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I've been trying to get started with Blender's Python console. So far, I've managed to create vertices and edges without any trouble, but I've encountered an error that search engines aren't getting me anything for, save for the source code that generated it, which is a bit too dense for my knowledge of computer graphics. The below is my code:

import bpy

tgt_name = "MeshName"
x, y, z = 0.0, 0.0, 100.0


def add_vertex(coords):
    mesh.vertices.add(1)
    mesh.vertices[-1].co = coords
    return len(mesh.vertices)-1


def edge(v1, v2):
    mesh.edges.add(1)
    mesh.edges[-1].vertices = [v1, v2]


def face(v):
    mesh.polygons.add(1)
    print(v)
    mesh.polygons[-1].vertices = v


Selection


tgt_obj = bpy.data.objects.get(tgt_name)
bpy.context.view_layer.objects.active = tgt_obj
tgt_obj.select_set(True)
mesh = tgt_obj.data


Required to add vertices


bpy.ops.object.mode_set(mode='OBJECT')


Create a new vertex at the specified coordinates


v1 = add_vertex((x, y, z))
v2 = add_vertex((x, y+100, z))
v3 = add_vertex((x+110, y+20, z+50))


#edge(v1, v2)
face([v3, v2, v1])


Restore to standard settings


bpy.ops.object.mode_set(mode='EDIT')
bpy.ops.mesh.select_mode(type='VERT')

The error, as noted in the title, is:

BM_mesh_bm_from_me: Warning! Bad face in mesh <> at index <>!, skipping

Does anyone have an idea of what could be causing this error? Additionally, if my code contains any issues aside from that, it'd help to point them out so that I don't make similar missteps in the future.

As additional context, this script is intended to be run on an existing mesh - my ultimate goal, here, is to create a script that can be called to generate complex shapes quickly so that I can integrate them into a model. I'm experienced with Python itself, but fairly new to Blender.

Update: Here is code to build a new mesh, from scratch, for anyone looking - it's what I ended up going with. H/T Harry McKenzie.

import bpy

faces = []
verts = []


def vert(x, y, z):
    verts.append((x, y, z))
    return len(verts)-1


def face(verts):
    faces.append(verts)


name = "Generated"


Create a new mesh


mesh = bpy.data.meshes.new(name)
obj = bpy.data.objects.new(name, mesh)
bpy.data.collections['Collection'].objects.link(obj)
bpy.context.view_layer.objects.active = obj


Code for constructing the mesh


x, y, z = 0.0, 0.0, 100.0
v1 = vert(x, y, z)
v2 = vert(x, y+100, z)
v3 = vert(x+110, y+20, z+50)


face((v1,v2,v3))


Finalize new mesh


mesh.from_pydata(verts, [], faces)
mesh.update(calc_edges=True)
mesh.validate(verbose=True)
```
Ooogboog
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  • 3
  • i don't think using the "add" function is correct method to use. usually you would construct a mesh using mesh.from_pydata(coords, edges, faces) or using bmesh. are you open to any method as long as it can construct a mesh via python? Here's the proper way to construct a mesh. – Harry McKenzie Jul 31 '23 at 08:26
  • Creating a mesh from scratch may work, for my purposes, but I'd like to know why my face generation is failing, given that edge and vertex generation seem to work. The second code block in the linked answer seems to construct faces the same way I attempt to do so, by specifying a set of vertex indices. – Ooogboog Jul 31 '23 at 15:10
  • Also - I've edited my original code to construct the same face, and it appears to work. Assuming this is the only (good) way to get dynamically generated objects into the editor, does my implementation look alright? – Ooogboog Jul 31 '23 at 15:52

0 Answers0