Source code for ddg.optimize.he.functionals.dirichlet_energy

from numpy import linalg as LA

import ddg
from ddg.optimize.he.functional import HalfEdgeFunctional


class DirichletEnergy(HalfEdgeFunctional):
    """
    Computes the combinatorial Dirchlet energy of a half-edge surface.
    """

    def __init__(self, surface, attr_name, attr_dimension=None, boundary_cells=set()):
        super().__init__(
            surface,
            attr_name,
            "verts",
            attr_dimension=attr_dimension,
            boundary_cells=boundary_cells,
        )

    def evaluate(self, x):
        E = 0
        half_edges = ddg.halfedge.single_edges(self.surface)
        for e in half_edges:
            i = e.tail
            j = e.head
            x_i = (
                x[i.interior_cell_index]
                if i.interior_cell_index is not None
                else getattr(i, self.attr_name)
            )
            x_j = (
                x[j.interior_cell_index]
                if j.interior_cell_index is not None
                else getattr(j, self.attr_name)
            )
            E += LA.norm(x_i - x_j) ** 2
        return E