compas_cgal.straight_skeleton_2 ¤

Functions:¤

extrude ¤

extrude(
    points, holes=None, weights=None, angles=None, maximum_height=None
) -> tuple[Mesh, list[Line]]

Extrude a 2D polygon into a closed 3D roof mesh using the straight skeleton.

This turns a building footprint into roof-like geometry. Each contour edge sweeps inwards (and upwards) at a speed controlled by either straight skeleton weights or taper angles. A uniform weight of 1 (or an angle of 45 degrees) produces a standard 45 degree hip roof.

The result is ready to display: the returned mesh is triangulated so it renders correctly (even for non-convex roof faces), and the returned lines are the true roof edges (eaves, hips and ridges) to draw on top. A minimal visualization is::

mesh, lines = extrude(polygon, angles=45.0)
viewer.scene.add(mesh, show_lines=False)
for line in lines:
    viewer.scene.add(line)

Parameters:

Name	Type	Description	Default
`points`	sequence[point] \| :class:`compas.geometry.Polygon`	The points of the outer boundary polygon.	required
`holes`	`sequence[sequence[point]]`	The holes of the polygon, each as a sequence of points.	`None`
`weights`	`float \| sequence`	Straight skeleton edge weights. A single value applied to every edge, one value per edge across all contours, or one sequence of edge values per contour (outer boundary first, then holes). Mutually exclusive with `angles`.	`None`
`angles`	`float \| sequence`	Taper angles in degrees, following the same shape rules as `weights`. An angle of `45` corresponds to a weight of `1`. Mutually exclusive with `weights`.	`None`
`maximum_height`	`float`	The maximum extrusion height. If not provided, an inward slope is extruded up to the apex of the skeleton. A maximum height is required for outward or vertical slopes (weights that are negative, or angles of 90 degrees or more).	`None`

Returns:

Type	Description
tuple[:class:`compas.datastructures.Mesh`, list[:class:`compas.geometry.Line`]]	The triangulated, closed roof mesh (ready to display with hidden edges), and the roof outline as a list of line segments (eaves, hips and ridges).

Raises:

Type	Description
`ValueError`	If both `weights` and `angles` are provided. If the normal of the polygon is not directed vertically upwards like [0, 0, 1]. If the normal of a hole is not directed vertically downwards like [0, 0, -1].
`RuntimeError`	If CGAL fails to extrude the skeleton.

graph_from_skeleton_data ¤

graph_from_skeleton_data(
    points: VerticesNumpy, indices: IntNx1, edges: IntNx2, edge_types: IntNx1
) -> Graph

Create a graph from the skeleton data.

Parameters:

Name	Type	Description	Default
`points`	`VerticesNumpy`	The vertices of the skeleton, each vertex defined by 3 spatial coordinates.	required
`indices`	`IntNx1`	The vertex indices of the skeleton, corresponding to the points.	required
`edges`	`IntNx2`	The edges of the skeleton, each edge defined by 2 vertex indices.	required
`edge_types`	`IntNx1`	The type per edge, `0` for inner bisector, `1` for bisector, and `2` for boundary.	required

Returns:

Type	Description
`Graph`	The skeleton as a graph.

interior_straight_skeleton ¤

interior_straight_skeleton(
    points, as_graph=True
) -> Graph | tuple[VerticesNumpy, IntNx1, IntNx2, IntNx1]

Compute the skeleton of a 2D polygon.

Parameters:

Name	Type	Description	Default
`points`		The points of the polygon.	required
`as_graph`		Whether the skeleton should be returned as a graph, defaults to `True`.	`True`

Returns:

Type	Description
`Graph \| tuple[VerticesNumpy, IntNx1, IntNx2, IntNx1]`	The skeleton of the polygon.

Raises:

Type	Description
`ValueError`	If the normal of the polygon is not directed vertically upwards like [0, 0, 1].

interior_straight_skeleton_with_holes ¤

interior_straight_skeleton_with_holes(
    points, holes, as_graph=True
) -> Graph | tuple[VerticesNumpy, IntNx1, IntNx2, IntNx1]

Compute the skeleton of a 2D polygon with holes.

Parameters:

Name	Description	Default
`points`	The points of the 2D polygon.	required
`holes`	The holes of the polygon.	required
`as_graph`	Whether the skeleton should be returned as a graph, defaults to `True`.	`True`

Returns:

Type	Description
`Graph \| tuple[VerticesNumpy, IntNx1, IntNx2, IntNx1]`	The skeleton of the polygon.

Raises:

Type	Description
`ValueError`	If the normal of the polygon is not directed vertically upwards like [0, 0, 1]. If the normal of a hole is not directed vertically downwards like [0, 0, -1].

offset_polygon ¤

offset_polygon(points, offset) -> list[Polygon]

Compute the offset from a 2D polygon.

Parameters:

Name	Type	Description	Default
`points`		The points of the 2D polygon.	required
`offset`		The offset distance. If negative, the offset is outside the polygon, otherwise inside.	required

Returns:

Type	Description
`list[Polygon]`	The offset polygon(s).

Raises:

Type	Description
`ValueError`	If the normal of the polygon is not directed vertically upwards like [0, 0, 1].

offset_polygon_with_holes ¤

offset_polygon_with_holes(points, holes, offset) -> list[tuple[Polygon, list[Polygon]]]

Compute the offset from a 2D polygon with holes.

Parameters:

Name	Description	Default
`points`	The points of the 2D polygon.	required
`holes`	The holes of the polygon.	required
`offset`	The offset distance. If negative, the offset is outside the polygon, otherwise inside.	required

Returns:

Type	Description
`list[tuple[Polygon, list[Polygon]]]`	The polygons with holes.

Raises:

Type	Description
`ValueError`	If the normal of the polygon is not directed vertically upwards like [0, 0, 1]. If the normal of a hole is not directed vertically downwards like [0, 0, -1].

weighted_offset_polygon ¤

weighted_offset_polygon(points, offset, weights) -> list[Polygon]

Compute the offset from a 2D polygon with weights.

Parameters:

Name	Description	Default
`points`	The points of the 2D polygon.	required
`offset`	The offset distance. If negative, the offset is outside the polygon, otherwise inside.	required
`weights`	The weights for each edge, starting with the edge between the last and the first point.	required

Returns:

Type	Description
`list[Polygon]`	The offset polygon(s).

Raises:

Type	Description
`ValueError`	If the normal of the polygon is not directed vertically upwards like [0, 0, 1].
`ValueError`	If the number of weights does not match the number of points.