/*
 * 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/>.
 */

#ifndef ANTKEEPER_GEOM_MESH_FUNCTIONS_HPP
#define ANTKEEPER_GEOM_MESH_FUNCTIONS_HPP

#include <engine/geom/primitives/box.hpp>
#include <engine/geom/mesh.hpp>
#include <engine/utility/fundamental-types.hpp>
#include <array>
#include <vector>

namespace geom {

/**
 * Creates a triangle mesh from a list of vertices and indices.
 *
 * @param[out] mesh Mesh to which vertices, edges, and faces will be added.
 * @param vertices Vertex positions
 * @param triangles Triangle indices
 * @return Newly created triangle mesh.
 */
void create_triangle_mesh(mesh& mesh, const std::vector<float3>& vertices, const std::vector<std::array<std::uint_fast32_t, 3>>& triangles);

/**
 * Calculates normals for each face.
 *
 * @param[out] Array in which faceted normals will be stored.
 */
void calculate_face_normals(float3* normals, const mesh& mesh);

float3 calculate_face_normal(const mesh::face& face);

/**
 * Calculates smooth tangents per-vertex.
 *
 * @param[out] tangents Array in which vertex tangents will be stored. A bitangent sign is stored in each tangent vector's fourth component.
 * @param[in] texcoords Array containing vertex texture coordinates.
 * @param[in] normals Array containing vertex normals.
 */
void calculate_vertex_tangents(float4* tangents, const float2* texcoords, const float3* normals, const mesh& mesh);

/**
 * Calculates the AABB bounds of a mesh.
 */
box<float> calculate_bounds(const mesh& mesh);

/**
 * Triangulates a face by adding a new vertex in the center, then creating triangles between the edges of the original face and the new vertex.
 *
 * @param mesh Mesh containing the face to poke.
 * @param index Index of the face to poke.
 * @return Pointer to the newly-created vertex in the center of the face, or `nullptr` if the face could not be poked.
 */
mesh::vertex* poke_face(mesh& mesh, std::size_t index);

} // namespace geom

#endif // ANTKEEPER_GEOM_MESH_FUNCTIONS_HPP