💿🐜 Antkeeper source code
https://antkeeper.com
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102 lines
2.9 KiB
102 lines
2.9 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 "geom/meshes/grid.hpp"
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#include <array>
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#include <cmath>
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#include <map>
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namespace geom {
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namespace meshes {
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geom::mesh* grid_xy(float length, std::size_t subdivisions_x, std::size_t subdivisions_y)
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{
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// Allocate new mesh
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geom::mesh* mesh = new geom::mesh();
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// Determine vertex count and placement
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std::size_t columns = subdivisions_x + 1;
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std::size_t rows = subdivisions_y + 1;
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float column_length = length / static_cast<float>(columns);
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float row_length = length / static_cast<float>(rows);
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// Generate mesh vertices
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float3 position;
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position.z = 0.0f;
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position.y = -length * 0.5f;
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for (std::size_t i = 0; i <= rows; ++i)
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{
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position.x = -length * 0.5f;
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for (std::size_t j = 0; j <= columns; ++j)
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{
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mesh->add_vertex(position);
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position.x += column_length;
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}
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position.y += row_length;
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}
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// Function to eliminate duplicate edges
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std::map<std::array<std::size_t, 2>, geom::mesh::edge*> edge_map;
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auto add_or_find_edge = [&](geom::mesh::vertex* start, geom::mesh::vertex* end) -> geom::mesh::edge*
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{
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geom::mesh::edge* edge;
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if (auto it = edge_map.find({start->index, end->index}); it != edge_map.end())
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{
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edge = it->second;
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}
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else
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{
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edge = mesh->add_edge(start, end);
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edge_map[{start->index, end->index}] = edge;
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edge_map[{end->index, start->index}] = edge->symmetric;
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}
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return edge;
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};
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// Connect vertices with edges and faces
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const std::vector<geom::mesh::vertex*>& vertices = mesh->get_vertices();
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for (std::size_t i = 0; i < rows; ++i)
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{
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for (std::size_t j = 0; j < columns; ++j)
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{
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geom::mesh::vertex* a = vertices[i * (columns + 1) + j];
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geom::mesh::vertex* b = vertices[(i + 1) * (columns + 1) + j];
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geom::mesh::vertex* c = vertices[i * (columns + 1) + j + 1];
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geom::mesh::vertex* d = vertices[(i + 1) * (columns + 1) + j + 1];
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// a---c
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// | |
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// b---d
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geom::mesh::edge* ab = add_or_find_edge(a, b);
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geom::mesh::edge* bd = add_or_find_edge(b, d);
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geom::mesh::edge* dc = add_or_find_edge(d, c);
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geom::mesh::edge* ca = add_or_find_edge(c, a);
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mesh->add_face({ab, bd, dc, ca});
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}
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}
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return mesh;
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}
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} // namespace meshes
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} // namespace geom
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