Development Plan

Ready (for cubics, partial weight support):

• FreeCAD Sketcher as interface to define NURBS control polygons.
• Control Polygon Objects linked to Sketch(es)
• Cubic Curve object linked to Control Polygons
• Grid objects linked to loops of 3 or 4 Control Polygons (3 curves results in a degenerate grid)
• Surface objects linked to grid objects
• subdividing/segmenting curve and surface objects
• 2 curve corner blending with automatic G2 output
• 2 face seam blending with automatic G2 output
• methods to tune corner and seam blends (G3+ output is sometimes possible)
• method to blend the corner formed by 3 faces (includes a degenerate surface OR aFreeCAD Surface workbench 'Filling' surface, impact can sometimes be minimized)
• method to blend the corner formed by 5 faces (includes a FreeCAD Surface workbench 'Filling' surface, impact can sometimes be minimized)
• cap N sided fillet with non degenerate NStar by joining of N quadrangles. This is intended to fill small holes that are nearly flat. This NStar is G2 to the edges of the hole, but has a serious defect in the center of the star. Use to quickly fill 3, 5, 6...N sided holes between blended edges

Needed:

• convenience: more point on curve methods (at curve intersection, surface intersection, etc)
• convenience: point on surface methods
• convenience: more segmenting methods
• modeling tool: isoline extraction
• modeling tool: crude normal offset. maintains order and pole count.
• modeling tool: add control points to curves and surfaces to give additional design freedom away from the seams (more flexibility in basic/unblended surface design
• core function: a fully G2 "NRing" of surfaces to reduce the size of the hole to fill with an NStar. [exists, but not useful enough yet]
• core function: automatic G3 'seeking' for 6 point poly based curves and surfaces. This function can probably use a numerical method instead of an exact algebraic solution. [exists, but is rarely useful]
• core function: raise degree as needed to improve continuity, both at the seams, and at internal knots.