OpenCASCADE

Airfoil sections on their planes in space The wing lofted through them A C-clamp from one sketch Example Prince Rupert's cube: a cube through a cube

A planex2d object lies on a plane in 3D, so its faces and wires become OpenCASCADE shapes as they are: exact lines, arcs, full circles and B-splines with shared vertices. They can be extruded, revolved and lofted into solids or cut from solids, and a sketch can be drawn on the face of a solid with the solid’s edges projected into it. Names, colors and mesh sizes travel with the edges and faces into the solid, where netgen reads them as boundaries, materials and mesh sizes. The export can clean up the geometry on the way out, fit splines, and write arcs for tools that accept nothing else. It needs netgen’s OpenCASCADE (pip install netgen-mesher). Planes are px.Plane objects on these pages; every plane argument also takes netgen’s occ.Axes, so existing netgen code can pass its axes unchanged (see API conventions).

In this section

Export

To OCC shapesFaces, wires and sketches as OpenCASCADE shapes, with names and colors kept.

Export optionsCleanup on the way out, with fitted splines, joined lines and open wires.

Splines as arcsThe chain of arcs planex2d computes with, for tools that accept only lines and arcs.

Modeling

A C-clamp, step by stepA profile drawn with the pen, followed by the frame, screw hole, anvil pad, mesh and STEP file.

Sketching on and projecting 3D geometryA sketch on a face of a solid, with edges projected as targets for a marking groove.

Lofting sectionsNACA sections on planes along the span, lofted into a wing.

Lofts with guide curvesSections cut from guide curves, with a plain and a guided loft.

Everything at a glance

Export	ToOCCShape(), ToOCCFace(), ToOCCWire(), ToOCCWires(), with the cleanup options of Simplify (see Export options)
Solids	px.Pad(profile, length) and px.Pocket(target, profile, length), with length2, dir, reverse and until; OpenCASCADE’s own operations on the exported shapes, such as Extrude and occ.ThruSections
Sketching on solids	px.QuickSketch(face) and px.Sketch(face) on a planar face, sk.Project(edge) for its edges as references (see Placing a sketch)
Back into planex2d	px.FromOCC(shape or file), px.Project(shape, plane), px.Intersect3d(plane, shape)
Drawing	px.Plot3d(objects) in 3D, px.Plot(shape, plane) for a section
Meshing	px.OCCGeometry(face) for netgen (see netgen and NGSolve)