convex-hull.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_CONVEX_HULL_HPP
#define ANTKEEPER_GEOM_CONVEX_HULL_HPP
 
#include <engine/geom/bounding-volume.hpp>
#include <engine/geom/plane.hpp>
#include <engine/geom/sphere.hpp>
#include <engine/geom/aabb.hpp>
#include <cstddef>
#include <vector>
 
namespace geom {
 
template <class T>
struct convex_hull: public bounding_volume<T>
{
    std::vector<plane<T>> planes;
    
    explicit convex_hull(std::size_t size);
    
    convex_hull();
    
    virtual bounding_volume_type get_bounding_volume_type() const;
    virtual bool intersects(const sphere<T>& sphere) const;
    virtual bool intersects(const aabb<T>& aabb) const;
    virtual bool contains(const sphere<T>& sphere) const;
    virtual bool contains(const aabb<T>& aabb) const;
    virtual bool contains(const math::vector<T, 3>& point) const;
};
 
template <class T>
convex_hull<T>::convex_hull(std::size_t size):
    planes(size, plane<T>())
{}
 
template <class T>
convex_hull<T>::convex_hull()
{}
 
template <class T>
inline bounding_volume_type convex_hull<T>::get_bounding_volume_type() const
{
    return bounding_volume_type::convex_hull;
}
 
template <class T>
bool convex_hull<T>::intersects(const sphere<T>& sphere) const
{
    for (const plane<T>& plane: planes)
        if (plane.signed_distance(sphere.center) < -sphere.radius)
            return false;
    return true;
}
 
template <class T>
bool convex_hull<T>::intersects(const aabb<T>& aabb) const
{
    math::vector<T, 3> pv;
    for (const plane<T>& plane: planes)
    {   
        pv.x() = (plane.normal.x() > T(0)) ? aabb.max_point.x() : aabb.min_point.x();
        pv.y() = (plane.normal.y() > T(0)) ? aabb.max_point.y() : aabb.min_point.y();
        pv.z() = (plane.normal.z() > T(0)) ? aabb.max_point.z() : aabb.min_point.z();
        if (plane.signed_distance(pv) < T(0))
            return false;
    }
    
    return true;
}
 
template <class T>
bool convex_hull<T>::contains(const sphere<T>& sphere) const
{
    for (const plane<T>& plane: planes)
        if (plane.signed_distance(sphere.center) < sphere.radius)
            return false;
    return true;
}
 
template <class T>
bool convex_hull<T>::contains(const aabb<T>& aabb) const
{
    math::vector<T, 3> pv;
    math::vector<T, 3> nv;
    
    for (const plane<T>& plane: planes)
    {
        pv.x() = (plane.normal.x() > T(0)) ? aabb.max_point.x() : aabb.min_point.x();
        pv.y() = (plane.normal.y() > T(0)) ? aabb.max_point.y() : aabb.min_point.y();
        pv.z() = (plane.normal.z() > T(0)) ? aabb.max_point.z() : aabb.min_point.z();
        nv.x() = (plane.normal.x() < T(0)) ? aabb.max_point.x() : aabb.min_point.x();
        nv.y() = (plane.normal.y() < T(0)) ? aabb.max_point.y() : aabb.min_point.y();
        nv.z() = (plane.normal.z() < T(0)) ? aabb.max_point.z() : aabb.min_point.z();
        
        if (plane.signed_distance(pv) < T(0) || plane.signed_distance(nv) < T(0))
            return false;
    }
    
    return true;
}
 
template <class T>
bool convex_hull<T>::contains(const math::vector<T, 3>& point) const
{
    for (const plane<T>& plane: planes)
        if (plane.signed_distance(point) < T(0))
            return false;
 
    return true;
}
 
} // namespace geom
 
#endif // ANTKEEPER_GEOM_CONVEX_HULL_HPP