object_fracture_cell/fracture_cell_calc.py

   1 # SPDX-License-Identifier: GPL-2.0-or-later
   2
   3 # Script copyright (C) Blender Foundation 2012
   4
   5
   6 def points_as_bmesh_cells(
   7         verts,
   8         points,
   9         points_scale=None,
  10         margin_bounds=0.05,
  11         margin_cell=0.0,
  12 ):
  13     from math import sqrt
  14     import mathutils
  15     from mathutils import Vector
  16
  17     cells = []
  18
  19     points_sorted_current = [p for p in points]
  20     plane_indices = []
  21     vertices = []
  22
  23     if points_scale is not None:
  24         points_scale = tuple(points_scale)
  25     if points_scale == (1.0, 1.0, 1.0):
  26         points_scale = None
  27
  28     # there are many ways we could get planes - convex hull for eg
  29     # but it ends up fastest if we just use bounding box
  30     if 1:
  31         xa = [v[0] for v in verts]
  32         ya = [v[1] for v in verts]
  33         za = [v[2] for v in verts]
  34
  35         xmin, xmax = min(xa) - margin_bounds, max(xa) + margin_bounds
  36         ymin, ymax = min(ya) - margin_bounds, max(ya) + margin_bounds
  37         zmin, zmax = min(za) - margin_bounds, max(za) + margin_bounds
  38         convexPlanes = [
  39             Vector((+1.0, 0.0, 0.0, -xmax)),
  40             Vector((-1.0, 0.0, 0.0, +xmin)),
  41             Vector((0.0, +1.0, 0.0, -ymax)),
  42             Vector((0.0, -1.0, 0.0, +ymin)),
  43             Vector((0.0, 0.0, +1.0, -zmax)),
  44             Vector((0.0, 0.0, -1.0, +zmin)),
  45         ]
  46
  47     for i, point_cell_current in enumerate(points):
  48         planes = [None] * len(convexPlanes)
  49         for j in range(len(convexPlanes)):
  50             planes[j] = convexPlanes[j].copy()
  51             planes[j][3] += planes[j].xyz.dot(point_cell_current)
  52         distance_max = 10000000000.0  # a big value!
  53
  54         points_sorted_current.sort(key=lambda p: (p - point_cell_current).length_squared)
  55
  56         for j in range(1, len(points)):
  57             normal = points_sorted_current[j] - point_cell_current
  58             nlength = normal.length
  59
  60             if points_scale is not None:
  61                 normal_alt = normal.copy()
  62                 normal_alt.x *= points_scale[0]
  63                 normal_alt.y *= points_scale[1]
  64                 normal_alt.z *= points_scale[2]
  65
  66                 # rotate plane to new distance
  67                 # should always be positive!! - but abs incase
  68                 scalar = normal_alt.normalized().dot(normal.normalized())
  69                 # assert(scalar >= 0.0)
  70                 nlength *= scalar
  71                 normal = normal_alt
  72
  73             if nlength > distance_max:
  74                 break
  75
  76             plane = normal.normalized()
  77             plane.resize_4d()
  78             plane[3] = (-nlength / 2.0) + margin_cell
  79             planes.append(plane)
  80
  81             vertices[:], plane_indices[:] = mathutils.geometry.points_in_planes(planes)
  82             if len(vertices) == 0:
  83                 break
  84
  85             if len(plane_indices) != len(planes):
  86                 planes[:] = [planes[k] for k in plane_indices]
  87
  88             # for comparisons use length_squared and delay
  89             # converting to a real length until the end.
  90             distance_max = 10000000000.0  # a big value!
  91             for v in vertices:
  92                 distance = v.length_squared
  93                 if distance_max < distance:
  94                     distance_max = distance
  95             distance_max = sqrt(distance_max)  # make real length
  96             distance_max *= 2.0
  97
  98         if len(vertices) == 0:
  99             continue
 100
 101         cells.append((point_cell_current, vertices[:]))
 102         del vertices[:]
 103
 104     return cells