the current
transform. The menu allows a choice of rotations in increments of 90
degrees in electrical mode or 45 degrees in physical mode.
Pressing and holding the Ctrl key and then pressing the left or
right arrow keys cycles through the transformation angles, whether or
not the Current Transform panel is visible. The right arrow
increases the angle, the left arrow decreases the angle.
- Magnification
This entry field allows setting of the magnification component of the
current transform. Any number from 0.001 through 1000.0 can be
entered.
- Identity Transform
This button will save the current parameters to internal storage, and
reset these values to the default state (no transformation). The
saved state can be restored with the Last Transform button.
This fuction is also available from the IT button in the upper-left
corner of the main drawing window, next to the WR button.
- Last Transform
This button will restore the state of the current transform last saved
with the Identity Transform button, or one of the recall
buttons. If no state has been saved, the identity transform (the
default) is set. Note that there is separate storage for the current
transform in electrical and physical modes.
This fuction is also available from the LT button in the upper-left
corner of the main drawing window, next to the IT button.
- Store and Recall
There are five internal registers for storage of transformation
parameters. Separate registers are used in electrical and physical
modes. Pressing these buttons will either save the current parameters
to a register, or set the parameters from a register. After a recall,
the original parameters can be restored with the Last Transform
button.
Next: The Place Button: Cell
Up: The Edit Menu: Edit
Previous: The Merge, Clip Boxes
Contents
Index
Stephen R. Whiteley
2012-04-01