Cut Cut V0.gh (18.0 KB)
So, I have a Pikachu, I like to split it into two parts, the bun and the body.
Now I have the cutter edges as lines and also indexes of the edges.
How can I split the mesh with these two data?
I can do it in many ways, but I really like to know how to split a mesh with its edges.
Thanks!
Edit: This guy is not Pikachu, he is Bulbasaur.
This is not a Pikachu, but a Bulbasaur (Lvl. 1). Itâs the first PokĂ©mon in the PokĂ©dex, if I remember right. 
Yes, you are right! Bulbasaur
Hello
This could be done using some recursive on the topology of faces. Make an array of taken faces.
Take a face
Go to all faces not having a fence edges
Do it until tou are stopped
If you need it I could make a c# script
As Laurent (C#) said.
Plus:
Here a little tool
Not tested a lot, it works here with awful edges BUT it will crash Rhino with big meshes (surely too much recursion)
private void RunScript(Mesh mesh, List<int> edgesIndexes, ref object A)
{
List<List<int>> lst_lst_faces = new List<List<int>>();
bool[] isFacesTaken = new bool[mesh.Faces.Count];
int nextIndex = 0;
int count = 0;
int limit = mesh.Faces.Count * 3;//Surely too much
while (count < limit && NextFace(isFacesTaken, ref nextIndex))
{
List < int> lst_faces = new List<int>{nextIndex};
Recursive(mesh, ref isFacesTaken, ref lst_faces, nextIndex, edgesIndexes);
lst_lst_faces.Add(lst_faces);
count++;
};
//Construction of meshes
List<Mesh> meshes = new List<Mesh>();
foreach (List<int> lst_faces in lst_lst_faces)
{
Mesh newMesh = mesh.DuplicateMesh();
newMesh.Faces.Clear();
foreach (int face in lst_faces)
{
newMesh.Faces.AddFace(mesh.Faces[face]);
}
newMesh.RebuildNormals();
meshes.Add(newMesh);
}
A = meshes;
}
// <Custom additional code>
/// <summary>
/// Recursive method to go from one face to other faces that are not crossing a list of fence edges and faces that are not already taken
/// </summary>
/// <param name="mesh">A mesh</param>
/// <param name="isFacesTaken">Array to know if a face is already taken</param>
/// <param name="lst_faces">List of face for a new mesh</param>
/// <param name="curentFace">Current face index</param>
/// <param name="edgesIndexes">List of index of edges that are fence edges</param>
/// <returns></returns>
void Recursive(Mesh mesh, ref bool[] isFacesTaken, ref List < int> lst_faces, int curentFace, List<int> edgesIndexes)
{
lst_faces.Add(curentFace);
isFacesTaken[curentFace] = true;
int[] facesConnexted = mesh.TopologyEdges.GetEdgesForFace(curentFace);
int[] edgesOnFace = mesh.TopologyEdges.GetEdgesForFace(curentFace);
foreach (int edgeIndex in edgesOnFace)
{
int[] faces = mesh.TopologyEdges.GetConnectedFaces(edgeIndex);
foreach (int faceIndex in faces )
{
if (!isFacesTaken[faceIndex] && !IsInList(edgesIndexes, edgeIndex))
{
Recursive(mesh, ref isFacesTaken, ref lst_faces, faceIndex, edgesIndexes);
}
}
}
}
/// <summary>
/// Return true is index is in list
/// </summary>
/// <param name="list_indexes">List of indexes</param>
/// <param name="index">Index to test</param>
/// <returns>return true if index is on list_indexes</returns>
bool IsInList(List<int> list_indexes, int index)
{
bool output = false;
foreach (int indexTest in list_indexes)
{
if (indexTest == index)
{
output = true;
break;
}
}
return output;
}
/// <summary>
/// Return true is a face is not taken
/// </summary>
/// <param name="isFacesTaken"></param>
/// <param name="nextIndex">Index of next face if return is true</param>
/// <returns>Return true is a face is not taken</returns>
bool NextFace(bool[] isFacesTaken, ref int nextIndex)
{
bool output = false;
for (int i = 0; i < isFacesTaken.Length; i++)
{
if (!isFacesTaken[i])
{
output = true;
nextIndex = i;
break;
}
}
return output;
}Thank you all!
I found this. Seems promising.
I am now trying to implement it with my very very limited C# knowledge.
Hereâs a way simpler Python script that splits a mesh along an edge loop:
"""Splits a mesh along an edge loop."""
__version__ = "0.01 (2023-12-29)"
__author__ = "diff-arch (diff-arch.xyz)"
import Rhino.Geometry as rg
import scriptcontext as sc
import copy
MTOL = sc.doc.ModelAbsoluteTolerance
def get_topo_vertex_indices_rec(mesh, edge, __vindices=[], __count=0):
"""Returns exactly two indices of topology vertices of the mesh
that are closest to the end points of the edge."""
if len(__vindices) == 2 or __count > 1:
return __vindices
curr_indices = copy.deepcopy(__vindices)
end_pts = [edge.From, edge.To]
for i in range(M.TopologyVertices.Count):
pt = rg.Point3d(M.TopologyVertices[i])
if end_pts[len(curr_indices)].DistanceToSquared(pt) < MTOL**2:
curr_indices.append(i)
return get_topo_vertex_indices_rec(
mesh, edge, curr_indices, __count=__count+1
)
if __name__ == "__main__":
edge_indices = []
loop_segments = L.GetSegments()
for segment in loop_segments:
vertex_indices = get_topo_vertex_indices_rec(M, segment)
if len(vertex_indices) != 2:
continue
v1, v2 = vertex_indices
edge_idx = M.TopologyEdges.GetEdgeIndex(v1, v2)
edge_indices.append(edge_idx)
if len(edge_indices) != len(loop_segments):
raise RuntimeError("Unable to detect all loop edges.")
M.UnweldEdge(edge_indices, True)
F = M.ExplodeAtUnweldedEdges()
The mesh has to be fully welded in order for this to work!
Cut Cut V1.gh (24.7 KB)
Hereâs a more capable, improved version of my script!
It now supports multiple loops to split a mesh and it it doesnât rely on a completely welded input mesh any more, which has several benefits. Instead it makes a copy of the input mesh, welds it internally, splits that one with the edge loops, and reinstates the unwelded edges of the initial mesh on the split mesh fragments.
As previously, the edge loops are polylines that correspond to connected mesh edges. Whether they are closed loops or open chains of edges doesnât matter.
Enjoy.
Cut Cut V2.gh (25.6 KB)
For some reason it doesnât work on R8
There is also another way I implemented in order to keep a unique mesh. I added a material index to each face. This allow to subdivide a mesh and keeping the border connected. Binary pattern - #3 by laurent_delrieu
Mesh clustering - #10 by laurent_delrieu
Works fine for me! Itâs been created in Rhino 8 (8.2.23346.13002, 2023-12-12) for macOS.
I guess âunweldingâ isnât âsplittingâ, but:
I copied the script in R7 and it works. Seems to be a Rhino/Python bug in R8 Windows. @eirannejad does I miss something (a library to install ?)
Rhino 8 SR3 2023-12-26 (Rhino 8, 8.3.23360.13001, Git hash:master @ eb46d24144907458c3e3bb82d501b5499b1c4a49)
License type: Commerciale, build 2023-12-26
License details: Cloud Zoo
Windows 10 (10.0.19045 SR0.0) or greater (Physical RAM: 32Gb)
.NET 7.0.1
Computer platform: DESKTOP
Standard graphics configuration.
Primary display and OpenGL: NVIDIA Quadro P2000 (NVidia) Memory: 5GB, Driver date: 3-28-2023 (M-D-Y). OpenGL Ver: 4.6.0 NVIDIA 528.89
> Accelerated graphics device with 4 adapter port(s)
- Windows Main Display attached to adapter port #0
OpenGL Settings
Safe mode: Off
Use accelerated hardware modes: On
Redraw scene when viewports are exposed: On
Graphics level being used: OpenGL 4.6 (primary GPUâs maximum)
Anti-alias mode: 4x
Mip Map Filtering: Linear
Anisotropic Filtering Mode: High
Vendor Name: NVIDIA Corporation
Render version: 4.6
Shading Language: 4.60 NVIDIA
Driver Date: 3-28-2023
Driver Version: 31.0.15.2889
Maximum Texture size: 32768 x 32768
Z-Buffer depth: 24 bits
Maximum Viewport size: 32768 x 32768
Total Video Memory: 5 GB
Rhino plugins that do not ship with Rhino
C:\Program Files\SimLab\Plugins\SimLab 3D PDF From Rhino 6\plugins\SimLabPDFExporter.rhp âSimLab PDF Exporterâ
C:\Users\LaurentDelrieu\AppData\Roaming\McNeel\Rhinoceros\packages\8.0\Grasshopper2\2.0.8715-wip.22923\Grasshopper2Plugin.rhp âGrasshopper2â 2.0.8715.22923
C:\Program Files\Geometry Gym\Rhino8\BullAnt.rhp âbullantâ 1.5.6.0
C:\Program Files\Chaos Group\V-Ray\V-Ray for Rhinoceros 6\VRayForRhino.rhp âV-Ray for Rhinoâ
Rhino plugins that ship with Rhino
C:\Program Files\Rhino 8\Plug-ins\Commands.rhp âCommandsâ 8.3.23360.13001
C:\Program Files\Rhino 8\Plug-ins\rdk.rhp âRenderer Development Kitâ
C:\Program Files\Rhino 8\Plug-ins\AnimationTools.rhp âAnimationToolsâ
C:\Program Files\Rhino 8\Plug-ins\RhinoRenderCycles.rhp âRhino Renderâ 8.3.23360.13001
C:\Program Files\Rhino 8\Plug-ins\rdk_etoui.rhp âRDK_EtoUIâ 8.3.23360.13001
C:\Program Files\Rhino 8\Plug-ins\NamedSnapshots.rhp âSnapshotsâ
C:\Program Files\Rhino 8\Plug-ins\MeshCommands.rhp âMeshCommandsâ 8.3.23360.13001
C:\Program Files\Rhino 8\Plug-ins\RhinoCycles.rhp âRhinoCyclesâ 8.3.23360.13001
C:\Program Files\Rhino 8\Plug-ins\Grasshopper\GrasshopperPlugin.rhp âGrasshopperâ 8.3.23360.13001
C:\Program Files\Rhino 8\Plug-ins\RhinoCode\RhinoCodePlugin.rhp âRhinoCodePluginâ 8.3.23360.13001
C:\Program Files\Rhino 8\Plug-ins\Toolbars\Toolbars.rhp âToolbarsâ 8.3.23360.13001
C:\Program Files\Rhino 8\Plug-ins\3dxrhino.rhp â3Dconnexion 3D Mouseâ
C:\Program Files\Rhino 8\Plug-ins\Displacement.rhp âDisplacementâ
C:\Program Files\Rhino 8\Plug-ins\SectionTools.rhp âSectionToolsâ
Interesting. I guess thereâs no conflict between IronPython and Python 3 then in this case, because itâs a Python 3 script. 
Youâre running Rhino 8.3! Is this a nightly build? Iâm on Rhino 8.2, which seems to be the current version for macOS.
Hi this bug is in my Rhino8 too.(in python script)windows 11 rhino_sr4
cut mesh by edge V0.gh (1.1 MB)
Thank you all for your help!
I found one works exceptionally well. It was written by @Rh-3d-p. I cannot find the original post.
Here I use projected curve, but you can also use edge loops.
Not tested in R8.
private void RunScript(Mesh M, List Edges, ref object Mout)
{PolylineCurve pullcrv = new PolylineCurve(); List<PolylineCurve> polylinecrv = new List<PolylineCurve>(); for (int i = 0; i < Edges.Count; i++) { pullcrv = M.PullCurve(Edges[i], 0.001); polylinecrv.Add((PolylineCurve) pullcrv); } Mesh[] meshsplit = M.SplitWithProjectedPolylines(polylinecrv, 0.001); Mout = meshsplit;
Not at all: Recursion is kinda riding (WOT) a proper Ducati: do it wrongly and hospital/morgue is waiting for you.
Do:
Mastermind a way to define (as test cases etc) Edge indices paths (and checkâm ⊠for validity).
Then make the FF/FE conn trees and ride that Ducati (who wants to live for ever?).
Tip: avoid any 999 (uglier Duc ever)
Moral: Ducati Uber Alles
Thanks Peter, I know the way you are doing things. I do it quite the same for others tools I have but it is always interesting to see the way you code as you exploit more .Net/Linq methods than me.
My recursive way for each face was just a lazy/easy way to implement it.
Anyway ⊠when walking the Recursion walk try to use a (public) Tree (instead of loading again and again some growing List [of Face indices in this case]). Thatâs mem (heap) efficient plus itâs also handy for animations (i.e. viz the progress/Loops - so to speak).
Say:
BTW: In the above C# (the 2nd, that is) Iâve used a different approach: start from any face index, grow and then ⊠either get this âpartâ of the Mesh or the other(s) [ case: more than one valid edge paths]. The only tricky thing is the validation of paths (if they are wrong youâll get - obviously - bananas). Thatâs why using a Plane (in the 1st C#) is - more or less - safe (Karma helps as well).
Cut Cut V2 Error.gh (19.6 KB)
Thank you very much!
But it shows an error at my end.
I am using the latest version of Rhino 7.
- Solution exception:âGuidâ object has no attribute âGetSegmentsâ
