💿🐜 Antkeeper source code
https://antkeeper.com
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
130 lines
3.5 KiB
130 lines
3.5 KiB
/*
|
|
* Copyright (C) 2020 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 "relief-map.hpp"
|
|
#include <array>
|
|
#include <cmath>
|
|
#include <map>
|
|
|
|
namespace cart
|
|
{
|
|
|
|
mesh* map_elevation(const std::function<float(float, float)>& function, float scale, std::size_t subdivisions)
|
|
{
|
|
// Allocate terrain mesh
|
|
mesh* mesh = new ::mesh();
|
|
|
|
// Determine vertex count and placement
|
|
std::size_t columns = static_cast<std::size_t>(std::pow(2, subdivisions));
|
|
std::size_t rows = columns;
|
|
float uv_scale = 1.0f / static_cast<float>(columns);
|
|
//std::size_t vertex_count = (columns + 1) * (rows + 1);
|
|
|
|
// Generate mesh vertices
|
|
float3 position;
|
|
float2 uv;
|
|
for (std::size_t i = 0; i <= rows; ++i)
|
|
{
|
|
uv.y = static_cast<float>(i) * uv_scale;
|
|
position.z = (uv.y - 0.5f) * scale;
|
|
|
|
for (std::size_t j = 0; j <= columns; ++j)
|
|
{
|
|
uv.x = static_cast<float>(j) * uv_scale;
|
|
|
|
position.x = (uv.x - 0.5f) * scale;
|
|
position.y = function(uv.x, uv.y);
|
|
|
|
mesh->add_vertex(position);
|
|
}
|
|
}
|
|
|
|
// Function to eliminate duplicate edges
|
|
std::map<std::array<std::size_t, 2>, mesh::edge*> edge_map;
|
|
auto add_or_find_edge = [&](mesh::vertex* start, mesh::vertex* end) -> mesh::edge*
|
|
{
|
|
mesh::edge* edge;
|
|
if (auto it = edge_map.find({start->index, end->index}); it != edge_map.end())
|
|
{
|
|
edge = it->second;
|
|
}
|
|
else
|
|
{
|
|
edge = mesh->add_edge(start, end);
|
|
edge_map[{start->index, end->index}] = edge;
|
|
edge_map[{end->index, start->index}] = edge->symmetric;
|
|
}
|
|
|
|
return edge;
|
|
};
|
|
|
|
// Connect vertices with edges and faces
|
|
const std::vector<mesh::vertex*>& vertices = mesh->get_vertices();
|
|
for (std::size_t i = 0; i < rows; ++i)
|
|
{
|
|
for (std::size_t j = 0; j < columns; ++j)
|
|
{
|
|
mesh::vertex* a = vertices[i * (columns + 1) + j];
|
|
mesh::vertex* b = vertices[(i + 1) * (columns + 1) + j];
|
|
mesh::vertex* c = vertices[i * (columns + 1) + j + 1];
|
|
mesh::vertex* d = vertices[(i + 1) * (columns + 1) + j + 1];
|
|
|
|
// +---+---+
|
|
// | \ | / |
|
|
// |---+---|
|
|
// | / | \ |
|
|
// +---+---+
|
|
if ((j % 2) == (i % 2))
|
|
{
|
|
mesh::edge* ab = add_or_find_edge(a, b);
|
|
mesh::edge* bd = add_or_find_edge(b, d);
|
|
mesh::edge* da = add_or_find_edge(d, a);
|
|
|
|
mesh::edge* ca = add_or_find_edge(c, a);
|
|
mesh::edge* ad = da->symmetric;
|
|
mesh::edge* dc = add_or_find_edge(d, c);
|
|
|
|
// a---c
|
|
// | \ |
|
|
// b---d
|
|
mesh->add_face({ab, bd, da});
|
|
mesh->add_face({ca, ad, dc});
|
|
}
|
|
else
|
|
{
|
|
mesh::edge* ab = add_or_find_edge(a, b);
|
|
mesh::edge* bc = add_or_find_edge(b, c);
|
|
mesh::edge* ca = add_or_find_edge(c, a);
|
|
mesh::edge* cb = bc->symmetric;
|
|
mesh::edge* bd = add_or_find_edge(b, d);
|
|
mesh::edge* dc = add_or_find_edge(d, c);
|
|
|
|
// a---c
|
|
// | / |
|
|
// b---d
|
|
mesh->add_face({ab, bc, ca});
|
|
mesh->add_face({cb, bd, dc});
|
|
}
|
|
}
|
|
}
|
|
|
|
return mesh;
|
|
}
|
|
|
|
} // namespace cart
|