Sketcher Dialog
Introduction
If you are in a sketch, the sketcher dialog is shown in the Combo view panel in the tab Tasks (task bar). To jump into a sketch, select it in the model tree an either double-click on it or right-click on it and then select Edit sketch in the context menu. Another possibility is to click on the toolbar icon (Edit sketch).
The dialog consists of the following sections:
Solver messages
Advanced solver control
This dialog section will only appear if you set the option Show Advanced Solver Control in the Task bar in the sketcher preferences.
You can specify the following:
Name | 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 there something 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 there something 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, a value under the pivot threshold is treated as if it is 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 | With this button the solver will explicitly started. |
Restore Defaults | With this button the default solver settings will be restored. |
Note: Most of the solver parameters are of no practical use. They can however help testing and understanding the solvers.
Edit controls
The edit controls are intended to improve the workflow. They can also globally set for all sketches via the sketcher preferences.
You can set the following controls:
Name | Description |
---|---|
Show Grid | If checked, a grid will be shown in the sketches. |
Grid size | The distance between 2 subsequent grid lines. Note that the default value of 0 mm will result in a 10 mm grid. |
Grid snap | If checked, new points will snap to the nearest grid crossing point. Note that the points have already to be close to a grid crossing point that the snap takes effect.
Please note that this is just a visual aid; grid snap is no substitution for coincidence constraints. |
Auto constraints | If checked, the sketcher proposes automatically sensible constraints. If you draw for example a polyline and point towards the bottom, you will see that the sketcher proposes a vertical constraint:. If you set now a point the drawn line segment will get the vertical constraint. |
Avoid redundant auto constraints | If checked, the sketcher tries not to propose redundant auto constraints. This option only has an effect if also the option Auto constraints is used. |
Rendering oder | The order how sketches are rendered. To change it, drag and drop one of the geometries to the top or bottom. |
Constraints
Elements
- 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
- Getting started
- Installation: Download, Windows, Linux, Mac, Additional components, Docker, AppImage, Ubuntu Snap
- Basics: About FreeCAD, Interface, Mouse navigation, Selection methods, Object name, Preferences, Workbenches, Document structure, Properties, Help FreeCAD, Donate
- Help: Tutorials, Video tutorials
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