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, impact can sometimes be minimized)
• non degenerate triangle by joining of three quadrangles (functioning prototype, situation is still fluid)

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
• core function: 5 face blending strategy << NEXT FOCUS
• core function: 6 face blending strategy
• core function: automatic G3 'seeking' for 6 point poly based curves and surfaces. There are 2 degrees of freedom remaining, so this is possible in many cases, though not all. Of the possible case, some will result in aesthetically unacceptable solutions. This function can probably use a numerical method instead of an exact algebraic solution.
• core function: raise degree as needed to improve internal continuity (curvature comb breaks at internal knots)
• modeling tool: add control points to curves and surfaces to give additional design freedom away from the seams