subdiv_jump.py

# simple subdiv algo
# zeffii | 2015

from mathutils import Vector as V
from math import floor
import re


def produce(verts, polys, iterations, scheme):

    summa = sum(scheme)
    rates = [r/summa for r in scheme]
    first, last = rates[0], 1-(rates[-1])

    v_back, e_back = [], []
    ext_v = v_back.extend
    add_e = e_back.append

    def make_verts(poly):
        local_verts = [V(verts[i]) for i in poly] + [V(verts[poly[0]])]
        final_verts = local_verts

        for n in range(iterations):
            temp_verts = []
            v_ext = temp_verts.extend
            for i in range(len(final_verts)-1):
                v1 = final_verts[i]
                v2 = final_verts[i+1]
                va = v1.lerp(v2, first)
                vb = v1.lerp(v2, last)
                v_ext([va, vb])
            final_verts = temp_verts + [temp_verts[0]]

        return final_verts, []

    for poly in polys:
        if len(poly) > 2:
            new_verts, new_edges = make_verts(poly)
            ext_v(new_verts)
            add_e(new_edges)

    return v_back, e_back


def sv_main(verts=[[]], polygons=[[]], iterations=1, scheme=[[["1,3,1"]]]):
    # scheme can be defined as 1,3,1 or 1-3-1 using Note Node
    verts_out = []
    faces_out = []

    in_sockets = [
        ['v', 'verts', verts],
        ['s', 'polygons', polygons],
        ['s', 'iterations', iterations],
        ['s', 'scheme', scheme]
    ]

    out_sockets = [
        ['v', 'verts', [verts_out]],
        ['s', 'faces', [faces_out]],
    ]

    if verts and verts[0]:
        verts = verts[0]
        if polygons and polygons[0]:
            polygons = polygons[0]
            if scheme and scheme[0] and scheme[0][0]:

                if iterations < 1:
                    iterations = 1
                elif iterations > 5:
                    iterations = 5

                scheme = re.split('[,-]', scheme[0][0][0])
                scheme = [int(c) for c in scheme]

                Verts, Faces = produce(verts, polygons, iterations, scheme)
                verts_out.extend([v[:] for v in Verts])
                faces_out.extend(Faces)

    return in_sockets, out_sockets