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110 lines
3.4 KiB
C++
110 lines
3.4 KiB
C++
//
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// Created by Orange on 11/13/2024.
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//
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#pragma once
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#include "omath/linear_algebra/triangle.hpp"
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#include "omath/linear_algebra/vector3.hpp"
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namespace omath::collision
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{
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template<class T = Vector3<float>>
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class Ray final
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{
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public:
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using VectorType = T;
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VectorType start;
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VectorType end;
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bool infinite_length = false;
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[[nodiscard]]
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constexpr VectorType direction_vector() const noexcept
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{
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return end - start;
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}
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[[nodiscard]]
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constexpr VectorType direction_vector_normalized() const noexcept
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{
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return direction_vector().normalized();
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}
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};
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template<class RayType = Ray<>>
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class LineTracer final
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{
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using TriangleType = Triangle<typename RayType::VectorType>;
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public:
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LineTracer() = delete;
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[[nodiscard]]
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constexpr static bool can_trace_line(const RayType& ray, const TriangleType& triangle) noexcept
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{
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return get_ray_hit_point(ray, triangle) == ray.end;
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}
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// Realization of Möller–Trumbore intersection algorithm
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// https://en.wikipedia.org/wiki/M%C3%B6ller%E2%80%93Trumbore_intersection_algorithm
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[[nodiscard]]
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constexpr static auto get_ray_hit_point(const RayType& ray, const TriangleType& triangle) noexcept
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{
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constexpr float k_epsilon = std::numeric_limits<float>::epsilon();
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const auto side_a = triangle.side_a_vector();
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const auto side_b = triangle.side_b_vector();
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const auto ray_dir = ray.direction_vector();
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const auto p = ray_dir.cross(side_b);
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const auto det = side_a.dot(p);
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if (std::abs(det) < k_epsilon)
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return ray.end;
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const auto inv_det = 1 / det;
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const auto t = ray.start - triangle.m_vertex2;
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const auto u = t.dot(p) * inv_det;
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if ((u < 0 && std::abs(u) > k_epsilon) || (u > 1 && std::abs(u - 1) > k_epsilon))
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return ray.end;
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const auto q = t.cross(side_a);
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// ReSharper disable once CppTooWideScopeInitStatement
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const auto v = ray_dir.dot(q) * inv_det;
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if ((v < 0 && std::abs(v) > k_epsilon) || (u + v > 1 && std::abs(u + v - 1) > k_epsilon))
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return ray.end;
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const auto t_hit = side_b.dot(q) * inv_det;
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if (ray.infinite_length && t_hit <= k_epsilon)
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return ray.end;
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if (t_hit <= k_epsilon || t_hit > 1 - k_epsilon)
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return ray.end;
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return ray.start + ray_dir * t_hit;
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}
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template<class MeshType>
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[[nodiscard]]
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static auto get_ray_hit_point(const RayType& ray, const MeshType& mesh) noexcept
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{
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auto mesh_hit = ray.end;
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const auto begin = mesh.m_element_buffer_object.cbegin();
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const auto end = mesh.m_element_buffer_object.cend();
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for (auto current = begin; current < end; current = std::next(current))
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{
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const auto face = mesh.make_face_in_world_space(current);
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auto ray_stop_point = get_ray_hit_point(ray, face);
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if (ray_stop_point.distance_to(ray.start) < mesh_hit.distance_to(ray.start))
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mesh_hit = ray_stop_point;
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}
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return mesh_hit;
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}
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};
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} // namespace omath::collision
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