Sketcher Dialog
Introduction
While a sketch is being edited, or, in other words, while a sketch is in edit mode, the Sketcher Dialog is displayed on the Task tab of the Combo view.
To put a sketch in edit mode do one of the following:
- Double-click the sketch in the Tree view.
- Right-click the sketch in the Tree view and select Edit sketch from the context menu.
- Select the sketch and press the
Edit sketch button.
- Select the sketch and then select the
Edit sketch option from the menu.
The dialog consists of the following sections:
Solver messages
This section informs about the state of the sketch. A sketch can be under constrained, fully constrained or have redundant constrains.
If a sketch is under constrained the number of degrees of freedom (or Dofs) is indicated. Clicking this text will select the under constrained sketch elements.
If a sketch has redundant constraints the indices of the constraints are indicated. Clicking that text will select these constraints.
Available options:
Option | Description |
---|---|
This button opens a menu:
|
Advanced solver control
This section will only appear if you check the Show section 'Advanced solver control' option in the sketcher preferences.
Note that most of the options in this section are of no practical use. They can however help with testing and understanding the solvers.
Available options:
Option | Description |
---|---|
Default solver | The solver that is used for solving the geometry. LevenbergMarquardt and DogLeg are trust region optimization algorithms. The BFGS solver uses the Broyden–Fletcher–Goldfarb–Shanno algorithm. |
DogLeg Gauss step | This setting is only available for the solver DogLeg. It is the step type used in the DogLeg algorithm. |
Maximum iterations | If the solver needs more iterations to find a convergence to a solution, it will stop and output that it failed. |
Sketch size multiplier | If checked, the maximum iterations will be multiplied by the number of parameters. The idea is that bigger sketches would need more iterations to converge. |
Convergence | The threshold for the squared error. This error is used to determine whether a solution converges or not. |
Eps/Eps1/Tau | These settings are only available for the solver LevenbergMarquardt. You should only change something here if you fully understand how the LevenbergMarquardt solver works. |
Tolg/Tolx/Tolf | These settings are only available for the solver DogLeg. You should only change something here if you fully understand how the DogLeg solver works. |
QR Algorithm | During diagnosing the rank of the matrix is calculated which enables to further analyze the constraint system to determine if there are redundant/conflicting constraints. The rank revealing decomposition used in FreeCAD is QR. There are two algorithms: Eigen Dense QR is a dense matrix QR with full pivoting, which is the legacy proven algorithm that works very well but it is rather slow as the system grows. The Eigen Sparse QR algorithm is an optimization for sparse matrices (having lots of zeros), which is usually much faster, since FreeCAD's systems do have a lot of zeros. |
Pivot threshold | When doing a QR, values under the pivot threshold are treated as zero. |
Redundant Solver | The solver that is used during diagnosing to determine whether a group is redundant or conflicting. |
Red. Max Iterations | The same as Maximum iterations, but for the redundant solving. |
Red. Sketch size multiplier | The same as Sketch size multiplier, but for the redundant solving. |
Red. Convergence | The same as Convergence, but for the redundant solving. |
R.Eps/R.Eps1/R.Tau | The same as Eps/Eps1/Tau, but for the redundant solving. |
R.Tolg/R.Tolx/R.Tolf | The same as Tolg/Tolx/Tolf, but for the redundant solving. |
Console Debug mode | Setting to specify the verbosity of the console output. |
Solve | This button explicitly starts the solver. |
Restore Defaults | This button restores the default solver settings. |
Constraints
This section lists the constraints in the sketch. Unchecking a constraint in the list will hide it in the sketch. Constraints can be selected in the list as well as in the sketch.
Available options:
Option | Description |
---|---|
Filter |
If the Filter checkbox is checked the Filter dropdown list controls which constraints are listed:
|
This button toggles the visibility of the listed constraints in the sketch. | |
This button opens a menu:
| |
Context menu | Right-clicking constraints selected in the list opens a context menu. The menu has the following options:
|
Elements
This section lists the elements in the sketch. Unchecking an element in the list will hide it in the sketch. Elements can be selected in the list as well as in the sketch.
Available options:
Option | Description |
---|---|
Filter |
If the Filter checkbox is checked the Filter dropdown list controls which elements are listed:
|
This button opens a menu:
| |
Each element in the list has 1 to 4 buttons organized in 4 columns. These select a specific part of the element. Only applicable buttons are shown.
Clicking the text has the same effect as clicking the first available button of the element. | |
Context menu | Right-clicking elements selected in the list opens a context menu. The menu contains the Geometric constraint tools, the Dimensional constraint tools and the following additional options:
|
- General: Create sketch, Edit sketch, Map sketch to face, Reorient sketch, Validate sketch, Merge sketches, Mirror sketch, Leave sketch, View sketch, View section, Toggle grid, Toggle snap, Configure rendering order, Stop operation
- Sketcher geometries: Point, Line, Arc, Arc by 3 points, Circle, Circle by 3 points, Ellipse, Ellipse by 3 points, Arc of ellipse, Arc of hyperbola, Arc of parabola, B-spline by control points, Periodic B-spline by control points, B-spline by knots, Periodic B-spline by knots, Polyline, Rectangle, Centered rectangle, Rounded rectangle, Triangle, Square, Pentagon, Hexagon, Heptagon, Octagon, Regular polygon, Slot, Fillet, Corner-preserving fillet, Trim, Extend, Split, External geometry, Carbon copy, Toggle construction geometry
- Sketcher constraints:
- Geometric constraints: Coincident, Point on object, Vertical, Horizontal, Parallel, Perpendicular, Tangent, Equal, Symmetric, Block
- Dimensional constraints: Lock, Horizontal distance, Vertical distance, Distance, Radius or weight, Diameter, Auto radius/diameter, Angle, Refraction (Snell's law)
- Constraint tools: Toggle driving/reference constraint, Activate/deactivate constraint
- Sketcher tools: Select unconstrained DoF, Select associated constraints, Select associated geometry, Select redundant constraints, Select conflicting constraints, Show/hide internal geometry, Select origin, Select horizontal axis, Select vertical axis, Symmetry, Clone, Copy, Move, Rectangular array, Remove axes alignment, Delete all geometry, Delete all constraints
- Sketcher B-spline tools: Show/hide B-spline degree, Show/hide B-spline control polygon, Show/hide B-spline curvature comb, Show/hide B-spline knot multiplicity, Show/hide B-spline control point weight, Convert geometry to B-spline, Increase B-spline degree, Decrease B-spline degree, Increase knot multiplicity, Decrease knot multiplicity, Insert knot, Join curves
- Sketcher virtual space: Switch virtual space
- Additional: Sketcher Dialog, Preferences, Sketcher scripting

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