💿🐜 Antkeeper source code
https://antkeeper.com
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335 lines
6.1 KiB
335 lines
6.1 KiB
/*
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* Copyright (C) 2021 Christopher J. Howard
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*
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* This file is part of Antkeeper source code.
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*
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* Antkeeper source code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Antkeeper source code is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "mesh.hpp"
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#include <stdexcept>
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namespace geom {
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mesh::~mesh()
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{
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// Deallocate vertices
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for (mesh::vertex* vertex: vertices)
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{
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delete vertex;
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}
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// Deallocate edges
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for (mesh::edge* edge: edges)
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{
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delete edge->symmetric;
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delete edge;
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}
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// Deallocate faces
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for (mesh::face* face: faces)
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{
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delete face;
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}
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}
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mesh::vertex* mesh::add_vertex(const float3& position)
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{
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mesh::vertex* vertex = new mesh::vertex();
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vertex->edge = nullptr;
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vertex->position = position;
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vertex->index = vertices.size();
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vertices.push_back(vertex);
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return vertex;
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}
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mesh::edge* mesh::add_edge(mesh::vertex* a, mesh::vertex* b)
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{
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mesh::edge* ab = new mesh::edge();
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mesh::edge* ba = new mesh::edge();
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ab->vertex = a;
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ab->face = nullptr;
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ab->previous = ba;
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ab->next = ba;
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ab->symmetric = ba;
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ab->index = edges.size();
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ba->vertex = b;
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ba->face = nullptr;
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ba->previous = ab;
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ba->next = ab;
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ba->symmetric = ab;
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ba->index = edges.size();
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if (!a->edge)
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{
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a->edge = ab;
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}
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else
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{
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mesh::edge* a_in = find_free_incident(a);
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mesh::edge* a_out = a_in->next;
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a_in->next = ab;
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ab->previous = a_in;
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ba->next = a_out;
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a_out->previous = ba;
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}
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if (!b->edge)
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{
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b->edge = ba;
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}
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else
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{
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mesh::edge* b_in = find_free_incident(b);
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mesh::edge* b_out = b_in->next;
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b_in->next = ba;
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ba->previous = b_in;
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ab->next = b_out;
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b_out->previous = ab;
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}
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// Add edge
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edges.push_back(ab);
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return ab;
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}
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mesh::face* mesh::add_face(const loop& loop)
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{
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if (loop.empty())
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{
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throw std::runtime_error("Empty edge loop");
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}
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// Validate edge loop
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for (std::size_t i = 0; i < loop.size(); ++i)
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{
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mesh::edge* current = loop[i];
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mesh::edge* next = loop[(i + 1) % loop.size()];
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if (current->symmetric->vertex != next->vertex)
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{
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// Disconnected edge loop
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throw std::runtime_error("Disconnected edge loop");
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}
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if (current->face)
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{
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// This edge already has a face
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throw std::runtime_error("Non-manifold mesh 1");
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}
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}
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// Make edges adjacent
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for (std::size_t i = 0; i < loop.size(); ++i)
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{
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if (!make_adjacent(loop[i], loop[(i + 1) % loop.size()]))
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{
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throw std::runtime_error("Non-manifold mesh 2");
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}
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}
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// Create face
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mesh::face* face = new mesh::face();
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face->edge = loop[0];
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face->index = faces.size();
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// Add face
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faces.push_back(face);
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// Connect edges to the face
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for (mesh::edge* edge: loop)
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{
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edge->face = face;
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}
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return face;
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}
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void mesh::remove_face(mesh::face* face)
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{
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// Nullify pointers to this face
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mesh::edge* edge = face->edge;
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do
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{
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edge->face = nullptr;
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edge = edge->next;
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}
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while (edge != face->edge);
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// Adjust indices of faces after this face
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for (std::size_t i = face->index + 1; i < faces.size(); ++i)
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{
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--faces[i]->index;
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}
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// Remove face from the faces vector
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faces.erase(faces.begin() + face->index);
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// Deallocate face
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delete face;
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}
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void mesh::remove_edge(mesh::edge* edge)
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{
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mesh::edge* ab = edge;
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mesh::edge* ba = edge->symmetric;
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mesh::vertex* a = ab->vertex;
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mesh::edge* a_in = ab->previous;
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mesh::edge* a_out = ba->next;
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mesh::vertex* b = ba->vertex;
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mesh::edge* b_in = ba->previous;
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mesh::edge* b_out = ab->next;
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// Remove dependent faces
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if (ab->face)
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remove_face(ab->face);
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if (ba->face)
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remove_face(ba->face);
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// Re-link edges
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if (a->edge == ab)
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a->edge = (a_out == ab) ? nullptr : a_out;
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if (b->edge == ba)
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b->edge = (b_out == ba) ? nullptr : b_out;
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a_in->next = a_out;
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a_out->previous = a_in;
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b_in->next = b_out;
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b_out->previous = b_in;
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// Adjust indices of edges after this edge
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for (std::size_t i = edge->index + 1; i < edges.size(); ++i)
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{
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--edges[i]->index;
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--edges[i]->symmetric->index;
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}
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// Remove edge from the edges vector
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edges.erase(edges.begin() + edge->index);
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// Deallocate edge
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delete edge->symmetric;
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delete edge;
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}
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void mesh::remove_vertex(mesh::vertex* vertex)
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{
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// Remove connected edges
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if (vertex->edge)
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{
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mesh::edge* current = nullptr;
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mesh::edge* next = vertex->edge;
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do
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{
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current = next;
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next = next->symmetric->next;
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if (next == current)
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{
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next = next->symmetric->next;
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}
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remove_edge(current);
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}
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while (current != next);
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}
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// Adjust indices of vertices after this vertex
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for (std::size_t i = vertex->index + 1; i < vertices.size(); ++i)
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{
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--vertices[i]->index;
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}
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// Remove vertex from the vertices vector
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vertices.erase(vertices.begin() + vertex->index);
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// Deallocate vertex
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delete vertex;
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}
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mesh::edge* mesh::find_free_incident(mesh::vertex* vertex) const
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{
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mesh::edge* begin = vertex->edge->symmetric;
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mesh::edge* current = begin;
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do
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{
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if (!current->face)
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{
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return current;
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}
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current = current->next->symmetric;
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}
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while (current != begin);
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return nullptr;
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}
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mesh::edge* mesh::find_free_incident(mesh::edge* start_edge, mesh::edge* end_edge) const
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{
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if (start_edge == end_edge)
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{
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return nullptr;
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}
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mesh::edge* current = start_edge;
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do
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{
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if (!current->face)
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{
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return current;
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}
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current = current->next->symmetric;
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}
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while (current != end_edge);
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return nullptr;
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}
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bool mesh::make_adjacent(mesh::edge* in, mesh::edge* out)
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{
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if (in->next == out)
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{
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return true;
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}
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mesh::edge* b = in->next;
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mesh::edge* d = out->previous;
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mesh::edge* g = find_free_incident(out->symmetric, in);
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if (!g)
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{
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return false;
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}
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mesh::edge* h = g->next;
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in->next = out;
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out->previous = in;
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g->next = b;
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b->previous = g;
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d->next = h;
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h->previous = d;
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return true;
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}
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} // namespace geom
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