HorVer Constraint¶

In one sentence: Force a line to be exactly horizontal, exactly vertical, or automatically whichever of the two it is closest to — removing the line's rotational degree of freedom.

Overview¶

Workbench: Sketcher · Menu: Sketch → Sketcher constraints → Horizontal/Vertical Constraint
Toolbar: Sketcher Constraints · Shortcut: H (Horizontal) · V (Vertical) · A (HorVer auto)

Tool	Shortcut	Description
Horizontal	`H`	Force selected line(s) to be parallel to the sketch X-axis
Vertical	`V`	Force selected line(s) to be parallel to the sketch Y-axis
HorVer (auto)	`A`	Apply Horizontal or Vertical based on which is closer to the current orientation

All three remove 1 degree of freedom (the rotational orientation of the line). For a pair of points instead of a line, the constraint forces the two points to share the same Y coordinate (Horizontal) or same X coordinate (Vertical).

Intuition¶

A newly drawn line can rotate freely around its midpoint. Horizontal snaps it flat — like a spirit level indicating the line is perfectly level. Vertical snaps it upright, like a plumb line. HorVer is a shortcut that reads the current angle and applies the nearest option, saving you a decision.

When to use it¶

Any line that should be a true horizontal edge (shelf, table top, floor line).
Any line that should be a true vertical edge (wall, column, post).
After drawing a line at approximately the right angle, use A to snap it to the exact axis without having to decide H or V yourself.
To force the flat side of a hexagon to be horizontal (apply Horizontal to one of the flat sides).

When NOT to use it¶

You want the line at a specific non-axis angle — use Angle instead.
You want two lines to be parallel to each other (not necessarily to an axis) — use Parallel.

Step-by-step walkthrough¶

Select one or more lines (or pairs of points for point-to-point mode).
Press H, V, or A depending on the desired axis.
The line(s) snap to the chosen orientation immediately. The constraint icon appears next to each affected line.

Tip

You can apply Horizontal or Vertical while drawing a Polyline by pressing H or V at a corner — this locks the segment currently being drawn to the axis before you click the next point.

Parameters¶

No numeric parameters. The constraint removes exactly 1 DoF per line.

Constraint	DoF removed	Requirement
Horizontal (on a line)	1	Line becomes parallel to X-axis
Vertical (on a line)	1	Line becomes parallel to Y-axis
Horizontal (on two points)	1	Points share the same Y coordinate
Vertical (on two points)	1	Points share the same X coordinate

Common mistakes and pitfalls¶

Constraint makes the sketch over-constrained

Cause: The line was already forced to be horizontal/vertical by a combination of existing constraints (e.g. both endpoints had Lock Position constraints that implied the same Y coordinate).
Fix: Remove one of the redundant Lock Position constraints and rely on the Horizontal/Vertical constraint to enforce the axis alignment.

HorVer applied Horizontal when you wanted Vertical

Cause: The line was drawn closer to horizontal than to vertical.
Fix: Press Ctrl+Z to undo, rotate the line closer to vertical (drag an endpoint), then press A again — or use V directly.

Python API¶

Minimal example¶

import FreeCAD as App
import Sketcher
import Part

doc = App.activeDocument()
sketch = doc.getObject("Sketch")

# Add a line and constrain it horizontal
idx = sketch.addGeometry(
    Part.LineSegment(App.Vector(0, 5, 0), App.Vector(20, 5.3, 0)), False)

sketch.addConstraint(Sketcher.Constraint("Horizontal", idx))
doc.recompute()
# The line snaps to Y=5 (the start Y), removing the slight tilt.

Method signatures¶

# Horizontal on a line
sketch.addConstraint(Sketcher.Constraint("Horizontal", geoId))

# Vertical on a line
sketch.addConstraint(Sketcher.Constraint("Vertical", geoId))

# Horizontal between two points (same Y)
sketch.addConstraint(Sketcher.Constraint("Horizontal", geo1, vertex1, geo2, vertex2))

# Vertical between two points (same X)
sketch.addConstraint(Sketcher.Constraint("Vertical", geo1, vertex1, geo2, vertex2))