💿🐜 Antkeeper source code
https://antkeeper.com
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136 lines
3.5 KiB
136 lines
3.5 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/physics/kinematics/colliders/mesh-collider.hpp>
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#include <engine/debug/log.hpp>
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#include <engine/geom/intersection.hpp>
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#include <engine/geom/brep/brep-operations.hpp>
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#include <limits>
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namespace physics {
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mesh_collider::mesh_collider(std::shared_ptr<mesh_type> mesh)
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{
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set_mesh(mesh);
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}
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void mesh_collider::set_mesh(std::shared_ptr<mesh_type> mesh)
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{
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m_mesh = mesh;
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if (m_mesh)
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{
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// Store pointer to mesh vertex positions
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m_vertex_positions = &m_mesh->vertices().attributes().at<math::fvec3>("position");
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// If mesh has no face normals
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if (!m_mesh->faces().attributes().contains("normal"))
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{
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// Generate normals
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// generate_face_normals(*m_mesh);
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generate_vertex_normals(*m_mesh);
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}
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// Store pointer to mesh face normals
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m_face_normals = &m_mesh->faces().attributes().at<math::fvec3>("normal");
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}
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else
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{
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m_vertex_positions = nullptr;
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m_face_normals = nullptr;
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}
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rebuild_bvh();
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}
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void mesh_collider::rebuild_bvh()
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{
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if (m_mesh)
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{
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m_bvh.build(*m_mesh);
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}
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else
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{
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m_bvh.clear();
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}
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}
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std::optional<std::tuple<float, std::uint32_t, math::fvec3>> mesh_collider::intersection(const geom::ray<float, 3>& ray) const
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{
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if (!m_mesh)
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{
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return std::nullopt;
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}
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std::size_t box_hit_count = 0;
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std::size_t triangle_hit_count = 0;
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float nearest_face_distance = std::numeric_limits<float>::infinity();
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std::uint32_t nearest_face_index;
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// For each BVH leaf node that intersects ray
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m_bvh.visit
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(
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ray,
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[&](std::uint32_t index)
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{
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++box_hit_count;
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// If ray is facing backside of face
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if (math::dot((*m_face_normals)[index], ray.direction) > 0.0f)
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{
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// Ignore face
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return;
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}
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// Get pointer to mesh face from BVH primitive index
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geom::brep_face* face = m_mesh->faces()[index];
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// Get face vertex positions
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auto loop = face->loops().begin();
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const auto& a = (*m_vertex_positions)[loop->vertex()->index()];
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const auto& b = (*m_vertex_positions)[(++loop)->vertex()->index()];
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const auto& c = (*m_vertex_positions)[(++loop)->vertex()->index()];
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// If ray intersects face
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if (const auto intersection = geom::intersection(ray, a, b, c))
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{
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++triangle_hit_count;
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// If distance to point of intersection is nearer than nearest intersection
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float t = std::get<0>(*intersection);
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if (t < nearest_face_distance)
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{
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// Update nearest intersection
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nearest_face_distance = t;
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nearest_face_index = index;
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}
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}
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}
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);
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// debug::log::debug("mesh collider intersection test:\n\tboxes hit: {}\n\ttriangles hit: {}", box_hit_count, triangle_hit_count);
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if (!triangle_hit_count)
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{
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return std::nullopt;
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}
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return std::make_tuple(nearest_face_distance, nearest_face_index, (*m_face_normals)[nearest_face_index]);
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}
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} // namespace physics
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