Modelling

jSDN includes a powerful NURBS surfaces and curves modeller, with three 2D projection views and a 3D view. NURBS can be modified by moving their control points, scaled, rotated, translated and mirrored. Additional NURBS tools include knot transposition, knot reduction, degree elevation, and tessellation. The NURBS control points visualisation can be modified to show all of them, of just selected U or V rows. In addition it allows managing and editing POLY surfaces (lines and 3-faceted and 4-faceted polyhedrals) which can be imported from standard 3D CAD systems (DXF, STL, 3DS, AC3D, VRML).

The elements of a design can be organised hierarchically, allowing grouping, which makes manageable large designs. Each jSDN element also has some individual properties such as: name, color, visibility (hide/unhide), editability (locked/unlocked), and functional properties (type and subtype). The functional properties indicate the use of a given element, in order to perform the corresponding calculations, allowing for a differentiate treatment of each type. The following types and subtypes are currently supported:

Types	Subtypes
HULL	HULL, DECK
APPENDAGE	RUDDER, KEEL, BULB
SAIL	MAINSAIL, JIB/GENOA, SPINNAKER
RIG	MAST, BOOM, POLE

2D visualisation can be configured to be wireframe or shaded. 3D visualisation can be configured to be wireframe or shaded. 3D coloring can be configured to display design colors, checkers pattern or Gaussian curvature (NURBS surfaces only). In addition, the 3D view can be configured to display coloured axis, grid, and textured sea surface.