copy_from_face_interp needs tuple input, loses reference, returns nothing #120861

New Issue

Dmitry C. · 2024-04-20T20:10:46+02:00

Dmitry C. commented

2024-04-20 20:10:46 +02:00

System: Windows 10
Broken: Blender 2.79 - 4.1.1
Worked: never?

Short description of error
The operation projects data from source face onto target element. Calling it requires wrapping the source face into a tuple, which is unintuitive, likely unintentional and not reflected in the docs.

When projecting face data onto another face, the reference to the target face gets lost (marked dead), and the operation does not return a new reference. This makes the usage impractical. If possible, the face should stay in place, but if not, the op should at least return the new one.

Test code for different element types is below. Depending on the type, the behavior is different.
Faces throw both errors.
Loops don't lose references, but still require tuples.
Verts don't suffer from either of the issues.

BMFace.copy_from_face_interp():

import bmesh; bm = bmesh.new(); bm.loops.layers.uv.verify()
bmesh.ops.create_icosphere(bm, radius=8, calc_uvs=True)
bm.faces.ensure_lookup_table()

src_face, tgt_face = bm.faces[:2]
print(tgt_face.tag)
# False
print(tgt_face.copy_from_face_interp(src_face))
# SystemError: new style getargs format but argument is not a tuple
print(tgt_face.copy_from_face_interp((src_face,)))
# None
print(tgt_face.tag)
# ReferenceError: BMesh data of type BMFace has been removed

BMLoop.copy_from_face_interp():

import bmesh; bm = bmesh.new(); bm.loops.layers.uv.verify()
bmesh.ops.create_icosphere(bm, radius=8, calc_uvs=True)
bm.faces.ensure_lookup_table()

src_face, tgt_loop = bm.faces[0], bm.faces[-1].loops[0]
print(tgt_loop.tag)
# False
print(tgt_loop.copy_from_face_interp(src_face))
# SystemError: new style getargs format but argument is not a tuple
print(tgt_loop.copy_from_face_interp((src_face,)))
# None
print(tgt_loop.tag)
# False

BMVert.copy_from_face_interp():

import bmesh; bm = bmesh.new(); bm.loops.layers.uv.verify()
bmesh.ops.create_icosphere(bm, radius=8, calc_uvs=True)
bm.faces.ensure_lookup_table()

src_face, tgt_vert = bm.faces[0], bm.faces[-1].vert[0]
print(tgt_vert.tag)
# False
print(tgt_vert.copy_from_face_interp(src_face))
# None
print(tgt_vert.tag)
# False

BMVert.copy_from_vert_interp():

import bmesh; bm = bmesh.new(); bm.loops.layers.uv.verify()
bmesh.ops.create_icosphere(bm, radius=8, calc_uvs=True)
bm.verts.ensure_lookup_table()

src_vert1, src_vert2, tgt_vert = bm.verts[0], bm.verts[1], bm.verts[-1]
print(tgt_vert.tag)
# False
print(tgt_vert.copy_from_vert_interp((src_vert1, src_vert2), 0.5))
# None
print(tgt_vert.tag)
# False

Edit: changed test code to be (more) valid. Now the mesh isn't degenerate, has valid UVs, and there's no risk of projecting onto a perpendicular face. Everything still applies though, it's not mesh-specific.

System: Windows 10 Broken: Blender 2.79 - 4.1.1 Worked: never? **Short description of error** The operation projects data from source face onto target element. Calling it requires wrapping the source face into a tuple, which is unintuitive, likely unintentional and not reflected in the docs. When projecting face data onto another face, the reference to the target face gets lost (marked dead), and the operation does not return a new reference. This makes the usage impractical. If possible, the face should stay in place, but if not, the op should at least return the new one. Test code for different element types is below. Depending on the type, the behavior is different. Faces throw both errors. Loops don't lose references, but still require tuples. Verts don't suffer from either of the issues. 1. `BMFace.copy_from_face_interp()`: ```Py import bmesh; bm = bmesh.new(); bm.loops.layers.uv.verify() bmesh.ops.create_icosphere(bm, radius=8, calc_uvs=True) bm.faces.ensure_lookup_table() src_face, tgt_face = bm.faces[:2] print(tgt_face.tag) # False print(tgt_face.copy_from_face_interp(src_face)) # SystemError: new style getargs format but argument is not a tuple print(tgt_face.copy_from_face_interp((src_face,))) # None print(tgt_face.tag) # ReferenceError: BMesh data of type BMFace has been removed ``` 2. `BMLoop.copy_from_face_interp()`: ```Py import bmesh; bm = bmesh.new(); bm.loops.layers.uv.verify() bmesh.ops.create_icosphere(bm, radius=8, calc_uvs=True) bm.faces.ensure_lookup_table() src_face, tgt_loop = bm.faces[0], bm.faces[-1].loops[0] print(tgt_loop.tag) # False print(tgt_loop.copy_from_face_interp(src_face)) # SystemError: new style getargs format but argument is not a tuple print(tgt_loop.copy_from_face_interp((src_face,))) # None print(tgt_loop.tag) # False ``` 3. `BMVert.copy_from_face_interp()`: ```Py import bmesh; bm = bmesh.new(); bm.loops.layers.uv.verify() bmesh.ops.create_icosphere(bm, radius=8, calc_uvs=True) bm.faces.ensure_lookup_table() src_face, tgt_vert = bm.faces[0], bm.faces[-1].vert[0] print(tgt_vert.tag) # False print(tgt_vert.copy_from_face_interp(src_face)) # None print(tgt_vert.tag) # False ``` 4. `BMVert.copy_from_vert_interp()`: ```Py import bmesh; bm = bmesh.new(); bm.loops.layers.uv.verify() bmesh.ops.create_icosphere(bm, radius=8, calc_uvs=True) bm.verts.ensure_lookup_table() src_vert1, src_vert2, tgt_vert = bm.verts[0], bm.verts[1], bm.verts[-1] print(tgt_vert.tag) # False print(tgt_vert.copy_from_vert_interp((src_vert1, src_vert2), 0.5)) # None print(tgt_vert.tag) # False ``` Edit: changed test code to be (more) valid. Now the mesh isn't degenerate, has valid UVs, and there's no risk of projecting onto a perpendicular face. Everything still applies though, it's not mesh-specific.

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Dmitry C. added the

labels 2024-04-20 20:10:47 +02:00

Iliya Katushenock added the