Introduction

The pyddg is a python library for projective geometry, discrete differential geometry, and its visualization in blender. It provides

• datastructures for discrete surfaces:

  • Indexed face set

    • conversion to and from obj

  • Half-edge data structure

    • subdivision

    • Edge-flip algorithm to obtain Delaunay tessellation

  • Nets

    • smooth nets (parametrized curves and surfaces)

      • sampling of smooth nets

    • discrete nets (discrete curves and quadrilateral meshes)

• a framework for projective geometry and subgeometries:

  • projective subspaces

    • homogeneous coordinates

    • dualization

  • quadrics

    • projective and affine normalization

    • parametrization (conversion to smooth net)

  • Geometries and models

    • Cayley-Klein geometries

    • conversion of projective subspaces between different models of geometries

• an interface to blender:

  • blender bridge for nets and half-edge datastructure

• an update mechanism for parameter dependent and interdepent objects (including corresponding objects in blender)