Introduction

Constraints specify geometric and dimensional properties of entities.

When working with Constraints, you can control the visibility of

• Constraint Icons
• Dynamic Dimensions

Additional tools let you

• Delete Constraints
• Manage Dimensional Constraints Parameters
• Modify Dimensional Constraints Parameters
• Set Constraint Options
• Set the Dimensional Constraint Dimension Text Format

Geometric Constraints

This topic discusses:

• Understanding Gometric Constraints
• Controlling the Visibility of Geometric Constraint Icons

Understanding Geometric Constraints

Geometric Constraints define relationships that force dependencies and limitations between entities.

There are two types of Geometric Constraints: those that act on a single geometric entity and those that define a relationship between two geometric entities.  For example, the Fix, Horizontal, and Vertical Geometric Constraints act on a single entity, whereas Perpendicular, Parallel, Tangent, and others control two entities.

You can apply Geometric Constraints to 2D entities only.

Constraint Points

When you use a Geometric Constraint command and move the cursor over an entity, selectable constraint points are indicated with an icon .

This table lists the entity types to which you can apply Geometric Constraints. Also, it outlines valid constraint points per entity type:

This table lists the entity types that can have Geometric Constraints.

Entity Type	Constraint Points
Line	Endpoints, Midpoint
Linear PolyLine segment	Endpoints, Midpoint
Circle	Center
Arc	Endpoints, Midpoint
PolyLine Arc	Endpoints, Midpoint
Ellipse	Center
Elliptical Arc	Endpoints, Midpoint
Spline	Endpoints
SimpleNote	Insertion point, Alignment point
Note	Insertion point
Block	Insertion point
AttributeDefinition	Insertion point

 

Constraint Bars

Constraint bars group together the Geometric Constraints icons associated with an entity.

Example:

The constraints bar above shows that a horizontal, parallel constraint, collinear, and symmetric constraint are defined for a linear entity.

You can show or hide individual constraint bars, or show or hide them all. Also, you can relocate constraint bars to their default position. See: Controlling the Visibility of Geometric Constraint Icons.

Controlling the Visibility of Geometric Constraint Icons

Use the ConstraintIcon command to show or hide Geometric Constraint icons and bars. You can also reset the constraint icons to their default position.

Constraint bars assemble icons of Geometric Constraints associated with an entity.

To control the visibility of individual Geometric Constraint icons:

1. Click Constraints > Constraint Icons > Specify Entities (or type ConstraintIcon).
2. Specify a Geometric Constraint entity.
3. If necessary, repeat step 2 for more entities.
4. Specify an option:
   • Show: Shows the constraint icons of the specified entities.
   • Hide: Hides the constraint icons of the specified entities.
   • Reset: Relocates the constraint icons of the specified entities to their default position.

To show all Geometric Constraint icons:

• Click Constraints > Constraint Icons > Show All (or type ConstraintIcon, then specify ShowAll).

To hide all Geometric Constraint icons:

• Click Constraints > Constraint Icons > Hide All (or type ConstraintIcon, then specify HideAll).

To reset all Geometric Constraint icons:

• Click Constraints > Constraint Icons > Reset All (or type ConstraintIcon, then specify ResetAll).

  Note: When you reopen a drawing that contains Geometric Constraints, all constraint icons are hidden. Use the ShowAll option of the ConstraintIcon command to redisplay them.

Access

Command: ConstraintIcon

Menu: Constraints > Constraint Icons

Dimensional Constraints

This topic discusses:

• Understanding Dimensional Constraints Types
• Controlling the Visibility of Dimensional Constraints
• Modifying Dimensional Constraint Parameters
• Hiding the Parameters Palette

Understanding Dimensional Constraint Types

You can apply two types of Dimensional Constraints:

There are two types of Dimensional Constraints:

• Dynamic: This type is shown only in the graphics area and do not print. It requires no user-defined DimensionStyle. The dimension text is positioned automatically. Dynamic Dimensions maintain the same size when zooming in or out.
• Annotation: This type is printed and uses the current DimensionStyle.

Also, you can decide whether Dimensional Constraints are

• Constrained: Geometry is driven from the dimension.
• Derived: Dimension is derived from the geometry.

Dynamic and Annotational Dimensional Constraints

Dynamic and Annotational Dimensional Constraints differ in the following characteristics:

Characteristics	Dynamic Constraints	Annotational Constraints
Zoom	Maintain the same size when zooming in and out	Change size when zooming in and out
DimensionStyle	Use a fixed, predefined DimensionStyle	Use the current user-defined DimensionStyle
Entity Properties	Ignore Layer, LineStyle, and LineColor settings	Use the current Layer, LineStyle, and LineColor settings
Print Output	Are not shown on printouts	Display on printouts

Controlling the Visibility of Dimensional Constraints

Use the DcDisplay command to show or hide Dimensional Constraints.

To control the visibility of individual Dimensional Constraints:

1. Click Constraints > Dynamic Dimensions > Specify Entities (or type DcDisplay).
2. Specify a Dimensional Constraint.
3. If necessary, repeat step 2 for more entities.
4. Press Enter.
5. Specify Show or Hide to show or hide the specified dynamic dimensions.

To show all Dimensional Constraints:

• Click Constraints > Dynamic Dimensions > Show All (or type DcDisplay, then specify ShowAll).

To hide all Dimensional Constraints:

• Click Constraints > Dynamic Dimensions > Hide All (or type DcDisplay, then specify HideAll).

Access

Command: DcDisplay

Managing Dimensional Constraint Parameters

Modifying Dimensional Constraint Parameters

Use the Parameters command to display the Parameters Manager palette to view and modify Dimensional Constraints parameters.

Use the Parameters command to display the Parameters Manager palette to view Dimensional Constraints parameters.

You can define, modify, rename, and delete constraint expressions and variables.

The Parameters Manager lists:

• Names of the Dimensional Constraints,
• Expressions
• Expressions, in which you can use:
  • Values
  • User-defined variables, and variables that represent existing Dimensional Constraints
  • Mathematical operators, functions, and constants
• Values that result from the expression

The list is grouped into Dimensional Constraints defined in the graphics area, and User-defined variables.

For detailed information about using expressions and variables, see Defining Dimensional Constraints Parameters.

To display the Parameters Manager palette:

• Click Constraints > Parameters Manager (or type Parameters).

To change names of Dimensional Constraints or user variables:

1. In the Parameters Manager list, click a Dimensional Constraint or a user-defined variable.
2. Edit the name.
3. Press Enter or click elsewhere.

To filter the Parameters Manager list:

1. On the Parameters Manager palette, expand Filter.
2. Select an option to control the display of user-defined variables in the list:
   • All: Displays all user-defined variables.
   • Used in expressions: Displays only the user-defined variables used in expressions.
   • Unused in expressions: Displays only the user-defined variables not used in expressions. Right-click, then click Delete Parameter to remove unused variables from the list.

To sort the Parameters Manager list:

• In the Parameters Manager list, click a column name in the title bar (Name, Expression, or Value) to sort the list alphabetically according to the column title.
• Click the same column title again to restore the previous order.

Access

Command: Parameters

Menu: Constraints > Parameters Manager

Hiding the Parameters Palette

Use the HideParameters command to hide the Parameters Manager palette.

To hide the Parameters Manager palette:

• Click Constraints > Parameters Manager (or type HideParameters).

Access

Command: HideParameters

Setting Constraint Options

Use the ConstraintOptions command to set options for Geometric and Dimensional Constraints.

To define Geometric Constraint settings:

1. Click Constraints > Constraint Options (or type ConstraintOptions).
2. Expand Geometric.
3. Under Constraint icons settings, activate the Geometric Constraints to display in the graphics area.

   Click Clear all to cancel the selections or Select all to select all Geometric Constraints.

4. Specify whether to:
   • Show constraint icons only for entities in the current plane
   • Show constraint icons after applying constraints to specified entities
   • Show constraints icons when entities are specified
5. Under Constraint icons transparency, specify the transparency percentage for constraint icons in the graphics area.
6. Click OK.

To define Dimensional Constraint settings:

1. Click Constraints > Constraint Options (or type ConstraintOptions).
2. Expand Dimensional.
3. Under Dimensional constraint format:
   • In Dimension name format, select Name, Value, or Name and Expression.
   • Specify whether to Show lock icon for annotational constraints.
   • Note: The lock icon is not visible in print output.
4. Under Show options, specify whether to Show hidden dynamic constraints for selected entities.
5. Click OK.

Access

Command: ConstraintOptions

Menu: Constraints > Constraint Options

Setting the Dimensional Constraint Dimension Text Format

Use the SetConstraintNameFormat command to specify how to display the information in the dimensional constraints.

To set the dimensional constraint dimension text format:

1. Type SetConstraintNameFormat at the command prompt.
2. Specify an option:
   • Name. Displays only the name (for example, Length).
   • Value. Displays only the value (for example, 2.54).
   • Expression. Displays the name and the value, as an expression (for example Length = 2.54).

Access

Command: SetConstraintNameFormat

Related Topic

Working with Constraints