Add orx-interval-tree README.md

README.md

@@ -10,6 +10,7 @@ A growing library of assorted data structures, algorithms and utilities.
 - [`orx-file-watcher`](orx-file-watcher/README.md), `Program` extension method that allows monitoring and hot loading from files.
 - [`orx-filter-extension`](orx-filter-extension/README.md), `Program` extension method that provides Filter based `extend()`
 - [`orx-integral-image`](orx-integral-image/README.md), CPU-based and GPU-based implementation for integral images (summed area tables)
+- [`orx-interval-tree`](orx-interval-tree/README.md), datastructure for accelerating point-in-interval queries.
 - `orx-jumpflood`, a filter/shader based implementation of the jump flood algorithm for finding fast approximate (directional) distance fields
 - `orx-kdtree`, a kd-tree implementation for fast nearest point searches
 - [`orx-mesh-generators`](orx-mesh-generators/README.md), triangular mesh generators

orx-interval-tree/README.md

@@ -0,0 +1,24 @@
+# orx-interval-tree
+
+Interval trees intend to speed-up point in interval queries. Specifically in cases with a large set of items with a given
+fixed start and end time.
+
+For more information on interval trees read the [wikipedia page](https://en.wikipedia.org/wiki/Interval_tree).
+
+## Usage
+```
+// -- the item class we want to search for
+class Item(val start: Double, val end: Double)
+
+// -- the items we want to search in
+val items = List(100000) { Item(Math.random(), 1.0 + Math.random()) }
+
+// -- build the interval tree, note how buildIntervalTree accepts a function that returns the start and end of the interval.
+val tree = buildIntervalTree(items) {
+    Pair(it.start, it.end)
+}
+
+// -- search for all items that intersect 0.05
+val results = tree.queryPoint(0.05)
+```
+