Straight Skeleton with Holes

This example demonstrates how to compute the straight skeleton of a polygon with holes using COMPAS CGAL.

Key Features:

• Computing straight skeleton for polygons with holes

• Handling multiple interior holes

• Color-coded visualization of different edge types

• Distinction between inner bisectors and regular edges

from compas.geometry import Polygon
from compas_viewer import Viewer
from line_profiler import profile

from compas_cgal.straight_skeleton_2 import interior_straight_skeleton_with_holes


@profile
def main():
    """Compute the interior straight skeleton of a polygon with holes."""

    # Outer boundary
    points_boundary = [
        (-1.91, 3.59, 0.0),
        (-5.53, -5.22, 0.0),
        (-0.39, -1.98, 0.0),
        (2.98, -5.51, 0.0),
        (4.83, -2.02, 0.0),
        (9.70, -3.63, 0.0),
        (12.23, 1.25, 0.0),
        (3.42, 0.66, 0.0),
        (2.92, 4.03, 0.0),
        (-1.91, 3.59, 0.0),
    ]
    boundary = Polygon(points_boundary)

    # Inner holes
    holes = [
        [(0.42, 0.88, 0.0), (1.1, -1.0, 0.0), (-1.97, -0.93, 0.0), (-1.25, 1.82, 0.0)],
        [(4.25, -0.64, 0.0), (2.9, -3.03, 0.0), (2.12, -2.16, 0.0), (2.89, -0.36, 0.0)],
        [(10.6, 0.29, 0.0), (9.48, -1.54, 0.0), (5.48, -1.26, 0.0), (5.98, -0.04, 0.0)],
    ]
    holes = [Polygon(hole) for hole in holes]

    graph = interior_straight_skeleton_with_holes(boundary, holes)

    return graph


graph = main()

# ==============================================================================
# Visualize
# ==============================================================================

viewer = Viewer()

for edge in graph.edges():
    line = graph.edge_line(edge)
    if graph.edge_attribute(edge, "inner_bisector"):
        viewer.scene.add(line, linecolor=(1.0, 0.0, 0.0), linewidth=2)
    elif graph.edge_attribute(edge, "bisector"):
        viewer.scene.add(line, linecolor=(0.0, 0.0, 1.0))
    else:
        viewer.scene.add(line, linecolor=(0.0, 0.0, 0.0))

viewer.show()