Polygon Offsetting

This example demonstrates how to create offset polygons (inward and outward) using COMPAS CGAL.

Key Features:

• Creating inner and outer polygon offsets
• Handling complex polygon shapes
• Color-coded visualization of original and offset polygons

from compas.geometry import Polygon
from compas_viewer import Viewer

from compas_cgal.straight_skeleton_2 import offset_polygon
from compas_cgal.straight_skeleton_2 import offset_polygon_with_holes

points = [
    (-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),
]
polygon = Polygon(points)
offset = 1.5

offset_polygon_inner = offset_polygon(points, offset)
offset_polygon_outer = offset_polygon(points, -offset)


result = offset_polygon_with_holes(offset_polygon_outer[0], offset_polygon_inner, -0.1)

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

viewer = Viewer()
viewer.config.renderer.show_grid = False

viewer.scene.add(polygon, show_faces=False)

for opolygon in offset_polygon_inner:
    viewer.scene.add(
        opolygon,
        linecolor=(1.0, 0.0, 0.0),
        facecolor=(1.0, 0.0, 0.0, 0.0),
        show_faces=False,
    )

for opolygon in offset_polygon_outer:
    viewer.scene.add(
        opolygon,
        linecolor=(0.0, 0.0, 1.0),
        facecolor=(0.0, 0.0, 1.0, 0.0),
        show_faces=False,
    )

for opolygon, holes in result:
    viewer.scene.add(
        opolygon,
        linecolor=(0.0, 0.0, 1.0),
        facecolor=(0.0, 0.0, 1.0, 0.0),
        show_faces=False,
    )
    for hole in holes:
        viewer.scene.add(
            hole,
            linecolor=(0.0, 0.0, 1.0),
            facecolor=(0.0, 0.0, 1.0, 0.0),
            show_faces=False,
        )

viewer.show()