Using Dimensional Constraints – Bricsys Support and Help Center

Commands: DIMCONSTRAINT, DCALIGNED, DCANGULAR, DCCONVERT, DCDIAMETER, DCDISPLAY, DCHORIZONTAL, DCLINEAR, DCRADIUS, DCVERTICAL, DELCONSTRAINT

Overview: The dimensions of the geometry can be controlled by dimensional constraints:

Horizontal distance between points (1).
Vertical distance between points (2).
Distance between points or the length of lines and polyline segments (3).
Radius of arcs, circles and arc polyline segments (4).
Diameter of arcs, circles and arc polyline segments (5).
Angle between entities or between points and entities (6).

Note: Dimensional constraints are created using thencurrent dimension style.

To edit dimensional constraints

Dimensional constraints can be edited:

using the DDEDIT command
in the Properties bar
in the Mechanical Browser

To edit dimensional constraints in the Properties bar.

Select the dimensional constraint.
The properties of the entity display in the Properties bar.

Type a new value or expression in the Expression field, then press Enter.
The readout of the Value field changes accordingly.

(option) Edit the Name field.

(option) Edit the Description field.

(option) Edit the Text rotation field.

Press the Esc key to unselect.

Note: Select multiple dimensional constraints simultaneously to set their value equally.

To edit dimensional constraints in the Mechanical Browser:

If not already open, open the Mechanical Browser.

Select a parameter.
The properties the selected parameter display in bottom part of the Mechanical Browser.

(option) Select the Name field, then type a new name.

(option) Select the Expression field, then type a new value or expression.

(option) Select the Description field, then type a new description.

(option) Set the Exposed field, which specifies whether the parameter is exposed when the drawing is inserted in another drawing using BmInsert.
The options are:
- Auto : the parameter is exposed only if it does not depend on other parameters.
- ON = the parameter is always exposed.
- OFF = the parameter is never exposed.

(option) Set the Units property: Undefined, 1-dimensional (linear), 2-dimensional (planar) or 3-dimensiona (volume)l.
Select the field, then click the down-arrow button and choose an option.

To edit a single dimensional constraint:

Double click the dimensional constraint.
You are prompted: _ddedit
The Edit Text dialog box displays.

Type a new value in the Text field, then press Enter or click the OK button.
The new value is applied and the geometry is rebuild accordingly.

To edit multiple dimensional constraints:

Type ddedit or ed in the command bar, then press Enter.
You are prompted: Select entity to modify:

Click the a dimensional constraint.
The Edit Text dialog box displays.

Type a new value in the Text field, then press Enter or click the OK button.

(option) Repeat steps 2 and 3 to edit more dimensional constraints.

Press Enter or right click to stop editing dimensional constraints.
All edited dimensional constraints are updated simultaneously.
The geometry is rebuild accordingly.

To set the visibility of dimensional constraints

Tools to control the display of dimensional constraints sit on the Dimensional Constraint toolbar.
Dimensional constraints are hidden when a drawing is closed and reopened.

To set the display of dimensional constraints of a selection of entities

Do one of the following:
- Click the Show/Hide Dimensional Constraint tool button () on the 2D Constraints or Dimensional Constraint toolbar.
- Choose Show/Hide Dimensional Constraint in the Parametric menu.
- Type dcdisplay in the command bar.
You are prompted: Select Entities.

Select the entities, then right click or press Enter.
BricsCAD reports the number of selected entities.
You are prompted: Enter an option [Show/Hide] <Show>:

A prompt menu displays:

Do one of the following:
- Press Enter to display the dimensional constraints of the selected entities.
- Choose Hide or Show in the context menu.
- Type H or S in the command bar, then press Enter.

To set the visibility of the dimensional constraints of all entities

Do one of the following:

Click the Show All tool button () on the Dimensional Constraint toolbar to display the dimensional constraints of all entities.
Click the Hide All tool button () on the Dimensional Constraint toolbar to hide the dimensional constraints of all entities.

NOTES

The DYNCONSTRAINTMODE system variable controls the visibility of hidden dimensional constraints when selecting entities:

ON: Display dimensional constraints when entities are selected.
OFF: Dimensional constraints remain hidden when entities are selected.

The DYNCONSTRAINTMODE system variable controls the visibility of hidden dimensional constraints when the constrained entity is selected. When hovering over an entity with a dimensional constraint, the blue constraint glyph () displays if the SELECTIONPREVIEW system variable is set to 1 or 3

Using expressions to define dimensional constraints

Each dimensional constraint is named automatically upon its creation.

The naming is as follows:

distance: d1, d2, d3, ...

radius: rad1, rad2, rad3, ...

diameter: dia1, dia2, dia3, ..

angular: ang1, ang2, ang3, ..

The name of a constraint can be used as a parameter in a mathematical expression to define another dimensional constraint.

The dimensions of the bracket below are controlled through the rad1 radius, d1 distance and ang1 angular dimensional constraints.

The radius of the hole (rad2 ) and the length of the second leg (d2 ) are defined by expressions.

Geometrical constraints force the width of the second leg and the hole in it to be equal to the first leg.

Creating a new parameter

Select either the part name or Parameters in the Mechanical Browser, then right click.
A context menu displays.

Select Add new parameter in the context menu.
A new parameter is created.

Edit the properties of the new parameter.

NOTES

The constants Pi=3.14... and e=2.72... can be used in expressions. The constants names are not allowed to be used as parameter name and name of 3D constraint.
The CLEANUNUSEDVARIABLES command purges parameters that are not used in constraint expressions or linked to dimensions.

Tutorial: 2D Dimensional Constraints

Click here to watch

Using operators in expressions

The following operators can be used in expressions:

Operator	Description
+	Addition
-	Subtraction or Negative
*	Multiplication
/	Division
^	Exponentiation
%	Modulo or Remainder operator The expression "5 % 2" would evaluate to 1, because 5 divided by 2 leaves a quotient of 2 and a remainder of 1 .

Expressions are evaluated according to the standard mathematical rules of precedence:

Expressions within brackets; innermost sets first.
Standard operations order:
1. exponent
2. multiplication and division
3. addition and subtraction
Operators of equal precedence from left to right.

Using functions in expressions

The following functions can be used in expressions:

Function	Syntax
Cosine	cos(expression)
Sine	sin(expression)
Tangent	tan(expression)
Arc cosine	acos(expression)
Arc sine	asin(expression)
Arc tangent	atan(expression)
Hyperbolic cosine	cosh(expression)
Hyperbolic sine	sinh(expression)
Hyperbolic tangent	tanh(expression)
Arc hyperbolic cosine	acosh(expression)
Arc hyperbolic sine	asinh(expression)
Arc hyperbolic tangent	atanh(expression)
Square root	sqrt(expression)
Signum function (-1,0,1)	sign(expression)
Round to nearest integer	round(expression)
Truncate decimal	trunc(expression)
Round down	floor(expression)
Round up	ceil(expression)
Absolute value	abs(expression)
Largest element in array	max(expression1;expression2) 1
Smallest element in array	min(expression1;expression2) 1
Degrees to radians	d2r(expression)
Radians to degrees	r2d(expression)
Logarithm, base e	ln(expression)
Logarithm, base	10 log(expression)
Exponent, base e	exp(expression)
Exponent, base 10	exp10(expression)
Power function	pow(expression1;expression2) 1
Random decimal, 0-1	Random

(1) Use the list separator character as defined on your system: , (comma) or ; (semicolon).