A module for creating geometry and materials of botanical trees. This is a (currently very partial and apparently somewhat incorrect) implementation of "Creation and Rendering of Realistic Trees" (Weber, Penn, 1995).
I intend to refactor the code and generalize its approach, so that the implementation is not a mess of special case formulas.
A tree consists of stems which in turn consists of segments. The tree is defined as several layers of stems (e.g. trunk, branches, twigs), each being created using a different set of parameters.
A stem is more or less S-shaped in Weber/Penn, either bending one way, or one way, then the other.