Extruding a 3D surface

Is there a correct way to extrude a 2.5/3D surface? At the moment I’m extruding a 2D surface, then editing the ‘original’ vertices (i.e. those left at z=0) with the shape of my surface:

import numpy as np
from scipy.spatial import Delaunay
import trimesh

# Generate coordinates
x = np.arange(0, 10)
y = np.arange(0, 10)
z = np.random.rand(10,10).round(2)
xx, yy = np.meshgrid(x, y)

# Triangulate
coords = np.vstack(np.dstack((xx, yy)))
tris = Delaunay(coords)

# Mesh
mesh = trimesh.creation.extrude_triangulation(
    vertices=coords, faces=tris.simplices, height=-10
)

# Edit non-extruded verts with correct z values
verts = mesh.vertices.view(np.ndarray)
verts[verts[:,2] == 0, 2] = z.reshape(-1)

mesh.export(file_obj="mesh.ply");

Thanks for Trimesh – it’s very handy to have a pure python mesh library.

[HollowHeartNet]

Dear all,

I also would like to know how to achieve an extrusion for 3D surfaces. Please help. Here an example for a better explanation of my problem:

1.) Input mesh plane:

2.) Output using trimesh extrusion for 2D triangulation (ignoring z values):

3.) Output using the proposed approach of @dt99jay for considering the z values:

4.) Expected result (I used the extrusion function in Blender for this case):

Do you know how I can get the same result such as in 4.) with trimesh or any other python library?

[manuel-koch]

Hi @dylanjkline, for my use-case I only needed to extrude along a straight line.

I tried it by creating a sphere using sphere = trimesh.creation.icosphere(subdivisions=3, radius=2)

The result of my extrude_convex_mesh() creates a convex mesh of the extruded part - i.e. the sphere is still there as-is ( drawn in gray in my screenshot ) and the extruded mesh is “clued” to it ( drawn in red ), but both meshes are not connected.

That may not exactly what you expect it to be - I guess you expect that the extruded part is replacing the “upper” part of the sphere in the example screenshot, which is actually not the case.