1. NURBS

LWCAD supports standard NURBS curves and surfaces.

NURBS description on Wikipedia

Nurbs curves and surfaces are implemented in LightWave as Polygon Handler plugins.

NURBS Curve 2

Polygon Handler type name: CUR2 (listed in Polygon Info panel)

Latest version 2 is fully compatible with previous curve types from LWCAD 4.5 and older.

Older curve types are automatically converted when object is loaded.

Lines and curve segments can be joined into a single poly-curve.

Closed curves are supported.

Examples listed below:

NURBS Surfaces

Polygon Handler type name: WSUR (listed in Polygon Info panel)

Two basic surface types:

• flat (F surface)

  • defined by single or more curves

  • first curve defines island, next curves are holes

  • all control point positions must lie on the plane (same as polygon)

• nurbs (N surface)

  • defined by 2-dimensional grid of control points with weights

  • control point positions are not constrained

  • surface can be closed along U or V direction

  • surface can have 2,3 and 4 edges

  • holes are not supported yet

Examples are listed below: