Method BuildIndex

Namespace

GeometryHelper.Geometry

Assembly

GeometryHelper.dll

BuildIndex()

Builds a spatial index over the surface of this body, for asking it many questions.

public GeoBvh3 BuildIndex()

Returns

GeoBvh3

The hierarchy; it is a snapshot and holds no reference back to this shape.

Remarks

An index is worth building when the same shape is asked many questions. Building it costs a sort of the triangles, so it pays for itself over repeated queries and never on the first one; below a few dozen triangles the plain walk wins outright. Every shape here is immutable, so a tree stays valid for as long as the shape exists — build it once, keep it, throw it away with the shape.

It is Build and not Get because it does work. Calling it inside a loop is slower than not having it at all, which is exactly the mistake the name is there to prevent.

The index is over triangles and the body is not. GetIntersections on the tree reports one hit per triangle, so a ray landing on the diagonal two triangles share is named twice, while the body names each place once. Ask the body where you want places; ask the tree where you want speed and can keep clear of the edges — which is what Containment3 does by throwing its ray again in another direction when a hit lands near one.

BuildIndex(Tolerance)

Builds a spatial index over the surface of this body, within a tolerance.

public GeoBvh3 BuildIndex(Tolerance tolerance)

Parameters

tolerance Tolerance

The tolerance the triangulation works to.

Returns

GeoBvh3

The hierarchy; it is a snapshot and holds no reference back to this shape.