Mesh.from_pydata error if using numpy array for edges, faces #90268

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Peter Staples · 2021-07-28T18:01:28+02:00

Peter Staples commented

2021-07-28 18:01:28 +02:00

System Information
Ubuntu 18

Blender Version
2.93 and prior

Short description of error
If a numpy array is passed for edges or faces in Mesh.from_pydata get following error:

blender-2.91.2-linux64/2.91/scripts/modules/bpy_types.py", line 488, in from_pydata
    if edges or faces:
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

can alleviate by typecasting to list eg:

faces = list(np.array([[0, 1, 2, 3]]))

but instead suggest a simple fix along lines of:

  @@ -485,14 +485,14 @@
           self.polygons.foreach_set("loop_start", loop_starts)
           self.polygons.foreach_set("vertices", vertex_indices)

- if edges or faces:

  +        if len(edges) or len(faces):
               self.update(

                 - Needed to either:
                 - - Calculate edges that don't exist for polygons.
                 # - Assign edges to polygon loops.
- calc_edges=bool(faces),

  +                calc_edges=bool(len(faces)),

                 # Flag loose edges.
- calc_edges_loose=bool(edges),

  +                calc_edges_loose=bool(len(edges)),
               )
   
       @property

Exact steps for others to reproduce the error

Run this script in the text editor:

import bpy
import numpy as np
from bpy_extras.object_utils import object_data_add
from mathutils import Vector


def add_object(context):
    verts = [
        Vector((-1, 1, 0)),
        Vector((1, 1, 0)),
        Vector((1, -1, 0)),
        Vector((-1, -1, 0)),
    ]

    edges = []
    faces = [[0, 1, 2, 3]]

    verts = np.array(verts)
    edges = np.array(edges)
    faces = np.array(faces)

    mesh = bpy.data.meshes.new(name="New Object Mesh")
    mesh.from_pydata(verts, edges, faces)
    object_data_add(context, mesh, operator=None)


add_object(bpy.context)

**System Information** Ubuntu 18 **Blender Version** 2.93 and prior **Short description of error** If a numpy array is passed for edges or faces in `Mesh.from_pydata` get following error: ``` blender-2.91.2-linux64/2.91/scripts/modules/bpy_types.py", line 488, in from_pydata if edges or faces: ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all() ``` can alleviate by typecasting to list eg: ``` faces = list(np.array([[0, 1, 2, 3]])) ``` but instead suggest a simple fix along lines of: ``` @@ -485,14 +485,14 @@ self.polygons.foreach_set("loop_start", loop_starts) self.polygons.foreach_set("vertices", vertex_indices) ``` - if edges or faces: ``` + if len(edges) or len(faces): self.update( ``` - Needed to either: - - Calculate edges that don't exist for polygons. # - Assign edges to polygon loops. - calc_edges=bool(faces), ``` + calc_edges=bool(len(faces)), ``` # Flag loose edges. - calc_edges_loose=bool(edges), ``` + calc_edges_loose=bool(len(edges)), ) @property ``` **Exact steps for others to reproduce the error** - Run this script in the text editor: ``` import bpy import numpy as np from bpy_extras.object_utils import object_data_add from mathutils import Vector def add_object(context): verts = [ Vector((-1, 1, 0)), Vector((1, 1, 0)), Vector((1, -1, 0)), Vector((-1, -1, 0)), ] edges = [] faces = [[0, 1, 2, 3]] verts = np.array(verts) edges = np.array(edges) faces = np.array(faces) mesh = bpy.data.meshes.new(name="New Object Mesh") mesh.from_pydata(verts, edges, faces) object_data_add(context, mesh, operator=None) add_object(bpy.context) ```

Peter Staples commented

2021-07-28 18:01:28 +02:00

Added subscriber: @PeterStaples