Prisms

Polygons can be associated with arbitrarily complex extrusion rules to form 3D Prisms.

import matplotlib.pyplot as plt
import shapely

from meshwell.cad import cad
from meshwell.mesh import mesh
from meshwell.polyprism import PolyPrism
from meshwell.visualization import plot3D

# We use shapely as an API to enter polygons

# Initialize GMSH and create the mesh
polygon_hull = shapely.Polygon(
    [[0, 0], [2, 0], [2, 2], [0, 2], [0, 0]],
)
polygon_hole1 = polygon_hull.buffer(-0.5, join_style="mitre")
polygon = polygon_hull - polygon_hole1

View the polygons:

# Plot the shapely polygons
plt.figure(figsize=(8, 8))
plt.plot(*polygon.exterior.xy, "b-", label="Polygon 1 exterior")
plt.plot(*polygon.interiors[0].xy, "b--", label="Polygon 1 hole")
plt.axis("equal")
plt.title("Shapely Polygons")
plt.legend()
plt.show()

Mesh a prism by combining with buffers

buffers = {0.0: 0.05, 1.0: -0.05}

poly3D = PolyPrism(
    polygons=polygon,
    buffers=buffers,
    physical_name="my_prism1",
)

entities_list = [poly3D]

cad(
    entities_list=entities_list,
    output_file="prism.xao",
)

output_mesh = mesh(
    dim=3,
    input_file="prism.xao",
    output_file="prism.msh",
    default_characteristic_length=100,
)


# Read and plot the mesh

Info    : Clearing all models and views...
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Info    : [ 80%] Difference - Adding holes                                                                                
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Info    : Writing 'prism.xao'...
Info    : Done writing 'prism.xao'
Info    : Clearing all models and views...
Info    : Done clearing all models and views
Info    : Reading 'prism.xao'...
Info    : Done reading 'prism.xao'

plot3D(output_mesh, title="Interactive 3D Mesh")