"Interpolate NURBS Curve" node - FreeCAD implementation

docs/nodes/curve/interpolate_nurbs_curve.rst

@@ -4,18 +4,28 @@ Interpolate NURBS Curve
 Dependencies
 ------------
 
-This node can optionally use Geomdl_ library.
+This node can optionally use Geomdl_ or FreeCAD_ library to work.
 
 .. _Geomdl: https://onurraufbingol.com/NURBS-Python/
+.. _FreeCAD: https://www.freecad.org/
 
 Functionality
 -------------
 
 This node builds a NURBS_ Curve object, which goes through all specified points.
 
-In fact, the generated curve always will be a non-rational curve, which means
+The generated curve always will be a non-rational curve, which means
 that all weights will be equal to 1.
 
+Exact final curve degree can be specified for the built-in Sverchok and Geomdl implementations.
+
+FreeCAD does not offer such parameter since the final curve will always be of degree 3 
+(except we interpolate 2 or 3 points without specifying tangents).
+
+FreeCAD implementation offers control with explicit knots and per point tangents.
+The final curve can be set as open or smoothly closed.
+Continuity of the spline defaults to C2. However, if Cyclic is enabled, or Tangents are supplied, the continuity will drop to C1.
+
 .. _NURBS: https://en.wikipedia.org/wiki/Non-uniform_rational_B-spline
 
 Inputs
@@ -24,44 +34,67 @@ Inputs
 This node has the following inputs:
 
 * **Vertices**. The points through which the curve should go. This input is mandatory.
-* **Degree**. Degree of the curve to be generated. The default value is 3.
+* **Degree**. Degree of the curve to be generated. Available only for Sverchok and Geomdl implementations. The default value is 3.
+* **Knots**. The knot sequence. Available only for the FreeCAD implementation and if the "Explicit Knots" method is used.
+  Must contain unique floats in an ascending order. When not connected, the curve will be
+  calculated using "Euclidean" metric. If "Cyclic" is enabled one extra knot must be appended.
+* **Tangents**. Custom tangents can be specified per point. Available only for the FreeCAD implementation if "Tangent Constrains" is enabled and "Mode" is set to "All Tangents".
+* **TangentsMask**. List of booleans to activate or deactivate the corresponding tangent constraints. Available only for the FreeCAD implementation if "Tangent Constrains" is enabled and "Mode" is set to "All Tangents".
+* **InitialTangent**. Set the tangent at the beginning of the curve. Available only for the FreeCAD implementation if "Tangent Constrains" is enabled and "Mode" is set to "Endpoint Tangents".
+* **FinalTangent**. Set the tangent at the end of the curve. Available only for the FreeCAD implementation if "Tangent Constrains" is enabled and "Mode" is set to "Endpoint Tangents".
+* **Tolerance**. Maximal distance of the built curve from the init "Vertices". Available only for the FreeCAD implementation. Default value is 0.0.
 
 Parameters
 ----------
 
 This node has the following parameters:
 
-* **Implementation**. This parameter is available only if **Interpolation
-  mode** parameter is set to **BSpline**. This defines the implementation of
-  NURBS mathematics to be used. The available options are:
+* **Implementation**. Approximation algorithm implementation to be used. The available values are:
 
-  * **Geomdl**. Use Geomdl_ library. This option is available only when Geomdl
-    package is installed.
+  * **Geomdl**. Use the implementation from Geomdl library. This is available only when Geomdl library is installed.
   * **Sverchok**. Use built-in Sverchok implementation.
+  * **FreeCAD**. Use the implementation from FreeCAD library. This is available only when FreeCAD library is installed.
 
-  In general (with large number of control points), built-in implementation
-  should be faster; but Geomdl implementation is better tested.
-  The default option is **Geomdl**, when it is available; otherwise, built-in
-  implementation is used.
+  In general (with large number of control points), FreeCAD implementation will be the fastest. The built-in implementation
+  should be faster than Geomdl, but Geomdl implementation is better tested.
+
+  By default, the first available implementation is used.
 
-* **Centripetal**. This parameter is available only when **Implementation**
-  parameter is set to **Geomdl**. This defines whether the node will use
+* **Centripetal**. This parameter is available only when "Implementation"
+  parameter is set to "Geomdl". This defines whether the node will use
   centripetal interpolation method. Unchecked by default.
-* **Cyclic**. This parameter is available only when **Implementation**
-  parameter is set to **Sverchok**. If checked, then the node will generate
+
+* **Cyclic**. This parameter is available only when "Implementation"
+  parameter is set to "Sverchok" or "FreeCAD". If checked, then the node will generate
   cyclic (closed) curve. Unchecked by default.
-* **Metric**. This parameter is available only when **Implementation**
-  parameter is set to **Sverchok**. This defines the metric used to calculate
-  curve's T parameter values corresponding to specified curve points. The
-  available values are:
+
+* **Method**. Interpolation algorithm to be used for calculating the knots. Available only for the FreeCAD implementation. The available values are:
+
+  * **Parametrization**. Automatic knot sequence generation using certain metric.
+  * **Explicit Knots**. Enables custom knot sequence input. The knots list can be also provided with the use of the `Generate Knotvector <https://nortikin.github.io/sverchok/docs/nodes/curve/generate_knotvector.html>`_ node based on the metrics from it. Note that for closed/cyclic curves the knot sequence needs one additional knot value. 
+
+* **Metric**. This defines the metric used to calculate curve's T parameter values corresponding to specified curve points.
+  Available only when "Implementation" parameter is set to "Sverchok" or "FreeCAD". The available values are:
+
+  * **Manhattan** metric is also known as Taxicab metric or rectilinear distance.
+  * **Euclidean** also known as Chord-Length or Distance metric. The parameters of the points are proportionate to the distances between them.
+  * **Points** also known as Uniform metric. The parameters of the points are distributed uniformly. Just the number of the points from the beginning.
+  * **Chebyshev** metric is also known as Chessboard distance.
+  * **Centripetal** The parameters of the points are proportionate to square roots of distances between them.
+  * **X, Y, Z axis** Use distance along one of coordinate axis, ignore others.
+
+  The default value is Euclidean.
 
-   * Manhattan
-   * Euclidean
-   * Points (just number of points from the beginning)
-   * Chebyshev
-   * Centripetal (square root of Euclidean distance).
+* **Tangent Constraints**. This enables specifying tangent vectors at the interpolation points.
+  Available only when "Implementation" parameter is set to "FreeCAD".
 
-The default value is Euclidean.
+* **Mode**. Constraints mode to be used. Available only when "Implementation" parameter is set to "FreeCAD" and if "Tangent Constraints" is enabled.
+  The available values are:
+
+  * **Endpoint Tangents**. Set the tangents at the beginning and the end of the curve.
+  * **All Tangents**. Set list of tangent vectors for every single interpolation point.
+
+* **Autoscale Tangents**. Set an automatic scale of all active tangents. Available only when "Implementation" parameter is set to "FreeCAD" and if "Tangent Constraints" is enabled.
 
 Outputs
 -------
@@ -77,3 +110,16 @@ Example of usage
 
 .. image:: https://user-images.githubusercontent.com/284644/86528977-4a71de80-bec6-11ea-99bc-9ba8dab027dd.png
 
+Example of the FreeCAD implementation generated cyclic curve with Euclidean parametrization:
+
+.. image:: https://user-images.githubusercontent.com/66558924/218280327-2f215c33-7d8f-401a-bc20-ea60d1213f3a.jpg
+
+Example of the FreeCAD implementation generated open curve with constrained start and end tangents.:
+
+.. image:: https://user-images.githubusercontent.com/66558924/218280333-e12de8c8-0abe-4fbd-b66b-1e7d7ca7d2c9.jpg
+
+Example of the FreeCAD implementation generated cyclic curve using full tangent constraints and custom knots.:
+
+.. image:: https://user-images.githubusercontent.com/66558924/218280648-ca635cbf-8d81-4acc-8dd7-e09a4e3ab364.jpg
+
+

index.yaml

@@ -88,7 +88,7 @@
     - Curve NURBS:
         - SvExNurbsCurveNode
         - SvApproxNurbsCurveMk3Node
-        - SvExInterpolateNurbsCurveNode
+        - SvExInterpolateNurbsCurveNodeMK2
         - SvFilletCurveNode
         - SvDeconstructCurveNode
         - SvNurbsCurveNodesNode

menus/full_by_data_type.yaml

@@ -265,7 +265,7 @@
         - icon_name: EVENT_N
         - SvExNurbsCurveNode
         - SvApproxNurbsCurveMk3Node
-        - SvExInterpolateNurbsCurveNode
+        - SvExInterpolateNurbsCurveNodeMK2
         - ---
         - SvGenerateKnotvectorNode
     - Modify Curve:

menus/full_nortikin.yaml

@@ -90,7 +90,7 @@
             - icon_name: MESH_CUBE
             - SvExNurbsCurveNode
             - SvApproxNurbsCurveMk3Node
-            - SvExInterpolateNurbsCurveNode
+            - SvExInterpolateNurbsCurveNodeMK2
         - GC SCRIPTED:
             - icon_name: PLUGIN
             - SvExCurveFormulaNode