LBVH

This project is an implementation of an LBVH build algorithm, as described by Karras here.

One quality of LBVH trees is that they can be built very quickly. This makes them an ideal choice for real time ray tracing.

As a single header library, you can easily integrate this into a ray tracing project and speed up your BVH build times!

This project was inspired by the following other open source projects:

• Fast-BVH
• BVH
• visionaray

Usage

The only requirement the library imposes is that a class be defined which converts primitives to axis-aligned bounding boxes (AABBs). Here's the generally idea in C++ pseudocode.

#include <lbvh.h>

struct sphere final {
  float radius;
  float pos[3];
};

int main() {

  sphere spheres[3] {
    { 2, { 3,  5, 6 } },
    { 5, { 7, 10, 1 } },
    { 1, { 0,  1, 2 } }
  };

  auto sphere_to_box = [](const sphere& s) -> lbvh::aabb<float> {
    return lbvh::aabb<float> {
      // min
      {
        s.pos[0] - r,
        s.pos[1] - r,
        s.pos[2] - r
      },
      // max
      {
        s.pos[0] + r,
        s.pos[1] + r,
        s.pos[2] + r
      }
    };
  };

  lbvh::builder<float> builder;

  auto bvh = builder(spheres, 3, sphere_to_box);

  /* Handle BVH here */

  return 0;
}