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Note: This is the 2nd version of this library. Check thev1 branch for the older, first versionof this library.

This library is a small, standalone library for BVH construction and traversal. It is licensedunder the MIT license.

(Scene by Blend Swap user MaTTeSr, availablehere,distributed under CC-BY 3.0)

Here is a comparison of this library with other alternatives(Embree,Fast-BVH, andnanort):

Here is a list of features supported by this library (changes fromv1 are indicated with [NEW]):

• [NEW] C++20 interface usingstd::span instead of raw pointers,
• Low-level API with direct access to various builders,
• [NEW] High-levelDefaultBuilder API which selects the best builder depending on the desiredBVH quality level.
• High-quality, single-threaded sweeping SAH builder,
• Fast, medium-quality, single-threaded binned SAH builder inspired by"On Fast Construction of SAH-based Bounding Volume Hierarchies", by I. Wald,
• Fast, high-quality, multithreaded mini-tree BVH builder inspired by"Rapid Bounding Volume Hierarchy Generation using Mini Trees", by P. Ganestam et al.,
• Reinsertion optimizer based on "Parallel Reinsertion for Bounding Volume HierarchyOptimization", by D. Meister and J. Bittner,
• Fast and robust traversal algorithm using "Robust BVH Ray Traversal", by T. Ize.
• Fast ray-triangle intersection algorithm based on"Fast, Minimum Storage Ray/Triangle Intersection", by T. Möller and B. Trumbore,
• [NEW] Surface area traversal order heuristic for shadow rays based on"SATO: Surface Area Traversal Order for Shadow Ray Tracing", by J. Nah and D. Manocha,
• Fast ray-sphere intersection routine,
• [NEW] Serialization/deserialization interface,
• [NEW] Variable amount of dimensions (e.g. 2D, 3D, 4D BVHs are supported) and different scalar types(e.g.float ordouble),
• [NEW] Only depends on the standard library (parallelization uses a custom thread pool based onstd::thread),
• [NEW] C API for the high-level parts of the library is available.

This library is header-only, and can be added as a CMake subproject by cloning or adding as thisrepository as submodule, for instance in<your-project>/contrib/bvh, and then adding this to<your-project>/CMakeLists.txt:

add_subdirectory(contrib/bvh)target_link_library(my_project PUBLIC bvh)

If you want to build the examples, use:

mkdir buildcd buildcmake .. -DCMAKE_BUILD_TYPE=<Debug|Release> -DENABLE_TESTING=ONcmake --build .

The library can be used via a small set of high-level C bindings. These bindings are not enabled bydefault, but can be built by configuring CMake with-DBVH_BUILD_C_API=ON. Additionally, if theintent is to use the library in a pure C environment which does not have the C++ standard library asa dependency, it might be a good idea to statically the C++ standard library. That can be done byadding the flag-DBVH_STATIC_LINK_STDLIB_C_API=ON to the CMake command line.

The library contains several examples that are kept up-to-date with the API:

• Abasic example that traces one ray on a scene made of a couple of triangles,
• Abenchmarking utility that showcases what the library can do.
• Aserialization test that shows how to save and load a BVH from a file.
• AC API example that shows how to use the C bindings to this library.