https://developer.rhino3d.com/api/RhinoCommon/html/M_Rhino_Geometry_Surface_Extend.htm
For directions to extend, we have the IsoStatus enumeration:
https://developer.rhino3d.com/api/RhinoCommon/html/T_Rhino_Geometry_IsoStatus.htm
Just wanted to confirm -
- East is always the edge along the V direction at the positive end of the U domain
- West is always the edge along the V direction at the negative end of U domain
- North is always the edge along the U direction at the positive end of V domain
- South is always the edge along the U direction at the negative end of V domain
Did I get that right? Is it always consistent?