Dimensional constraints
maintain specified distances and angles between geometric objects
or points on objects.
For
example, you can specify that the length of a line should always
remain at 6.00 units, that the vertical distance between two points
be maintained at 1.00 unit, and that a circle should always remain
at 1.00 unit in diameter.
When you apply a dimensional
constraint to an object, a constraint variable is automatically
created for maintaining the constraint value. By default, these are
assigned names such as d1 or dia1, but you
can rename them in the Parameters Manager.
Dimensional constraints
can be created in one of the following forms:
- Dynamic constraints
- Annotational constraints
The forms have different
purposes. In addition, any dynamic or annotational constraint can
be converted to a reference parameter.
Dynamic Constraints
By default, dimensional constraints are dynamic.
They are ideal for normal parametric drawing and design tasks.
Dynamic constraints have
the following characteristics:
- Maintain the same size when zooming in
or out
- Can easily be turned on or off globally
in the drawing
- Display using a fixed, predefined dimension
style
- Position the textual information automatically,
and provide triangle grips with which you can change the value of
a dimensional constraint
- Do not display when the drawing is plotted
If you need to control
the dimension style of dynamic constraints, or if you need to plot
dimensional constraints, use the Properties palette to change dynamic
constraints to annotational constraints.
Annotational Constraints
Annotational
constraints are useful when you want dimensional constraints to
have the following characteristics:
- Change their size when zooming in or
out
- Display individually with layers
- Display using the current dimension
style
- Provide grip capabilities that are similar
to those on dimensions
- Display when the drawing is plotted
NoteTo display the text
used in annotational constraints in the same format as used in dimensions,
set the
CONSTRAINTNAMEFORMAT system variable
to 1.
After plotting, you can
use the Properties palette to convert annotational constraints back
to dynamic constraints.
Reference Parameters
A reference parameter is a driven dimensional
constraint, either dynamic or annotational. This means that it does
not control the associated geometry, but rather reports a measurement
similar to a dimension object.
You use reference parameters
as a convenient way to display measurements that you would otherwise
have to calculate. For example, the width in the illustration is
constrained by the diameter constraint, dia1, and the
linear constraint, d1. The reference parameter, d2,
displays the total width but does not constrain it. The textual
information in reference parameters is always displayed within parentheses.
You can set the Reference
property in the Properties palette to convert a dynamic or annotational
constraint to a reference parameter.
NoteYou cannot change
a reference parameter back to a dimensional constraint if doing
so would overconstrain the geometry.
To convert associative
dimensions to dimensional constraints
- Select the associative dimensions you
want to convert.
- Press Enter.
To change the dimension
name format
- Select an annotational constraint, right-click
in the drawing area, and click Dimension Name Format.
- Select Value, Name, or Name and Expression.
The Expression reflects
the selected dimension name format.
CommandsDCALIGNED
Constrains the distance
between two points on different objects.
DCANGULAR
Constrains the angle
between line or polyline segments, the angle swept out by an arc
or a polyline arc segment, or the angle between three points on objects.
DCCONVERT
Converts associative
dimensions to dimensional constraints.
DCDIAMETER
Constrains the diameter
of a circle or an arc.
DCDISPLAY
Displays or hides the
dynamic constraints associated with a selection set of objects.
DCFORM
Specifies whether the
dimensional constraint being created is dynamic or annotational.
DCHORIZONTAL
Constrains the X distance
between points on an object, or between two points on different
objects.
DCLINEAR
Creates a horizontal,
vertical, or rotated constraint based on the locations of the extension
line origins and the dimension line.
DCRADIUS
Constrains the radius
of a circle or an arc.
DCVERTICAL
Constrains the Y distance
between points on an object, or between two points on different
objects.
DELCONSTRAINT
Removes all geometric
and dimensional constraints from a selection set of objects.
DIMCONSTRAINT
Applies dimensional
constraints to selected objects or points on objects, or converts
associative dimensions to dimensional constraints.
LIST
Displays property data
for selected objects.
PARAMETERS
Controls the associative
parameters used in the drawing.
-PARAMETERS
Controls the associative
parameters used in the drawing.
PARAMETERSCLOSE
Closes the Parameters
Manager palette.
TEXTEDIT
Edits a dimensional
constraint, dimension, or text object.
System VariablesCONSTRAINTNAMEFORMAT
Controls the text format
for dimensional constraints.
CONSTRAINTRELAX
Indicates whether constraints
are enforced or relaxed when editing an object.
CONSTRAINTSOLVEMODE
Controls constraint
behavior when applying or editing constraints.
DIMCONSTRAINTICON
Displays the lock icon
next to the text for dimensional constraints.
DYNCONSTRAINTMODE
Displays hidden dimensional
constraints when constrained objects are selected.
PARAMETERCOPYMODE
Controls how constraints
and referenced user parameters are handled when constrained objects
are copied between drawings, Model space and layouts, and block
definitions.
PARAMETERSSTATUS
Indicates whether the
Parameters Manager is displayed or hidden.
