brep-face.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-face.hpp>
#include <engine/geom/brep/brep-mesh.hpp>
#include <algorithm>
#include <vector>
 
namespace geom {
 
void brep_face_loop_list::push_back(brep_loop* loop)
{
    if (empty())
    {
        // List empty, initialize
        m_head = loop;
        loop->m_face_next = loop;
        loop->m_face_previous = loop;
    }
    else
    {
        // Append loop
        loop->m_face_next = m_head;
        loop->m_face_previous = m_head->m_face_previous;
        m_head->m_face_previous->m_face_next = loop;
        m_head->m_face_previous = loop;
    }
    
    ++m_size;
}
 
void brep_face_loop_list::insert(brep_loop* next, brep_loop* loop)
{
    loop->m_face_next = next;
    loop->m_face_previous = next->m_face_previous;
    next->m_face_previous->m_face_next = loop;
    next->m_face_previous = loop;
    
    ++m_size;
}
 
void brep_face_loop_list::remove(brep_loop* loop)
{
    // Directly link next and previous loops
    loop->m_face_next->m_face_previous = loop->m_face_previous;
    loop->m_face_previous->m_face_next = loop->m_face_next;
    
    // If loop was the list head, update head
    if (m_head == loop)
    {
        m_head = loop->m_face_next;
    }
    
    --m_size;
}
 
brep_face* brep_face_container::emplace_back(const std::span<brep_vertex*> vertices)
{
    if (vertices.size() < 3)
    {
        return nullptr;
    }
    
    // Find or make edges
    std::vector<brep_edge*> edges(vertices.size());
    std::size_t i = vertices.size() - 1;
    for (std::size_t j = 0; j < vertices.size(); ++j)
    {
        edges[i] = m_mesh->edges().find(vertices[i], vertices[j]);
        if (!edges[i])
        {
            edges[i] = m_mesh->edges().emplace_back(vertices[i], vertices[j]);
        }
        
        i = j;
    }
    
    // Allocate face
    brep_face* face = brep_element_container<brep_face>::emplace_back();
    face->m_index = size() - 1;
    
    // Make face loops
    for (std::size_t i = 0; i < vertices.size(); ++i)
    {
        brep_loop* loop = m_mesh->loops().emplace_back();
        
        loop->m_vertex = vertices[i];
        loop->m_edge = edges[i];
        loop->m_face = face;
        
        // Append loop to its edge's list of loops
        loop->m_edge->m_loops.push_back(loop);
        
        // Append loop to its face's list of loops
        face->m_loops.push_back(loop);
    }
    
    return face;
};
 
void brep_face_container::erase(brep_face* face)
{
    brep_loop* loop = face->loops().front();
    do
    {
        // Remove loop from its edge's list of loops
        loop->m_edge->m_loops.remove(loop);
        
        brep_loop* next_loop = loop->m_face_next;
        
        // Erase loop
        m_mesh->loops().erase(loop);
        
        loop = next_loop;
    }
    while (loop != face->loops().front());
    
    // Erase face
    brep_element_container<brep_face>::erase(face);
}
 
void brep_face_container::clear() noexcept
{
    while (!empty())
    {
        erase(back());
    }
}
 
void brep_face_container::reverse(brep_face* face)
{
    for (brep_loop* loop: face->loops())
    {
        // Swap order of loop vertices
        loop->m_vertex = loop->edge()->vertices()[loop->edge()->vertices()[0] == loop->vertex()];
        
        // Swap pointers to next and previous face loops
        std::swap(loop->m_face_next, loop->m_face_previous);
    }
}
 
} // namespace geom