Relationships and dimensions
Relationships tie sketch geometry together: this line stays horizontal, these two circles share a centre, this diameter is 5 mm. A solver keeps them true as you edit, so connected curves follow when a dimension changes.
Adding a relationship
- In the sketch bar, switch what clicking does to Relate.
- Click a point or a curve. ⇧-click to add another. The picked items are numbered in the order you chose them, which is the order the relationship uses.
- Choose a relationship from the buttons that appear.
Only relationships that make sense for what you picked are offered. One that fits the selection but that the solver cannot accept is shown greyed out, with the reason in its tooltip.
Relationships
| Relationship | Pick |
|---|---|
| Coincident | Two points |
| Point on curve | A point and a curve |
| Horizontal, Vertical | One line, or two points |
| Parallel, Perpendicular | Two lines |
| Tangent | A line and a circle or arc, or two circles or arcs |
| Midpoint | A point and a line |
| Concentric | Two circles, arcs or ellipses |
| Equal | Two lines, or two circles or arcs |
| Symmetric | Two points, then a line or a point to mirror about |
| Lock | One point, fixed in place |
Dimensions
| Dimension | Pick |
|---|---|
| Distance | Two points, or a point and a line |
| Horizontal distance, Vertical distance | Two points along one sketch axis, or one point to fix a coordinate |
| Length | One line |
| Radius, Diameter | A circle or arc |
| Angle | Between two lines |
A dimension is driving by default: changing its value changes the geometry. A reference dimension only reports the current size. Switch a dimension between the two from its row in the list.
The relationship list
Every relationship and dimension in the sketch is listed with its count. From each row you can:
- edit a driving dimension's value, by typing or by dragging;
- switch a dimension between driving and reference;
- for Tangent, choose which side the curves touch: Solver's choice, Outside or Inside;
- remove it.
Solver status
The bar shows how the sketch solves:
| Status | Meaning |
|---|---|
| Fully constrained | Nothing can move without breaking a relationship. |
| Underconstrained | Some geometry is still free to move. The number of free degrees is shown when known. |
| Overconstrained | A relationship repeats what others already fix. |
| Conflicting constraints | Relationships disagree. The change that caused it is not applied. |
| Could not solve | The solver did not find a solution. |
An underconstrained sketch is perfectly usable. Fully constraining a sketch is useful when you want later edits to behave predictably.
When a new relationship or value conflicts with existing ones, the sketch stays as it was and the relationships involved are marked in the list.