object_print3d_utils/mesh_helpers.py

   1 # SPDX-License-Identifier: GPL-2.0-or-later
   2
   3 # Generic helper functions, to be used by any modules.
   4
   5
   6 import bmesh
   7
   8
   9 def bmesh_copy_from_object(obj, transform=True, triangulate=True, apply_modifiers=False):
  10     """Returns a transformed, triangulated copy of the mesh"""
  11
  12     assert obj.type == 'MESH'
  13
  14     if apply_modifiers and obj.modifiers:
  15         import bpy
  16         depsgraph = bpy.context.evaluated_depsgraph_get()
  17         obj_eval = obj.evaluated_get(depsgraph)
  18         me = obj_eval.to_mesh()
  19         bm = bmesh.new()
  20         bm.from_mesh(me)
  21         obj_eval.to_mesh_clear()
  22     else:
  23         me = obj.data
  24         if obj.mode == 'EDIT':
  25             bm_orig = bmesh.from_edit_mesh(me)
  26             bm = bm_orig.copy()
  27         else:
  28             bm = bmesh.new()
  29             bm.from_mesh(me)
  30
  31     # TODO. remove all customdata layers.
  32     # would save ram
  33
  34     if transform:
  35         matrix = obj.matrix_world.copy()
  36         if not matrix.is_identity:
  37             bm.transform(matrix)
  38             # Update normals if the matrix has no rotation.
  39             matrix.translation.zero()
  40             if not matrix.is_identity:
  41                 bm.normal_update()
  42
  43     if triangulate:
  44         bmesh.ops.triangulate(bm, faces=bm.faces)
  45
  46     return bm
  47
  48
  49 def bmesh_from_object(obj):
  50     """Object/Edit Mode get mesh, use bmesh_to_object() to write back."""
  51     me = obj.data
  52
  53     if obj.mode == 'EDIT':
  54         bm = bmesh.from_edit_mesh(me)
  55     else:
  56         bm = bmesh.new()
  57         bm.from_mesh(me)
  58
  59     return bm
  60
  61
  62 def bmesh_to_object(obj, bm):
  63     """Object/Edit Mode update the object."""
  64     me = obj.data
  65
  66     if obj.mode == 'EDIT':
  67         bmesh.update_edit_mesh(me, loop_triangles=True)
  68     else:
  69         bm.to_mesh(me)
  70         me.update()
  71
  72
  73 def bmesh_calc_area(bm):
  74     """Calculate the surface area."""
  75     return sum(f.calc_area() for f in bm.faces)
  76
  77
  78 def bmesh_check_self_intersect_object(obj):
  79     """Check if any faces self intersect returns an array of edge index values."""
  80     import array
  81     import mathutils
  82
  83     if not obj.data.polygons:
  84         return array.array('i', ())
  85
  86     bm = bmesh_copy_from_object(obj, transform=False, triangulate=False)
  87     tree = mathutils.bvhtree.BVHTree.FromBMesh(bm, epsilon=0.00001)
  88     overlap = tree.overlap(tree)
  89     faces_error = {i for i_pair in overlap for i in i_pair}
  90
  91     return array.array('i', faces_error)
  92
  93
  94 def bmesh_face_points_random(f, num_points=1, margin=0.05):
  95     import random
  96     from random import uniform
  97
  98     # for pradictable results
  99     random.seed(f.index)
 100
 101     uniform_args = 0.0 + margin, 1.0 - margin
 102     vecs = [v.co for v in f.verts]
 103
 104     for _ in range(num_points):
 105         u1 = uniform(*uniform_args)
 106         u2 = uniform(*uniform_args)
 107         u_tot = u1 + u2
 108
 109         if u_tot > 1.0:
 110             u1 = 1.0 - u1
 111             u2 = 1.0 - u2
 112
 113         side1 = vecs[1] - vecs[0]
 114         side2 = vecs[2] - vecs[0]
 115
 116         yield vecs[0] + u1 * side1 + u2 * side2
 117
 118
 119 def bmesh_check_thick_object(obj, thickness):
 120     import array
 121     import bpy
 122
 123     # Triangulate
 124     bm = bmesh_copy_from_object(obj, transform=True, triangulate=False)
 125
 126     # map original faces to their index.
 127     face_index_map_org = {f: i for i, f in enumerate(bm.faces)}
 128     ret = bmesh.ops.triangulate(bm, faces=bm.faces)
 129     face_map = ret["face_map"]
 130     del ret
 131     # old edge -> new mapping
 132
 133     # Convert new/old map to index dict.
 134
 135     # Create a real mesh (lame!)
 136     context = bpy.context
 137     layer = context.view_layer
 138     scene_collection = context.layer_collection.collection
 139
 140     me_tmp = bpy.data.meshes.new(name="~temp~")
 141     bm.to_mesh(me_tmp)
 142     obj_tmp = bpy.data.objects.new(name=me_tmp.name, object_data=me_tmp)
 143     scene_collection.objects.link(obj_tmp)
 144
 145     layer.update()
 146     ray_cast = obj_tmp.ray_cast
 147
 148     EPS_BIAS = 0.0001
 149
 150     faces_error = set()
 151     bm_faces_new = bm.faces[:]
 152
 153     for f in bm_faces_new:
 154         no = f.normal
 155         no_sta = no * EPS_BIAS
 156         no_end = no * thickness
 157         for p in bmesh_face_points_random(f, num_points=6):
 158             # Cast the ray backwards
 159             p_a = p - no_sta
 160             p_b = p - no_end
 161             p_dir = p_b - p_a
 162
 163             ok, _co, no, index = ray_cast(p_a, p_dir, distance=p_dir.length)
 164
 165             if ok:
 166                 # Add the face we hit
 167                 for f_iter in (f, bm_faces_new[index]):
 168                     # if the face wasn't triangulated, just use existing
 169                     f_org = face_map.get(f_iter, f_iter)
 170                     f_org_index = face_index_map_org[f_org]
 171                     faces_error.add(f_org_index)
 172
 173     bm.free()
 174
 175     scene_collection.objects.unlink(obj_tmp)
 176     bpy.data.objects.remove(obj_tmp)
 177     bpy.data.meshes.remove(me_tmp)
 178
 179     layer.update()
 180
 181     return array.array('i', faces_error)
 182
 183
 184 def face_is_distorted(ele, angle_distort):
 185     no = ele.normal
 186     angle_fn = no.angle
 187
 188     for loop in ele.loops:
 189         loopno = loop.calc_normal()
 190
 191         if loopno.dot(no) < 0.0:
 192             loopno.negate()
 193
 194         if angle_fn(loopno, 1000.0) > angle_distort:
 195             return True
 196
 197     return False