💿🐜 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.
187 lines
5.5 KiB
187 lines
5.5 KiB
/*
|
|
* Copyright (C) 2021 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 "mesh-functions.hpp"
|
|
#include "math/math.hpp"
|
|
#include <unordered_map>
|
|
|
|
namespace geom {
|
|
|
|
struct edge_hasher
|
|
{
|
|
std::size_t operator()(const std::array<std::size_t, 2>& v) const noexcept
|
|
{
|
|
std::size_t hash = std::hash<std::size_t>()(v[0]);
|
|
return hash ^ (std::hash<std::size_t>()(v[1]) + 0x9e3779b9 + (hash << 6) + (hash >> 2));
|
|
}
|
|
};
|
|
|
|
void create_triangle_mesh(mesh& mesh, const std::vector<float3>& vertices, const std::vector<std::array<std::uint_fast32_t, 3>>& triangles)
|
|
{
|
|
for (const auto& vertex: vertices)
|
|
mesh.add_vertex(vertex);
|
|
|
|
std::unordered_map<std::array<std::size_t, 2>, geom::mesh::edge*, edge_hasher> edge_map;
|
|
const std::vector<mesh::vertex*>& mesh_vertices = mesh.get_vertices();
|
|
std::vector<geom::mesh::edge*> loop(3);
|
|
|
|
for (const auto& triangle: triangles)
|
|
{
|
|
geom::mesh::vertex* triangle_vertices[3] =
|
|
{
|
|
mesh_vertices[triangle[0]],
|
|
mesh_vertices[triangle[1]],
|
|
mesh_vertices[triangle[2]]
|
|
};
|
|
|
|
for (int j = 0; j < 3; ++j)
|
|
{
|
|
geom::mesh::vertex* start = triangle_vertices[j];
|
|
geom::mesh::vertex* end = triangle_vertices[(j + 1) % 3];
|
|
|
|
if (auto it = edge_map.find({start->index, end->index}); it != edge_map.end())
|
|
{
|
|
loop[j] = it->second;
|
|
}
|
|
else
|
|
{
|
|
loop[j] = mesh.add_edge(start, end);
|
|
edge_map[{start->index, end->index}] = loop[j];
|
|
edge_map[{end->index, start->index}] = loop[j]->symmetric;
|
|
}
|
|
|
|
}
|
|
|
|
mesh.add_face(loop);
|
|
}
|
|
}
|
|
|
|
void calculate_face_normals(float3* normals, const mesh& mesh)
|
|
{
|
|
const std::vector<mesh::face*>& faces = mesh.get_faces();
|
|
|
|
for (std::size_t i = 0; i < faces.size(); ++i)
|
|
{
|
|
const mesh::face& face = *(faces[i]);
|
|
const float3& a = face.edge->vertex->position;
|
|
const float3& b = face.edge->next->vertex->position;
|
|
const float3& c = face.edge->previous->vertex->position;
|
|
|
|
normals[i] = math::normalize(math::cross(b - a, c - a));
|
|
}
|
|
}
|
|
|
|
float3 calculate_face_normal(const mesh::face& face)
|
|
{
|
|
const float3& a = face.edge->vertex->position;
|
|
const float3& b = face.edge->next->vertex->position;
|
|
const float3& c = face.edge->previous->vertex->position;
|
|
return math::normalize(math::cross(b - a, c - a));
|
|
}
|
|
|
|
void calculate_vertex_tangents(float4* tangents, const float2* texcoords, const float3* normals, const mesh& mesh)
|
|
{
|
|
const std::vector<mesh::face*>& faces = mesh.get_faces();
|
|
const std::vector<mesh::vertex*>& vertices = mesh.get_vertices();
|
|
|
|
// Allocate tangent and bitangent buffers
|
|
float3* tangent_buffer = new float3[vertices.size()];
|
|
float3* bitangent_buffer = new float3[vertices.size()];
|
|
for (std::size_t i = 0; i < vertices.size(); ++i)
|
|
{
|
|
tangent_buffer[i] = {0.0f, 0.0f, 0.0f};
|
|
bitangent_buffer[i] = {0.0f, 0.0f, 0.0f};
|
|
}
|
|
|
|
// Accumulate tangents and bitangents
|
|
for (std::size_t i = 0; i < faces.size(); ++i)
|
|
{
|
|
const mesh::face& face = *(faces[i]);
|
|
std::size_t ia = face.edge->vertex->index;
|
|
std::size_t ib = face.edge->next->vertex->index;
|
|
std::size_t ic = face.edge->previous->vertex->index;
|
|
const float3& a = vertices[ia]->position;
|
|
const float3& b = vertices[ib]->position;
|
|
const float3& c = vertices[ic]->position;
|
|
const float2& uva = texcoords[ia];
|
|
const float2& uvb = texcoords[ib];
|
|
const float2& uvc = texcoords[ic];
|
|
|
|
float3 ba = b - a;
|
|
float3 ca = c - a;
|
|
float2 uvba = uvb - uva;
|
|
float2 uvca = uvc - uva;
|
|
|
|
float f = 1.0f / (uvba.x * uvca.y - uvca.x * uvba.y);
|
|
float3 tangent = (ba * uvca.y - ca * uvba.y) * f;
|
|
float3 bitangent = (ba * -uvca.x + ca * uvba.x) * f;
|
|
|
|
tangent_buffer[ia] += tangent;
|
|
tangent_buffer[ib] += tangent;
|
|
tangent_buffer[ic] += tangent;
|
|
bitangent_buffer[ia] += bitangent;
|
|
bitangent_buffer[ib] += bitangent;
|
|
bitangent_buffer[ic] += bitangent;
|
|
}
|
|
|
|
// Orthogonalize tangents
|
|
for (std::size_t i = 0; i < vertices.size(); ++i)
|
|
{
|
|
const float3& n = normals[i];
|
|
const float3& t = tangent_buffer[i];
|
|
const float3& b = bitangent_buffer[i];
|
|
|
|
// Gram-Schmidt orthogonalize tangent
|
|
float3 tangent = math::normalize(t - n * math::dot(n, t));
|
|
|
|
// Calculate bitangent sign
|
|
float bitangent_sign = (math::dot(math::cross(n, t), b) < 0.0f) ? -1.0f : 1.0f;
|
|
|
|
tangents[i] = {tangent.x, tangent.y, tangent.z, bitangent_sign};
|
|
}
|
|
|
|
// Free faceted tangents and bitangents
|
|
delete[] tangent_buffer;
|
|
delete[] bitangent_buffer;
|
|
}
|
|
|
|
aabb<float> calculate_bounds(const mesh& mesh)
|
|
{
|
|
float3 bounds_min;
|
|
float3 bounds_max;
|
|
for (int i = 0; i < 3; ++i)
|
|
{
|
|
bounds_min[i] = std::numeric_limits<float>::infinity();
|
|
bounds_max[i] = -std::numeric_limits<float>::infinity();
|
|
}
|
|
|
|
for (const mesh::vertex* vertex: mesh.get_vertices())
|
|
{
|
|
const auto& position = vertex->position;
|
|
for (int i = 0; i < 3; ++i)
|
|
{
|
|
bounds_min[i] = std::min<float>(bounds_min[i], position[i]);
|
|
bounds_max[i] = std::max<float>(bounds_max[i], position[i]);
|
|
}
|
|
}
|
|
|
|
return aabb<float>{bounds_min, bounds_max};
|
|
}
|
|
|
|
} // namespace geom
|