planefit PolygonArea v2

import Rhino
import clr
clr.AddReferenceToFile("KangarooSolver.dll")
import KangarooSolver as ks
from System import Array, Double

class PolygonArea(ks.GoalObject):
    def __init__(self, polyline, area, strength=1):
        P = [polyline[i] for i in range(len(polyline)-1 if polyline.IsClosed else len(polyline))]
        self.PPos = Array[Rhino.Geometry.Point3d](P)
        self.Move = Array.CreateInstance(Rhino.Geometry.Vector3d, len(P))
        self.Weighting = Array[Double]([strength] * len(P))
        self.Strength = strength
        self.TargetArea = area

    def Calculate(self, p):
        Array.Clear(self.Move, 0, self.Move.Length)
        Array.Clear(self.Weighting, 0, self.Weighting.Length)

        xfpts = [Rhino.Geometry.Point3d(p[self.PIndex[i]].Position) for i in range(self.PIndex.Length)]
        pfresult, plane = Rhino.Geometry.Plane.FitPlaneToPoints(xfpts)
        if pfresult == Rhino.Geometry.PlaneFitResult.Failure:
            raise RuntimeError("Couldn't fit plane to points")

        xform = Rhino.Geometry.Transform.ChangeBasis(Rhino.Geometry.Plane.WorldXY, plane)
        for pt in xfpts:
            pt.Transform(xform)

        areadoubled = 0
        totallength = 0
        L = self.PIndex.Length
        for i in range(L):
            p1, p2 = xfpts[i], xfpts[(i+1)%L]
            areadoubled += Rhino.Geometry.Vector3d.CrossProduct(
                Rhino.Geometry.Vector3d(p1),
                Rhino.Geometry.Vector3d(p2)).Z
            totallength += p1.DistanceTo(p2)

        normal = plane.Normal
        if areadoubled < 0:
            areadoubled *= -1
            normal *= -1

        areashortage = self.TargetArea - 0.5 * areadoubled
        offset = areashortage / totallength

        for i in range(L):
            nexti = (i+1) % L
            edge = p[self.PIndex[nexti]].Position - p[self.PIndex[i]].Position
            edge.Unitize()
            pressure = offset * Rhino.Geometry.Vector3d.CrossProduct(edge, normal)
            self.Move[i] += pressure
            self.Move[nexti] += pressure
            self.Weighting[i] = self.Strength