💿🐜 Antkeeper source code
https://antkeeper.com
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111 lines
3.6 KiB
111 lines
3.6 KiB
/*
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* Copyright (C) 2023 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 <engine/ai/navmesh.hpp>
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#include <engine/geom/closest-feature.hpp>
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#include <engine/geom/coordinates.hpp>
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#include <engine/math/quaternion.hpp>
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#include <iterator>
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namespace ai {
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navmesh_traversal traverse_navmesh(const geom::brep_mesh& mesh, geom::brep_face* face, geom::ray<float, 3> ray, float distance)
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{
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// Get vertex positions and face normals
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const auto& vertex_positions = mesh.vertices().attributes().at<math::fvec3>("position");
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const auto& face_normals = mesh.faces().attributes().at<math::fvec3>("normal");
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// Init traversal result
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navmesh_traversal traversal;
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traversal.edge = nullptr;
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// Save initial ray origin
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auto initial_origin = ray.origin;
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float segment_length = 0.0f;
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int edge_index;
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do
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{
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// Get triangle vertices
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auto loop_it = face->loops().begin();
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const auto& a = vertex_positions[loop_it->vertex()->index()];
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const auto& b = vertex_positions[(++loop_it)->vertex()->index()];
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const auto& c = vertex_positions[(++loop_it)->vertex()->index()];
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// Find closest feature on triangle to segment endpoint
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std::tie(traversal.barycentric, edge_index) = geom::closest_feature(a, b, c, ray.extrapolate(distance));
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// Convert barycentric coordinates of closest point to Cartesian coordinates
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traversal.cartesian = geom::barycentric_to_cartesian(traversal.barycentric, a, b, c);
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// Subtract length of projected segment from remaining distance
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segment_length = math::length(traversal.cartesian - ray.origin);
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distance -= segment_length;
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// Advance ray origin
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ray.origin = traversal.cartesian;
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// If no edge reached or no remaining distance, traversal is complete
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if (edge_index < 0 || distance <= 0.0f)
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{
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break;
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}
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// Find loop and edge on which the closest point lies
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auto closest_loop_it = face->loops().begin();
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std::advance(closest_loop_it, edge_index);
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geom::brep_loop* closest_loop = *closest_loop_it;
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geom::brep_edge* closest_edge = closest_loop->edge();
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// Abort if a boundary edge was reached
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if (closest_edge->loops().size() == 1)
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{
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traversal.edge = closest_edge;
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break;
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}
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// Find a loop and face that shares the closest edge
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auto symmetric_loop_it = closest_edge->loops().begin();
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if (*symmetric_loop_it == closest_loop)
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{
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++symmetric_loop_it;
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}
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geom::brep_loop* symmetric_loop = *symmetric_loop_it;
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geom::brep_face* symmetric_face = symmetric_loop->face();
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// Find quaternion representing rotation from normal of first face to normal of second face
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const auto& n0 = face_normals[face->index()];
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const auto& n1 = face_normals[symmetric_face->index()];
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const auto rotation = math::rotation(n0, n1);
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// Rotate ray direction
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ray.direction = rotation * ray.direction;
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// Move to next face
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face = symmetric_face;
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}
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while (segment_length > 0.0f);
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traversal.face = face;
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traversal.remaining_distance = distance;
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return traversal;
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}
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} // namespace ai
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