Refine nurbs curve node documentation.

a50195d7 · Ilya Portnov · d2d8abab · a50195d7 · a50195d7
--- a/docs/nodes/curve/curve_index.rst
+++ b/docs/nodes/curve/curve_index.rst
@@ -53,6 +53,7 @@ Curves
   interpolate_nurbs_curve
   insert_knot
   remove_knot
+   refine_nurbs_curve
   remove_excessive_knots
   adaptive_plot_nurbs
   catenary_curve

--- a/docs/nodes/curve/refine_nurbs_curve.rst
+++ b/docs/nodes/curve/refine_nurbs_curve.rst
+Refine NURBS Curve
+==================
+
+Functionality
+-------------
+
+This node performs "refinement" procedure on a NURBS curve, i.e. inserts a
+number of knots in order to make it easier to manipulate with curve's shape.
+Each knot can be inserted once or multiple times. Knots are distributed
+according to one of algorithms, in order to make knots distribution more even.
+
+After some modifications to refined curve shape were done, unneded knots can be
+removed by use of "Remove excessive knots (Curve)" node.
+
+Inputs
+------
+
+This node has the following inputs:
+
+* **Curve**. The NURBS Curve object to be refined. This input is mandatory.
+* **NewKnots**. The number of knots to be inserted. The default value is 10.
+* **Resolution**. Resolution of the algorithm which is used to calculate curve
+  arc lengths (see the documentation of "Curve Length" node, for example).
+  Larger values correspond to better precision, but worse performance. The
+  default value is 50. This input is only available when the **Distribution**
+  parameter is set to **Distribute Length** or **Bisect Length**.
+* **TMin**, **TMax**. Minimum and maximum values of curve's T parameters,
+  between which the new knots are to be inserted. These inputs are available
+  only when the **Specify Segment** parameter is checked. The default values
+  are 0.0 and 1.0, correspondingly.
+
+Parameters
+----------
+
+This node has the following parameters:
+
+* **Distribution**. The algorithm used to distribute curve's knots evenly. The available options are:
+
+  * **Even T**. New knots are distributed evenly in curve's T space, not taking
+    into account the fact that previously existing curve knots can lie near to
+    newly inserted knots. This option is the default.
+  * **Distribute T**. New knots are inserted into each segment between existing
+    curve knots, distributed evenly (in curve's parameter space) inside each
+    segment. The number of knots inserted into each segment is proportional to
+    the span of curve's T parameter, corresponding to the segment.
+  * **Distribute Length**. New knots are inserted into each segment between
+    existing curve knots, distributed evenly (according to curve arc length)
+    inside each segment. The number of knots inserted into each segment is
+    proportional to the curve arc length within the segment.
+  * **Bisect T**. New knot is inserted in the middle (in curve's parameter
+    space) of the segment between existing curve knots, which has the maximum
+    span of curve's T parameter; thus, this segment is subdivided in two
+    smaller ones. The following knot is similarly inserted into the segment
+    which is now largest. The procedure is repeated until the required number
+    of knots is inserted.
+  * **Bisect Length**. New knot is inserted in the middle (in terms of curve arc
+    length) of the segment between existing curve knots, which has the maximum
+    curve arc length; thus, this segment is subdivided in two smaller ones. The
+    following knot is similarly inserted into the segment which is now largest.
+    The procedure is repeated until the required number of knots is inserted.
+
+* **Insert each knot**. This defines the number of times each knot is inserted. The available options are:
+
+  * **Once**. Each knot is inserted one time.
+  * **As possible**. Each knot is inserted as many times as possible; that is,
+    `p-1` times, where `p` is the degree of the curve - if the new knot does
+    not coincide with any of existing knots; or smaller number of times, if the
+    new knot hapens to coincide with previously existing knot. This option is
+    the default.
+
+* **Specify Segment**. If checked, the node allows you to specify the range of
+  curve's T parameter, into which all new knots are inserted. The range is
+  specified by **TMin**, **TMax** inputs. If the parameter is not checked, then
+  new knots will be inserted along the whole curve. Unchecked by default.
+
+Outputs
+-------
+
+This node has the following outputs:
+
+* **Curve**. The resulting NURBS Curve object.
+* **NewKnots**. The values of newly inserted knots.
+
+Example of Usage
+----------------
+
+.. image:: https://user-images.githubusercontent.com/284644/126066221-95589c16-c04d-4b9c-add7-19c6ad4ab906.png
+