bvh.hpp

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/*
 * Copyright (C) 2023  Christopher J. Howard
 *
 * This file is part of Antkeeper source code.
 *
 * Antkeeper source code is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Antkeeper source code is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Antkeeper source code.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef ANTKEEPER_GEOM_BVH_HPP
#define ANTKEEPER_GEOM_BVH_HPP
 
#include <engine/geom/primitives/ray.hpp>
#include <engine/geom/bvh/bvh-primitive.hpp>
#include <engine/geom/bvh/bvh-node.hpp>
#include <cstdint>
#include <functional>
#include <span>
#include <vector>
 
namespace geom {
 
class brep_mesh;
 
class bvh
{
public:
    using visitor_type = std::function<void(std::uint32_t)>;
    
    explicit bvh(std::span<const bvh_primitive> primitives);
    
    explicit bvh(const brep_mesh& mesh);
    
    constexpr bvh() noexcept = default;
    
    void build(std::span<const bvh_primitive> primitives);
    
    void build(const brep_mesh& mesh);
    
    void clear();
    
    inline void visit(const geom::ray<float, 3>& ray, const visitor_type& f) const
    {
        if (m_node_count)
        {
            visit(m_nodes.front(), ray, f);
        }
    }
    
    [[nodiscard]] inline constexpr const std::vector<bvh_node>& nodes() const noexcept
    {
        return m_nodes;
    }
    
private:
    void update_bounds(bvh_node& node, const std::span<const bvh_primitive>& primitives);
    
    void subdivide(bvh_node& node, const std::span<const bvh_primitive>& primitives);
    void visit(const bvh_node& node, const geom::ray<float, 3>& ray, const visitor_type& f) const;
    
    std::vector<std::uint32_t> m_primitive_indices;
    std::vector<bvh_node> m_nodes;
    std::uint32_t m_node_count{};
};
 
} // namespace geom
 
#endif // ANTKEEPER_GEOM_BVH_HPP