Added some comments

rhinocommon/cs/SampleCsCommands/SampleCsAddNurbsCurve.cs

@@ -10,11 +10,16 @@ public class SampleCsAddNurbsCurve : Command
 
     protected override Result RunCommand(RhinoDoc doc, RunMode mode)
     {
+      // The degree must be >= 1 and the number of control points
       const int degree = 3;
+      // The order is degree + 1
+      const int order = degree + 1;
+      // The number of control points
       const int cv_count = 6;
+      // The number of knots is always (number of control points + degree - 1)
       const int knot_count = cv_count + degree - 1;
-      const int order = degree + 1;
 
+      // Define the "Euclidean" (world 3-D) locations for the control points.
       var cvs = new Point3d[cv_count];
       cvs[0] = new Point3d(0.0, 0.0, 0.0);
       cvs[1] = new Point3d(5.0, 10.0, 0.0);
@@ -23,21 +28,34 @@ protected override Result RunCommand(RhinoDoc doc, RunMode mode)
       cvs[4] = new Point3d(20.0, 0.0, 0.0);
       cvs[5] = new Point3d(25.0, 10.0, 0.0);
 
+      // Define the knots.
+      // Unless you are doing something special, knot vectors should be clamped.
+      // "Clamped" means the first and last degree many knots are the same.
+      // In this example the first three knots are 0 and the last three knots are 3.
+      // The interior knots can have multiplicity from 1 (a "simple" knot)
+      // to degree (a "full multiplicity")
       var knots = new double[knot_count];
+      // Start with a full multiplicity knot
       knots[0] = 0.0;
       knots[1] = 0.0;
       knots[2] = 0.0;
+      // Simple interior knot
       knots[3] = 1.0;
+      // Simple interior knot
       knots[4] = 2.0;
+      // End with a full multiplicity knot
       knots[5] = 3.0;
       knots[6] = 3.0;
       knots[7] = 3.0;
 
+      // Create a non-rational NURBS curve
       var curve = new NurbsCurve(3, false, order, cv_count);
 
+      // Set the control points
       for (int i = 0; i < cv_count; i++)
         curve.Points.SetPoint(i, cvs[i]);
 
+      // Set the knots
       for (int i = 0; i < knot_count; i++)
         curve.Knots[i] = knots[i];
 

rhinocommon/cs/SampleCsCommands/SampleCsNurbsCircle.cs

@@ -1,6 +1,4 @@
-using System;
-using System.Collections.Generic;
-using Rhino;
+using Rhino;
 using Rhino.Commands;
 using Rhino.Geometry;
 
@@ -12,11 +10,16 @@ public class SampleCsNurbsCircle : Command
 
     protected override Result RunCommand(RhinoDoc doc, RunMode mode)
     {
+      // The degree must be >= 1 and the number of control points
       const int degree = 2;
+      // The order is degree + 1
+      const int order = degree + 1;
+      // The number of control points
       const int cv_count = 7;
+      // The number of knots is always (number of control points + degree - 1)
       const int knot_count = cv_count + degree - 1;
-      const int order = degree + 1;
 
+      // Define the "Euclidean" (world 3-D) locations for the control points.
       var points = new Point3d[cv_count];
       points[0] = new Point3d(2.500, 0.000, 0.000);
       points[1] = new Point3d(5.000, 0.000, 0.000);
@@ -25,7 +28,10 @@ protected override Result RunCommand(RhinoDoc doc, RunMode mode)
       points[4] = new Point3d(1.250, 2.165, 0.000);
       points[5] = new Point3d(0.000, 0.000, 0.000);
       points[6] = new Point3d(2.500, 0.000, 0.000);
-
+
+      // Define the weights
+      // Weights must be > 0.
+      // In general you should set the first and last weight to 1.
       var weights = new double[cv_count];
       weights[0] = 1.0;
       weights[1] = 0.5;
@@ -35,24 +41,38 @@ protected override Result RunCommand(RhinoDoc doc, RunMode mode)
       weights[5] = 0.5;
       weights[6] = 1.0;
 
+      // Define the knots.
+      // Unless you are doing something special, knot vectors should be clamped.
+      // "Clamped" means the first and last degree many knots are the same.
+      // In this example the first three knots are 0 and the last three knots are 3.
+      // The interior knots can have multiplicity from 1 (a "simple" knot)
+      // to degree (a "full multiplicity")
       var knots = new double[knot_count];
+      // Start with a full multiplicity knot
       knots[0] = 0.000;
       knots[1] = 0.000;
+      // Full multiplicity interior knot
       knots[2] = 0.333;
       knots[3] = 0.333;
+      // Full multiplicity interior knot
       knots[4] = 0.667;
       knots[5] = 0.667;
+      // End with a full multiplicity knot
       knots[6] = 1.000;
       knots[7] = 1.000;
 
+      // Create a rational NURBS curve
       var curve = new NurbsCurve(3, true, order, cv_count);
 
+      // Set the control points and weights.
+      // Since our curve is rational, we need homogeneous points (4-D
       for (var ci = 0; ci < cv_count; ci++)
       {
         var cv = new Point4d(points[ci].X * weights[ci], points[ci].Y * weights[ci], points[ci].Z * weights[ci], weights[ci]);
         curve.Points.SetPoint(ci, cv);
       }
 
+      // Set the knots
       for (var ki = 0; ki < knot_count; ki++)
         curve.Knots[ki] = knots[ki];