brep-edge.cpp

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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/>.
 */
 
#include <engine/geom/brep/brep-edge.hpp>
#include <engine/geom/brep/brep-mesh.hpp>
#include <algorithm>
 
namespace geom {
 
void brep_edge_loop_list::push_back(brep_loop* loop)
{
    if (empty())
    {
        // List empty, initialize
        m_head = loop;
        loop->m_edge_next = loop;
        loop->m_edge_previous = loop;
    }
    else
    {
        // Append loop
        loop->m_edge_next = m_head;
        loop->m_edge_previous = m_head->m_edge_previous;
        m_head->m_edge_previous->m_edge_next = loop;
        m_head->m_edge_previous = loop;
    }
    
    ++m_size;
}
 
void brep_edge_loop_list::remove(brep_loop* loop)
{
    // Directly link next and previous loops
    loop->m_edge_next->m_edge_previous = loop->m_edge_previous;
    loop->m_edge_previous->m_edge_next = loop->m_edge_next;
    
    // If loop was the list head, update head
    if (m_head == loop)
    {
        m_head = loop->m_edge_next;
    }
    
    --m_size;
}
 
brep_edge* brep_edge_container::emplace_back(brep_vertex* a, brep_vertex* b)
{
    if (a == b)
    {
        return nullptr;
    }
    
    brep_edge* ab = brep_element_container<brep_edge>::emplace_back();
    ab->m_index = size() - 1;
    ab->m_vertices[0] = a;
    ab->m_vertices[1] = b;
    
    // Append edge AB to the edge lists of vertices A and B
    a->m_edges.push_back(ab);
    b->m_edges.push_back(ab);
    
    return ab;
};
 
void brep_edge_container::erase(brep_edge* edge)
{
    // Kill all loops and faces bounded by this edge
    while (!edge->loops().empty())
    {
        m_mesh->faces().erase(edge->loops().back()->face());
    }
    
    // Remove this edge from its vertices' lists of edges
    edge->vertices().front()->m_edges.remove(edge);
    edge->vertices().back()->m_edges.remove(edge);
    
    // Erase edge
    brep_element_container<brep_edge>::erase(edge);
}
 
void brep_edge_container::clear() noexcept
{
    while (!empty())
    {
        erase(back());
    }
}
 
brep_edge* brep_edge_container::find(brep_vertex* a, brep_vertex* b) const
{
    if (!a->edges().empty() && !b->edges().empty() && a != b)
    {
        brep_edge* ea = a->edges().front();
        brep_edge* eb = b->edges().front();
        const std::size_t n = std::min<std::size_t>(a->edges().size(), b->edges().size());
        for (std::size_t i = 0; i < n; ++i)
        {
            if (ea->vertices()[1] == b || ea->vertices()[0] == b)
            {
                return ea;
            }
            
            if (eb->vertices()[1] == a || eb->vertices()[0] == a)
            {
                return eb;
            }
            
            ea = ea->m_vertex_next[ea->vertices()[1] == a];
            eb = eb->m_vertex_next[eb->vertices()[1] == b];
        }
    }
    
    return nullptr;
}
 
} // namespace geom