io_mesh_stl/blender_utils.py

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   3 #  This program is free software; you can redistribute it and/or
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  10 #  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 #  GNU General Public License for more details.
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  13 #  You should have received a copy of the GNU General Public License
  14 #  along with this program; if not, write to the Free Software Foundation,
  15 #  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  16 #
  17 # ##### END GPL LICENSE BLOCK #####
  18
  19 # <pep8 compliant>
  20
  21
  22 def create_and_link_mesh(name, faces, face_nors, points, global_matrix):
  23     """
  24     Create a blender mesh and object called name from a list of
  25     *points* and *faces* and link it in the current scene.
  26     """
  27
  28     import array
  29     from itertools import chain
  30     import bpy
  31
  32     mesh = bpy.data.meshes.new(name)
  33     mesh.from_pydata(points, [], faces)
  34
  35     if face_nors:
  36         # Note: we store 'temp' normals in loops, since validate() may alter final mesh,
  37         #       we can only set custom lnors *after* calling it.
  38         mesh.create_normals_split()
  39         lnors = tuple(chain(*chain(*zip(face_nors, face_nors, face_nors))))
  40         mesh.loops.foreach_set("normal", lnors)
  41
  42     mesh.transform(global_matrix)
  43
  44     # update mesh to allow proper display
  45     mesh.validate(clean_customdata=False)  # *Very* important to not remove lnors here!
  46
  47     if face_nors:
  48         clnors = array.array('f', [0.0] * (len(mesh.loops) * 3))
  49         mesh.loops.foreach_get("normal", clnors)
  50
  51         mesh.polygons.foreach_set("use_smooth", [True] * len(mesh.polygons))
  52
  53         mesh.normals_split_custom_set(tuple(zip(*(iter(clnors),) * 3)))
  54         mesh.use_auto_smooth = True
  55         mesh.show_edge_sharp = True
  56         mesh.free_normals_split()
  57
  58     mesh.update()
  59
  60     obj = bpy.data.objects.new(name, mesh)
  61     bpy.context.collection.objects.link(obj)
  62     bpy.context.view_layer.objects.active = obj
  63     obj.select_set(True)
  64
  65
  66 def faces_from_mesh(ob, global_matrix, use_mesh_modifiers=False):
  67     """
  68     From an object, return a generator over a list of faces.
  69
  70     Each faces is a list of his vertexes. Each vertex is a tuple of
  71     his coordinate.
  72
  73     use_mesh_modifiers
  74         Apply the preview modifier to the returned liste
  75
  76     triangulate
  77         Split the quad into two triangles
  78     """
  79
  80     import bpy
  81
  82     # get the editmode data
  83     if ob.mode == "EDIT":
  84         ob.update_from_editmode()
  85
  86     # get the modifiers
  87     if use_mesh_modifiers:
  88         depsgraph = bpy.context.evaluated_depsgraph_get()
  89         mesh_owner = ob.evaluated_get(depsgraph)
  90     else:
  91         mesh_owner = ob
  92
  93     # Object.to_mesh() is not guaranteed to return a mesh.
  94     try:
  95         mesh = mesh_owner.to_mesh()
  96     except RuntimeError:
  97         return
  98
  99     if mesh is None:
 100         return
 101
 102     mat = global_matrix @ ob.matrix_world
 103     mesh.transform(mat)
 104     if mat.is_negative:
 105         mesh.flip_normals()
 106     mesh.calc_loop_triangles()
 107
 108     vertices = mesh.vertices
 109
 110     for tri in mesh.loop_triangles:
 111         yield [vertices[index].co.copy() for index in tri.vertices]
 112
 113     mesh_owner.to_mesh_clear()