Source code for plugins.sectionize

##  This file is part of pyFormex 1.0.7  (Mon Jun 17 12:20:39 CEST 2019)
##  pyFormex is a tool for generating, manipulating and transforming 3D
##  geometrical models by sequences of mathematical operations.
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Create, measure and approximate cross section of a Formex.
from __future__ import absolute_import, division, print_function

import pyformex as pf
from pyformex.plugins.curve import PolyLine
from pyformex import simple
from pyformex.gui.draw import *
from pyformex.arraytools import isInt

[docs]def connectPoints(F, close=False): """Return a Formex with straight segments connecting subsequent points. F can be a Formex or data that can be turned into a Formex (e.g. an (n,3) array of points). The result is a plex-2 Formex connecting the subsequent points of F or the first point of subsequent elements in case the plexitude of F > 1. If close=True, the last point is connected back to the first to create a closed polyline. """ if not isinstance(F, formex.Formex): F = Formex(F) return formex.connect([F, F], bias=[0, 1], loop=close)
[docs]def centerline(F, dir, nx=2, mode=2, th=0.2): """Compute the centerline in the direction dir. """ bb = F.bbox() x0 = x1 = x0[dir] = bb[0][dir] x1[dir] = bb[1][dir] n = array((0, 0, 0)) n[dir] = nx grid = simple.regularGrid(x0, x1, n, swapaxes=True).reshape((-1, 3)) th *= (x1[dir]-x0[dir])/nx n = zeros((3,)) n[dir] = 1.0 def localCenter(X, P, n): """Return the local center of points X in the plane P,n""" test = abs(X.distanceFromPlane(P, n)) < th # points close to plane if mode == 1: C = X[test].center() elif mode == 2: C = X[test].centroid() return C center = [localCenter(F, P, n) for P in grid] return PolyLine(center)
[docs]def createSegments(F, ns=None, th=None): """Create segments along 0 axis for sectionizing the Formex F.""" bb = F.bbox() print("Bounding box = %s" % bb) if ns is None or th is None: res = askItems([['number of sections', 20], ['relative thickness', 0.1]], 'Sectioning Parameters') if res: ns = int(res['number of sections']) th = float(res['relative thickness']) if isInt(ns) and isinstance(th, float): xmin, ymin, zmin = bb[0] xmax, ymax, zmax = bb[1] xgem, ygem, zgem = A = [xmin, ygem, zgem] B = [xmax, ygem, zgem] segments = Formex([[A, B]]).subdivide(ns) print("Segments: %s" % segments) return ns, th, segments return 0, 0, []
[docs]def sectionize(F, segments, th=0.1, visual=True): """Sectionize a Formex in planes perpendicular to the segments. F is any Formex. segments is a plex-2 Formex. Planes are chosen in each center of a segment, perpendicular to that segment. Then parts of the Formex F are selected in the neighbourhood of each plane. Each part is then approximated by a circle in that plane. th is the relative thickness of the selected part of the Formex. If th = 0.5, that part will be delimited by two planes in the endpoints of and perpendicular to the segments. """ sections = [] ctr = [] diam = [] if visual: clear() linewidth(1) draw(F, color='yellow') linewidth(2) for s in segments: c = 0.5 * (s[0]+s[1]) d = s[1]-s[0] l = length(d) n = d/l t = th*l test = abs(F.distanceFromPlane(c, n)) < th*l test = test.sum(axis=-1) G = if visual: draw(G, color='blue', view=None) pf.canvas.update() print(G) C = D = 2 * G.distanceFromLine(C, n).mean() print("Section Center: %s; Diameter: %s" % (C, D)) sections.append(G) ctr.append(C) diam.append(D) return sections, ctr, diam
[docs]def drawCircles(sections, ctr, diam): """Draw circles as approximation of Formices.""" circle =, 1) cross = Formex(simple.Pattern['plus']).rotate(-90, 1) circles = [] n = len(sections) for i in range(n): C = cross.translate(ctr[i]) B = circle.scale(diam[i]/2).translate(ctr[i]) S = sections[i] clear() draw(S, view='left', wait=False) draw(C, color='red', bbox=None, wait=False) draw(B, color='blue', bbox=None) circles.append(B) return circles
def drawAllCircles(F, circles): clear() linewidth(1) draw(F, color='yellow', view='front') linewidth(2) for circ in circles: bb = circ.bbox() d = (bb[1] - bb[0]) * 0.5 bb[0] -= d bb[1] += d draw(circ, color='blue', bbox=bb) zoomAll() # End