indigo.shared.trees

QuadTree is a data structure that allows you to store any value that exists in some space, e.g. a String at a Point or a class instance in a BoundingBox, e.g. The space station occupies a large BoundingCircle. The only restriction on what defines where something can be stored, is that it must have an implicit/given SpatialOps instance in scope.

You will also need an implicit QuadTree.InsertOptions in scope. You can use the defaults by doing given opts = QuadTree.DefaultOptions, however, the author's suspicion is that these are next to useless since the values are highly context specific. To make your own, do give opts = QuadTree.options(...) and fill in the blanks, considering carefully the size and nature of the data you plan to store. Try and set sensible limits to avoid degenerate cases of, for instance, very deep trees.

Remember, the point of a QuadTree is to make spatial search more efficient by allowing you to quickly cull areas that don't contain anything interesting.

Some points of interest about this implementation:

• It is valid for the same entry to exist in many parts of the tree. For example, if a LineSegment cuts across several quads, then all Quads it touches must contain that line segment's value at the leaf level.
• The 'insert' and 'search' functions should be effient since they can cull/ignore uninteresting nodes.
• The 'find' and the 'remove' functions are slower since they need to visit the whole tree to ensure all entries are removed.
• Leaf nodes are buckets that can (and will, probably) store more than one value at any given time, how many they should aim to store is configured in the options previously mentioned. The idea is to allow you to quickly find the value in the general area you care about cheaply, before you do some more expensive operation on them.

Holds the spatial location (e.g. a Vertex) and the value.