Editing NURBS Editing Support

The Ayam editor is a BSD licensed, Tcl/Tk based modeler for NURBS.  (More background...)

Note that editing NURBS in Archer/MGED should not assume OpenGL surface representations of NURBS are available - that would require the completion of the NURBS tessellation task and in any case not all editing environments provide working OpenGL.  Editing should be possible using wireframe representations of key features, and be mappable to more sophisticated OpenGL based visualization once it appears.  Main tasks would be 1) identifying key features used by Ayam to alter NURBS (knot insertion, etc) and mapping those operations to openNURBS calls (or identifying that the equivalent routine doesn't exist in openNURBS and will need to be ported/reimplemented from Ayam) 2) implementing librt/libged logic to allow those calls to be made 3) implementing appropriate graphical controls and interface logic in Archer (other primitives will provide examples).