Constraints reference

Kerf stores sketch constraints in the IR and solves them before sending geometry to the kernel. If a constraint set cannot solve, the workspace blocks regeneration and surfaces the reason instead of producing stale geometry.

Geometric constraints

• Coincident: two points occupy the same location, often closing a loop.
• Parallel: two lines keep the same direction.
• Perpendicular: two lines meet at 90°.
• Tangent: a line or curve touches another curve without a corner.
• Equal: two compatible entities share length or radius.
• Horizontal / Vertical: a line or point pair aligns to the sketch axes.
• Midpoint: a point stays halfway along a line segment.
• Symmetric: two entities remain mirrored about a line or axis.
• Collinear: line segments stay on the same infinite line.
• Concentric: circles or arcs share a centre.

Dimensional constraints

• Distance: fixes linear separation or line length.
• Angle: fixes the angle between two lines.
• Radius: fixes a circle or arc radius.

Dimensions can be typed as numbers or formulas. Formula values are resolved from document variables, so changing a variable can update many dimensions and features in one regeneration.

Solving notes

Prefer the fewest constraints that capture intent. Over-constraining a sketch can make the solver fail; under-constraining leaves geometry free to move. Construction geometry is useful for centre lines, symmetry axes, and references that should not become part of the profile.