Voronoi 2D

PCGEx | Cluster : Voronoi 2D

Outputs a 2D Voronoi graph.

The Voronoi 2D node outputs a 2D Voronoi graph with options like balanced, canon, or centroid positioning. Adjust bounds, prune sites, and mark edges on the hull.

Points clouds that will be triangulated

Vtx

Endpoints of the output Edges

Edges

Edges associated with the output Vtxs

Sites

Updated & optionally pruned delaunay sites

Table of content

Properties

This node creates a 2D Voronoi diagram from the input points. If you’d like to know more about Voronoi intrinsic properties, check out the Wikipedia article!

details/diagrams/diagrams-voronoi-2d-lead.png

Properties

Property	Description
Settings
Method	Defines how the position of the Voronoi site is computed. See below for more infos.
Expand Bounds	Value added on each axis of the initial input points bounds, used for maths & processes involving bounds.
Prune Out of Bounds	Depending on the selected method, the diagram will produce out-of-bounds points (up to ±inf). Enabling this option lets you remove those points from the output.
Hull Attribute Name `Boolean`	If enabled, will flag output `Vtx` points that lie on the convex hull of the underlying Delaunay diagram. Note that this is not the exact hull, but rather an approximation.
Mark Edge on Touch	If enabled, edges that have at least a point on the Hull as marked as being on the hull; as opposed to only be marked as hull edges if both endpoints are on the hull.

Note that enabling Prune Out of Bounds points has a theorical risk of creating more than one finite cluster as a result.

Voronoi site position

details/diagrams/diagrams-voronoi-2d-sites.png

Mode
	Balanced Uses the centroid of the Delaunay site for the point that are outside the bounds, otherwise use circumcenters. Best of both worlds, or worst of both worlds; depending on how you look at it.
	Canon (Circumcenter) Uses the circumcenter of the Delaunay triangle. This is the true voronoi algorithm, it guarantees only convex sites.
	Centroid Uses the centroid of the Delaunay site. While more visually pleasing, some concave sites may appear depending on the initial topology.

Additional Outputs

It may come (very) handy to have access to updated and/or pruned output cell centroid. You can output an modified version of the In points, that better matches the output voronoi cells.

Settings
Output Sites	If enabled, the node will generate a new output. Sites output have matching ClusterId tags corresponding output Vtx data.
Prune Open Sites	If enabled, open (or incomplete) voronoi site will be pruned. This is especially useful if you intend to find individual & valid cell contours.
Open Site Flag `bool`	If the above is disabled, sites matching incomplete or open voronoi sites will be flagged with a boolean attribute.

Note that canon Voronoi sites are guaranteed to be convex; so if you’re using find contour, you can safely prune concave contours!

Projection Settings

The projection settings control how the point position is translated to a 2D space before the graph is computed; and how this projection will translate back to the original space, if relevant.

Property	Description
Projection Normal	Normal vector of the plane used for projection. By default, the projection plan normal is `Up`; so the graph is computed over the `X Y` plane.
Local Projection Normal	If enabled, uses a per-point projection vector.
Local Normal	Attribute ti read normal from,

Local projection normal is very powerful but can also be very clunky to use – it’s very easy to end up with singularities that will prevent the graph from being properly computed.

Cluster Output Settings

See Working with Clusters - Cluster Output Settings.