Constraints > Collinear

Command call:

This constraint can be applied only to straight line segments, including those obtained, when constructing polygons and chamfers.

The constraint moves the segments, so that they are always on the same line.

 

If positions of both segments are not fixated by other constrains, then, upon applying a collinear constraint, the segment selected second will be moved, while the first segment keeps its position. If position of the second segment is fixated, then the first one will be moved. If positions of both segments are fixated, then the new constraint will throw an error.

 

In this context, a segment is considered fixated, if at least one of its points are fixated and there are no fixated points of another segment. Length of a segment is kept upon moving, except cases where each of two segments have a single fixated point. In the latter case, non-fixated points of both segments will be moved, which leads to changes of their length.

 

The constraint allows to select multiple second objects.

 

If collinear segments are placed at some distance from each other, then a thin dashed line connecting them will be displayed, upon selecting their collinear constraint or moving cursor over it.

 

Icons of constraint are displayed near midpoints of each constrained line. If there are multiple constraints of this type applied to the same line, then all of these constraints are represented by a single icon. When pointing the cursor to an icon representing multiple constraints, you can select a particular constraint using selection hints.

By default, a numerical index is displayed near constraint's icon in drawing. It is the number of the line the constraint put its objects on. Thus you can easily distinguish groups of objects laying on the same line, when there are multiple collinear constraints putting objects on different lines. Indexes display may be disabled in system options.

Examples

Collinearity of Two Segments

Sequentially select the segments with the help of , end input using or <Ctrl>+<Enter>.  The segment selected second (in this case, the one that does not belong to the polygon) is moved to stay on the same line with the first segment. Depending on the initial position of the segments, upon applying the constraint, they might be placed at some distance from each other, or overlap each other fully or partially.

When creating a constraint, an icon appears on the drawing, similar to the one that invokes the command.

When editing one of the segments, the second one will change its position to stay in line with the first, which may result in changing the distance between segments.

Collinearity of Several Segments

First, select the segment, which other segments should be collinear with, then sequentially select other segments in any order with the help of and end input using or <Ctrl>+<Enter>. The parameters window will indicate, that several second objects have been selected (in this case, four). All second segments have moved to be on the same line with the first one. Four constraints were automatically created for the five segments: one constraint for each pair of object 2 with object 1. As in the case of two segments, changing position of any of the five segments will lead to a change in the position of the others.