Scripts: capcalc.py

# Get a triangulation of the part of a plane inside a closed surface.

plane_normal = (0,0,1)
plane_offset = 3.0      # Angstroms

# Vertices is N by 3 numpy array of floats giving triangle vertex positions.
# Triagles is T by 3 numpy array of integers giving indices
# into vertex array for 3 vertices of each triangle.
import Icosahedron as icos
vertices, triangles = icos.icosahedron_triangulation(radius = 10)

# Get vertices and triangles for part of plane inside surface
import _surfacecap
cv, ct = _surfacecap.compute_cap(plane_normal, -plane_offset, vertices, triangles)

# compute_cap() uses the sweep-line method that produces long skinny triangles.
# To refine so triangles are not so skinny use refine_mesh()
subdivision_factor = 1
cv, ct = _surfacecap.refine_mesh(cv, ct, subdivision_factor)

print 'Clipped icosahedron, clip plane has', len(ct), 'triangles'