Unity Bounding Volume Heirachy

Dynamic Unity 3d BVH - 3d Bounding Volume Hierarchy.

Modified from David Jeske's SimpleScene

About

This is a 3d Bounding Volume Hiearchy implementation for Unity in C#. It is used for sorting objects that occupy volume and answering geometric queries about them; such as ray, box, and sphere intersection.

It includes an efficient algorithm for incrementally re-optimizing the BVH when contained objects move. This variation works in Unity and supports GameObjects.

For more information about what a BVH is, and about how to use this code, see David's CodeProject article:

• Dynamic Bounding Volume Hierarchy in C#

BVH.cs	The root interface to the BVH. Call RenderDebug() to render the debug bounds using DrawMeshInstanced.
BVHNode.cs	The code for managing, traversing, and optimizing the BVH
BVHGameObjectAdaptor.cs	A IBVHNodeAdaptor with GameObject integration.
BVHSphereAdaptor.cs	An example IBVHNodeAdaptor for spheres in the BVH.
IBVHNodeAdaptor.cs	Base interface for any BVHNodeAdaptor. Implement this to create a new adaptor.

Notable Modifications

• Supports GameObjects through a custom implementation of IBVHNodeAdapter (BVHGameObjectAdapter). Uses child renderers bounds to calculate bounds. Could be easily swapped out for any other bounds calculation. See BVHGameObjectAdaptor.GetBounds.
• BVHHelper provides a radial node traversal test to be used with Traverse().
• Code has been refactored to be closer to the .NET naming conventions.
• Includes some tests that can be used as a starting reference.

References

• "Fast, Effective BVH Updates for Animated Scenes" (Kopta, Ize, Spjut, Brunvand, David, Kensler)
• Space Partitioning: Octree vs. BVH
• Dynamic Bounding Volume Hiearchy in C#
• SimpleScene