# Crate bvh [−] [src]

A crate which exports rays, axis-aligned bounding boxes, and binary bounding volume hierarchies.

## About

This crate can be used for applications which contain intersection computations of rays
with primitives. For this purpose a binary tree BVH (Bounding Volume Hierarchy) is of great
use if the scene which the ray traverses contains a huge number of primitives. With a BVH the
intersection test complexity is reduced from O(n) to O(log2(n)) at the cost of building
the BVH once in advance. This technique is especially useful in ray/path tracers. For
use in a shader this module also exports a flattening procedure, which allows for
iterative traversal of the BVH.
This library is built on top of `nalgebra`

.

## Example

use bvh::aabb::{AABB, Bounded}; use bvh::bounding_hierarchy::{BoundingHierarchy, BHShape}; use bvh::bvh::BVH; use bvh::nalgebra::{Point3, Vector3}; use bvh::ray::Ray; let origin = Point3::new(0.0,0.0,0.0); let direction = Vector3::new(1.0,0.0,0.0); let ray = Ray::new(origin, direction); struct Sphere { position: Point3<f32>, radius: f32, node_index: usize, } impl Bounded for Sphere { fn aabb(&self) -> AABB { let half_size = Vector3::new(self.radius, self.radius, self.radius); let min = self.position - half_size; let max = self.position + half_size; AABB::with_bounds(min, max) } } impl BHShape for Sphere { fn set_bh_node_index(&mut self, index: usize) { self.node_index = index; } fn bh_node_index(&self) -> usize { self.node_index } } let mut spheres = Vec::new(); for i in 0..1000u32 { let position = Point3::new(i as f32, i as f32, i as f32); let radius = (i % 10) as f32 + 1.0; spheres.push(Sphere { position: position, radius: radius, node_index: 0, }); } let bvh = BVH::build(&mut spheres); let hit_sphere_aabbs = bvh.traverse(&ray, &spheres);

## Reexports

`pub extern crate nalgebra;` |

## Modules

aabb |
Axis Aligned Bounding Boxes. |

axis |
Axis enum for indexing three-dimensional structures. |

bounding_hierarchy |
This module defines the |

bvh |
This module defines a |

flat_bvh |
This module exports methods to flatten the |

ray |
This module defines a Ray structure and intersection algorithms for axis aligned bounding boxes and triangles. |

## Constants

EPSILON |
A minimal floating value used as a lower bound. TODO: replace by/add ULPS/relative float comparison methods. |