Python, unable to add mesh

Hello,
I am trying to apply this code to generate the pasta form, unfortunately I am getting an error : unable to add mesh

Here is the code :
import rhinoscriptsyntax as rs
import math
n_u = 128
n_v = 128
point_list =
polygon_list =

for i in range(0,n_v+1):
v = i / n_v
for j in range(0,n_u+1):
u = j / n_u
#Agnolotti page 016
x = 10.0math.sqrt(math.sin(u/2.0math.pi)+u0.15math.sin(v30.0math.pi))math.cos(v0.95math.pi+0.03math.pi)
y = 10.0* math.sin(u/2.0math.pi)+u0.15math.cos(v30.0math.pi) math.sin(v0.95math.pi+0.03)
z = 5.0math.pow(math.cos(u/2.0math.pi),5)math.sin(vmath.pi)-5.0math.sin(vmath.pi)math.pow(math.cos(u/2.0math.pi),200)
point_list.append ([x,y,z])

angolotti.py (837 Bytes)

for i in range(0,n_v):
for j in range(0,n_u):
p0 = i*(n_u+1)+j
p1 = i*(n_u+1)+j+1
p2 = (i+1)(n_u+1)+j+1
p3 = (i+1)
(n_u+1)+j
polygon_list.append ([p0,p1,p2,p3])
rs.AddMesh(point_list,polygon_list)

Is this related to GHPython? If so, please attach your implementation in a Grasshopper definition and maybe a screenshot of the error you’re getting.

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If this is for Grasshopper you can’t use rhinoscriptsyntax.

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Pasta form.gh (2.1 KB)
Thanks very much for your reply , kindly find the screenshot and the grasshopper file.

You can simply assign the generated mesh directly to an output parameter like so:

PastaForm_AHD.gh (2.5 KB)

Note that the rhinoscriptsyntax methods operate on/return GUIDs (as this module is designed for targeting the Rhino document). However, when outputting to the canvas the PastaMesh variable is automatically cast to its underlying RhinoCommon Mesh object:

So you can use rhinoscriptsyntax, but I generally recommend sticking with straight up RhinoCommon for geometry generation and manipulation in GHPython (for numerous reasons that have been covered here and on the old Grasshopper forum). Though there might be an initially steeper learning curve (which I still don’t really subscribe to, from experience, but again everyone is different etc).

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I am sorry, but I got the same error with your file ! the script didn’t run successfully

Might be a versioning thing, I’m still on Rhino 5. Perhaps one of the Rhino devs can have a look (or someone else with Rhino 6 installed, just to verify).

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Thanks very much for your help !

In Rhino 6 the mesh that’s being added is considered invalid (I don’t know why) and that’s why it’s not added.
Logged: RH-49528

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using rhinocommon, you can get a mesh out, but I’m not sure the final result is correct. As far as the inital error, the rhinocommon method IsValidWIthLog() indicates the following error:
(False, 'ON_Mesh.m_F[0] has degenerate double precision vertex locations.\n')

Not sure if this is the correct interpretation of what you wanted, but here is the rhinocommon version that uses the IsValidWIthLog() to get the “raw” mesh status, then applies some cleanup operations that creates a “valid” mesh. (it still looks incorrect though…)

import rhinoscriptsyntax as rs
import math
import Rhino

n_u = 128
n_v = 128

point_list = []
polygon_list = []
newMesh = Rhino.Geometry.Mesh()

for i in range(0,n_v+1):
  v = i / n_v
  for j in range(0,n_u+1):
    u = j / n_u
    x = 10.0*math.sqrt(math.sin(u/2.0*math.pi)+u*0.15*math.sin(v*30.0*math.pi))*math.cos(v*0.95*math.pi+0.03*math.pi)
    y = 10.0* math.sin(u/2.0*math.pi)+u*0.15*math.cos(v*30.0*math.pi) *math.sin(v*0.95*math.pi+0.03)
    z = 5.0*math.pow(math.cos(u/2.0*math.pi),5)*math.sin(v*math.pi)-5.0*math.sin(v*math.pi)*math.pow(math.cos(u/2.0*math.pi),200)
    #point_list.append ([x,y,z])
    newMesh.Vertices.Add(x, y, z)

for i in range(0,n_v):
  for j in range(0,n_u):
    p0 = i*(n_u+1)+j
    p1 = i*(n_u+1)+j+1
    p2 = (i+1)*(n_u+1)+j+1
    p3 = (i+1)*(n_u+1)+j
    #polygon_list.append ([p0,p1,p2,p3])
    newMesh.Faces.AddFace(p0,p1,p2,p3)
    
print newMesh.IsValidWithLog()
newMesh.Faces.CullDegenerateFaces()
newMesh.Vertices.CullUnused()
newMesh.Vertices.CombineIdentical(True, True)
newMesh.Weld(math.pi)
newMesh.Normals.ComputeNormals()
newMesh.FaceNormals.ComputeFaceNormals()
newMesh.Compact()
print newMesh.IsValidWithLog()

Rhino Version 6 SR11
(6.11.18317.13431, 11/13/2018)

PastaForm_CAH.gh (2.5 KB)

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Thanks very much mr.Hanley, you solved me a huge problem ! :blush: I just don’t know what is Rhinocommon is it a plug in ?

The documentation here will certainly provide a better explanation than I could!



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Hi all,

this is just Rhino 6 being more investigative than Rhino 5, where bad meshes could more easily end into the document. In particular, the first face is unfortunately wrong! And the reason is, that the script only adds QUADS (4-sides faces) but these are definitely not quadrangular faces:

image

These are triangles, and should be added as such!

We can also just keep your script the same, and rescue the position where the wrong quads (collapsed quads) would be added. Here is how:

import rhinoscriptsyntax as rs
import math
import Rhino

n_u = 128
n_v = 128

point_list = []
polygon_list = []

for i in range(0,n_v+1):
  v = i / n_v

  for j in range(0,n_u+1):
    u = j / n_u
    x = 10.0*math.sqrt(math.sin(u/2.0*math.pi)+u*0.15*math.sin(v*30.0*math.pi))*math.cos(v*0.95*math.pi+0.03*math.pi)
    y = 10.0* math.sin(u/2.0*math.pi)+u*0.15*math.cos(v*30.0*math.pi) *math.sin(v*0.95*math.pi+0.03)
    z = 5.0*math.pow(math.cos(u/2.0*math.pi),5)*math.sin(v*math.pi)-5.0*math.sin(v*math.pi)*math.pow(math.cos(u/2.0*math.pi),200)
    point_list.append ([x,y,z])

for i in range(0,n_v):
  for j in range(0,n_u):
    p0 = i*(n_u+1)+j
    p1 = i*(n_u+1)+j+1
    p2 = (i+1)*(n_u+1)+j+1
    p3 = (i+1)*(n_u+1)+j
    
    curr = [p0,p1,p2,p3]
    
    #rescue collapsed quads
    if point_list[curr[3]] == point_list[curr[0]]: curr.remove(curr[3])
    elif point_list[curr[2]] == point_list[curr[3]]: curr.remove(curr[3])
    if point_list[curr[1]] == point_list[curr[2]]: curr.remove(curr[2])
    if point_list[curr[0]] == point_list[curr[1]]: curr.remove(curr[1])
    
    if len (curr) >= 3: polygon_list.append(curr)

PastaMesh = rs.AddMesh(point_list,polygon_list)

PastaForm_fixed.gh (3.4 KB)

These collapsed quads will then interfere with normals calculation, booleans, etc, and just make everything inconsistent in Rhino 5. Rhino 6 goes in the right direction of pointing out the problem.

Thanks,

Giulio


Giulio Piacentino
for Robert McNeel & Associates
giulio@mcneel.com

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