Constraints

Experimental status: constraints are an experimental function group. On the first call of a constraint tool the program shows the notice “⚠ Constraints are still experimental” and marks it in the floating tooltip.

Purpose#

A constraint fixes a geometric relationship — a line stays horizontal, two lines stay parallel, two circles concentric. When set, the program aligns the second element to the first at once; afterwards a solver maintains the relationship on every change of the geometry. Every constraint appears as a small symbol at all elements involved.

Step by step: Set and release constraints. Field by field: “Constraints” section.

Access#

• Ribbon: group “Constraints” — the split button Constraints opens the list of all eleven constraints with its triangle (1–11); the button itself starts “Horizontal”.
• Classic toolbar: group “Constraints” as a drop-down button. If the window is not wide enough, the group sits in the menu “☰” (“Menu / more tools”) at the right of the toolbar (1) and unfolds there (2).
• Tool window, section “Constraints”: “Fix horizontal”, “Fix vertical”, “Fix position” (1–3).
• Command search : “constraint” — entries “Constraint: Horizontal” etc.

Procedure#

With the tool the snap mode switches to Free. The floating tooltip names what to click at each step; the first clicked element is always the reference and stays unchanged, the second is adapted. After the last click the status bar reports “Constraint: … applied”, the tool stays active for the next constraint. If the selection does not fit, the reason appears with “⚠” in the status bar and the clicks are discarded (Messages).

The eleven constraints#

Horizontal#

One click on a line. The line is rotated horizontal — about its midpoint, so both endpoints share the change; the direction is kept (no flipping). Not combinable with “Vertical” (“The line is already vertical — it cannot also be horizontal”).

Vertical#

One click on a line: it becomes vertical, rotated about the midpoint as well.

Perpendicular#

1st click reference line, 2nd click second line → it is rotated perpendicular to the reference, on the side where it already lies (no flipping). Not combinable with “Collinear” on the same pair.

Parallel#

1st click reference line, 2nd click second line → it is aligned parallel. Then a browser window asks “Abstand zwischen parallelen Linien:” (German in every language) with the current distance as proposal; a new value shifts the second line perpendicularly to that distance, “Cancel” leaves it.

Equal#

1st click reference, 2nd click target → two lines get the same length (the target is adjusted from its start point along its direction), two circles or two arcs the same radius.

Coincident#

1st click on an element near the endpoint that should move; 2nd click on the target: on an endpoint → point-to-point (“Coincident: points joined”), anywhere on a line or arc → the point lies on the element and slides along it (“Coincident: the point lies on the element”).

Concentric#

1st click reference circle or arc, 2nd click second circle or arc → it takes the centre of the reference. Needs two circles or arcs (“Concentric needs two circles or arcs”).

Tangent#

1st click circle or arc (its centre stays), 2nd click line or circle → the line is shifted perpendicular to itself to the distance “radius”; a second circle is shifted so the circles touch — inside or outside, whichever is closer to the current position. Allowed: circle/arc + line or two circles (“Tangent needs a circle/arc + line, or two circles”).

Collinear#

1st click reference line, 2nd click second line → its endpoints are projected onto the reference's straight line; both then lie on the same straight line.

Fixed#

One click on an element freezes its complete geometry: it can neither be moved nor resized — the solver restores the stored state on every change. In the tool window also as “Fix position”.

Point on intersection#

Three clicks: 1st a point element (is positioned), 2nd element A, 3rd element B → the point moves to the intersection of A and B; if the elements do not intersect directly, to the extended intersection. A and B must be a line, circle, arc or polyline; parallel lines have no intersection (“The elements do not intersect even when extended (parallel lines?)”).

Symbols, visibility and panel#

Every constraint is drawn as a symbol at every element involved; several symbols at one element stack. The symbols are construction aids: they appear neither in the viewports of a sheet nor in print. The system layer “Constraints” hides them — the constraints stay in force.

The “Constraints” section in the panel on the right lists the constraints of the one selected element as tags; ✕ on a tag deletes the constraint.

Deleting a constraint#

• Right-click on a symbol in the drawing opens a mini menu with the name of the constraint and “🗑 Delete constraint” (status bar “Constraint deleted”).
• “Constraints” section: ✕ on the tag of the selected element.
• Deleting an element involved removes the constraint too; “Check & clean drawing” in the file menu finds constraints without an element.

The notice “experimental”#

With the first constraint tool a pill “⚠ Constraints are still experimental” appears at the bottom centre with the button “don't show again ✕”; the click is remembered in the browser (“Notice hidden — constraints remain experimental.”). The mark “⚠ experimental function group” in the floating tooltip remains.

Rules#

• Every constraint is one undo step (Ctrl + Z), including the distance after “Parallel”.
• The same constraint can be set only once per element or pair (“This constraint already exists on the element”, “The same constraint already exists on this pair”); elements A and B must be different.
• Contradicting combinations are rejected (horizontal/vertical, perpendicular/collinear, two lines already parallel or perpendicular).
• Constraints are saved with the drawing, copied with blocks and via the clipboard, and taken along when copying layer contents or a group.
• The solver works iteratively (up to 15 passes per change); with many chained constraints a geometry may lag.

Related commands#

• Snap mode — construction without a permanent constraint
• Weld — join endpoints permanently
• “Constraints” section