Variables are named values defined within a model, which
can be used to drive the model's geometry parametrically by associating
variables with dimensional constraints and element properties. When the value
of the variable changes, the value propagates to associated dimensions or
element properties, causing the geometry to update. Variables can be defined in
two ways:
- By attaching an Item Type
from within the Variables dialog. The properties of the Item Type become
available for use as variables. Item Types can be defined in the Item Types
dialog.
- By defining local
variables. Local variables are defined directly within the Variables dialog and
are specific to a single model, rather than being part of a general-purpose
Item Type. They are useful for defining temporary or construction variables
which drive geometry but are not necessarily considered integral properties of
the object being modeled.
Note: Property definition
names of an item type which you want to attach and the local variable names
shouldn't be same.
Variations are named sets of variable values. Each
Variation specifies a value for every Variable defined in the model. A
Variation can be applied to the model such that the "active" values of the
model's Variables are updated to reflect the values specified by the Variation.
A Variation can also be selected when placing a parametric cell, such that the
parametric cell's variables obtain their values from the values specified by
the Variation.
Variable Driven
Modeling and Constraints
When adding a constraint to a feature, you can bind the
dimensional value to a variable. When variables are used in this way, you can
"redesign" the element simply by changing the active values of the model's
variables. This results in the element being regenerated with the new values
applied to the constraints for the features. Similar effects can be achieved by
binding the value of an element property to a variable. To constrain to the
assigned variable value, you can select the available variables from the
drop-down menu that appears in the value field while applying the constraint.
Also, while
creating a parametric element or while applying a feature to an element, you
can use the variable driven tool settings to assign the value of that
particular dimensional setting from the available variables created in the
Variables dialog. If any variables of
a suitable type are defined for the model, you will be able to link these tool
settings with them by clicking
. When there are no variables of a
suitable type available to assign, clicking
will alert as follows:
Variables and
Parametric Cells
While placing a model as a parametric cell, you can
choose which variables and variations to use to define the cell.
To enable the placement of a
model as a parametric cell, you must set the model’s
Can be placed as Cell property to
True and its
Cell Type to
Parametric, in the model's
Properties dialog.
Note: A model which has
variables or variations but does not meet these requirements cannot be placed
as a parametric cell. A model which meets these requirements, can be placed as
a parametric cell regardless of whether or not it defines variables or
variations. But useful parametric cells usually define either or both.
The variables of a
placed parametric cell can be fixed (not editable) or free (editable) depending
on the
Scope setting set in the
Variables dialog. Also, the
visibility of the variables of a model placed as a cell, can be controlled with
the
Display setting in the
Variables dialog. Typically,
intermediate variables which are used to generate geometry but are not
considered useful outward properties of the object being modeled should be set
as
Hidden.
Set Scope to
Instance, if you want the variable editable after placing the cell | Set Scope
to Definition if you want the variable to be fixed.
Remapping
Variables and Variations -
If you try to delete a
variable that has been referenced in an element,
Confirm Delete dialog opens. You
can choose to remap the reference to another available variable, as below:
If
(None) is selected (default), you will lose
all the references to that variable.
Typically, you would
want to update a cell definition when the cell model changes in one or more of
the following ways:
- Added/removed variables
- Added/removed variations
- Changed the geometry
within the model
Let us take a scenario where
you had a Door model, placed it as a cell, then you (or the administrator in
your organization responsible for maintaining cell libraries you use) edited
the original model to include a knob and maybe added a variable which controls
the knob offset. In this situation, you can update your cell definition (and
cell elements) to reflect these changes by using
Update Parametric Cell dialog. This dialog will help you
remap the variables and variations of the outdated wooden plank model to that
of the updated door model as below:
