Polyhedron tutorial¶

Example of a Polyhedron created extruding a polygon along the z axis from the ground to the Surface

class pyny3d.geoms.Polyhedron(polygons, make_ccw=True, **kwargs)[source]

Represents 3D polygon-based convex polyhedra.

Under the hood, pyny.Polyhedron class uses the pyny.Surface infrastructure to store and operate with the faces (Polygons). This pyny.Surface can be found in Polyhedron.aux_surface.

Instances of this class work as iterable object. When indexed, returns the pyny.Polygons which conform it.

Parameters:	polygons (list of ndarray, list of pyny.Polygon) – Polygons to be set as the Polyhedron. These Polygons have to be contiguous and form a closed polyhedron*. make_ccw (bool) – If True, points will be sorted ccw for each polygon.
Returns:	None

Note

* A concave or open polyhedron will not produce any error and the code will probably work fine but it is important to keep in mind that pyny3d was created to work specifically with convex and closed bodies and you will probably get errors later in other parts of the code.

Warning

This object do NOT check the contiguity of the polygons or whether the polyhedron is closed or not, even it is actually a requirement.

Non-trivial methods¶

As always, you can also use the Polyhedron documentation for method-by-method description.

In this section we are going to see only the .by_two_polygons() method due to the Polyhedron class is pretty simple and has not barely any own methods.

by_two_polygons¶

Static method. This method creates a closed Polyhedron by connecting two polygons. Both polygons must have the same number of vertices. These two polygons can be considered the top and the bottom and the rest of its faces (lateral ones) will be generated by matching the polygons’ vertices two by two.

It is important to note that the given polygons (arguments) can be in pyny.Polygon format or simply in ndarray.

An example:

import numpy as np
import pyny3d.geoms as pyny

poly1 = pyny.Polygon(np.array([[0, 0, 0], [1, 0, 0], [1, 1, 0], [0, 1, 0]]))
poly2 = pyny.Polygon(np.array([[0, 0, 3], [0.5, 0, 3], [0.5, 0.5, 3], [0, 0.5, 3]]))
polyhedron = pyny.Polyhedron.by_two_polygons(poly1, poly2)
polyhedron.plot('b')

Generated Polyhedron by the top and bottom Polygons

Warning

If an error is raised, probably the Polyhedron you are trying to create has non-planar faces.

Next tutorial: Place tutorial