added ray tracer check for obb in line tracer

orange-cpp · orange-cpp · commit 6413c5d59cf0 · 2026-05-07T05:30:47.000+03:00
diff --git a/include/omath/collision/line_tracer.hpp b/include/omath/collision/line_tracer.hpp
@@ -4,6 +4,7 @@
 #pragma once
 
 #include "omath/3d_primitives/aabb.hpp"
+#include "omath/3d_primitives/obb.hpp"
 #include "omath/linear_algebra/triangle.hpp"
 #include "omath/linear_algebra/vector3.hpp"
 
@@ -36,6 +37,7 @@ namespace omath::collision
     {
         using TriangleType = Triangle<typename RayType::VectorType>;
         using AABBType = primitives::Aabb<typename RayType::VectorType::ContainedType>;
+        using OBBType = primitives::Obb<typename RayType::VectorType::ContainedType>;
 
     public:
         LineTracer() = delete;
@@ -137,6 +139,61 @@ namespace omath::collision
             return ray.start + dir * t_hit;
         }
 
+        // Slab method ray-OBB intersection. Project the ray into the OBB's local frame
+        // (axes are orthonormal, so the inverse rotation is just a transpose / dot products),
+        // then run the standard slab test against the local box [-half_extents, +half_extents].
+        // The ray parameter t is invariant under rigid transform, so the hit point is recovered
+        // in world space as ray.start + dir * t_hit.
+        [[nodiscard]]
+        constexpr static auto get_ray_hit_point(const RayType& ray, const OBBType& obb) noexcept
+        {
+            using T = typename RayType::VectorType::ContainedType;
+
+            const auto offset = ray.start - obb.center;
+            const auto dir = ray.direction_vector();
+
+            const T local_start[3] = {offset.dot(obb.axis_x), offset.dot(obb.axis_y), offset.dot(obb.axis_z)};
+            const T local_dir[3] = {dir.dot(obb.axis_x), dir.dot(obb.axis_y), dir.dot(obb.axis_z)};
+            const T half[3] = {obb.half_extents.x, obb.half_extents.y, obb.half_extents.z};
+
+            auto t_min = -std::numeric_limits<T>::infinity();
+            auto t_max = std::numeric_limits<T>::infinity();
+
+            const auto process_axis = [&](const T& d, const T& origin, const T& h) -> bool
+            {
+                constexpr T k_epsilon = std::numeric_limits<T>::epsilon();
+                if (std::abs(d) < k_epsilon)
+                    return origin >= -h && origin <= h;
+
+                const T inv = T(1) / d;
+                T t0 = (-h - origin) * inv;
+                T t1 = (h - origin) * inv;
+                if (t0 > t1)
+                    std::swap(t0, t1);
+
+                t_min = std::max(t_min, t0);
+                t_max = std::min(t_max, t1);
+                return t_min <= t_max;
+            };
+
+            if (!process_axis(local_dir[0], local_start[0], half[0]))
+                return ray.end;
+            if (!process_axis(local_dir[1], local_start[1], half[1]))
+                return ray.end;
+            if (!process_axis(local_dir[2], local_start[2], half[2]))
+                return ray.end;
+
+            const T t_hit = std::max(T(0), t_min);
+
+            if (t_max < T(0))
+                return ray.end; // box entirely behind origin
+
+            if (!ray.infinite_length && t_hit > T(1))
+                return ray.end; // box beyond ray endpoint
+
+            return ray.start + dir * t_hit;
+        }
+
         template<class MeshType>
         [[nodiscard]]
         constexpr static auto get_ray_hit_point(const RayType& ray, const MeshType& mesh) noexcept
diff --git a/tests/general/unit_test_line_tracer_obb.cpp b/tests/general/unit_test_line_tracer_obb.cpp
@@ -0,0 +1,225 @@
+//
+// Created by Vladislav on 07.05.2026.
+//
+#include "omath/3d_primitives/obb.hpp"
+#include "omath/collision/line_tracer.hpp"
+#include <cmath>
+#include <gtest/gtest.h>
+#include <numbers>
+
+using Vec3 = omath::Vector3<float>;
+using Ray = omath::collision::Ray<>;
+using LineTracer = omath::collision::LineTracer<>;
+using OBB = omath::primitives::Obb<float>;
+
+namespace
+{
+    Ray make_ray(const Vec3 start, const Vec3 end, const bool infinite = false)
+    {
+        Ray r;
+        r.start = start;
+        r.end = end;
+        r.infinite_length = infinite;
+        return r;
+    }
+
+    constexpr OBB axis_aligned_obb(const Vec3& center, const Vec3& half_extents) noexcept
+    {
+        return OBB{center, {1.f, 0.f, 0.f}, {0.f, 1.f, 0.f}, {0.f, 0.f, 1.f}, half_extents};
+    }
+
+    OBB rotated_around_z(const Vec3& center, const Vec3& half_extents, const float radians) noexcept
+    {
+        const auto c = std::cos(radians);
+        const auto s = std::sin(radians);
+        return OBB{center, {c, s, 0.f}, {-s, c, 0.f}, {0.f, 0.f, 1.f}, half_extents};
+    }
+} // namespace
+
+// --- axis-aligned OBB behaves like AABB ---
+
+TEST(LineTracerOBBTests, AxisAlignedHitAlongZ)
+{
+    const auto box = axis_aligned_obb({0.f, 0.f, 0.f}, {1.f, 1.f, 1.f});
+    const auto ray = make_ray({0.f, 0.f, -5.f}, {0.f, 0.f, 5.f});
+
+    const auto hit = LineTracer::get_ray_hit_point(ray, box);
+    EXPECT_NE(hit, ray.end);
+    EXPECT_NEAR(hit.x, 0.f, 1e-4f);
+    EXPECT_NEAR(hit.y, 0.f, 1e-4f);
+    EXPECT_NEAR(hit.z, -1.f, 1e-4f);
+}
+
+TEST(LineTracerOBBTests, AxisAlignedHitAlongX)
+{
+    const auto box = axis_aligned_obb({0.f, 0.f, 0.f}, {1.f, 1.f, 1.f});
+    const auto ray = make_ray({-5.f, 0.f, 0.f}, {5.f, 0.f, 0.f});
+
+    const auto hit = LineTracer::get_ray_hit_point(ray, box);
+    EXPECT_NE(hit, ray.end);
+    EXPECT_NEAR(hit.x, -1.f, 1e-4f);
+}
+
+TEST(LineTracerOBBTests, MissReturnsEnd)
+{
+    const auto box = axis_aligned_obb({0.f, 0.f, 0.f}, {1.f, 1.f, 1.f});
+    const auto ray = make_ray({0.f, 5.f, -5.f}, {0.f, 5.f, 5.f});
+
+    const auto hit = LineTracer::get_ray_hit_point(ray, box);
+    EXPECT_EQ(hit, ray.end);
+}
+
+TEST(LineTracerOBBTests, RayTooShortReturnsEnd)
+{
+    const auto box = axis_aligned_obb({4.f, 0.f, 0.f}, {1.f, 1.f, 1.f});
+    const auto ray = make_ray({0.f, 0.f, 0.f}, {2.f, 0.f, 0.f});
+
+    const auto hit = LineTracer::get_ray_hit_point(ray, box);
+    EXPECT_EQ(hit, ray.end);
+}
+
+TEST(LineTracerOBBTests, InfiniteRayHits)
+{
+    const auto box = axis_aligned_obb({4.f, 0.f, 0.f}, {1.f, 1.f, 1.f});
+    const auto ray = make_ray({0.f, 0.f, 0.f}, {2.f, 0.f, 0.f}, true);
+
+    const auto hit = LineTracer::get_ray_hit_point(ray, box);
+    EXPECT_NE(hit, ray.end);
+    EXPECT_NEAR(hit.x, 3.f, 1e-4f);
+}
+
+TEST(LineTracerOBBTests, RayStartsInsideBox)
+{
+    const auto box = axis_aligned_obb({0.f, 0.f, 0.f}, {1.f, 1.f, 1.f});
+    const auto ray = make_ray({0.f, 0.f, 0.f}, {5.f, 0.f, 0.f});
+
+    const auto hit = LineTracer::get_ray_hit_point(ray, box);
+    EXPECT_NE(hit, ray.end);
+    EXPECT_NEAR(hit.x, 0.f, 1e-4f);
+    EXPECT_NEAR(hit.y, 0.f, 1e-4f);
+    EXPECT_NEAR(hit.z, 0.f, 1e-4f);
+}
+
+TEST(LineTracerOBBTests, RayBehindBoxReturnsEnd)
+{
+    const auto box = axis_aligned_obb({4.f, 0.f, 0.f}, {1.f, 1.f, 1.f});
+    const auto ray = make_ray({10.f, 0.f, 0.f}, {20.f, 0.f, 0.f});
+
+    const auto hit = LineTracer::get_ray_hit_point(ray, box);
+    EXPECT_EQ(hit, ray.end);
+}
+
+// --- rotated OBB ---
+
+TEST(LineTracerOBBTests, RotatedBoxHitOnRotatedFace)
+{
+    // Box centred at the origin, rotated 45° around Z. After rotation, the box's "near" face
+    // (originally x=-1) is now perpendicular to the (1, 1, 0)/√2 direction. A ray approaching
+    // from +X (along world -X) first hits the box at the rotated face — at x = √2 ≈ 1.414.
+    const auto box = rotated_around_z({0.f, 0.f, 0.f}, {1.f, 1.f, 1.f}, std::numbers::pi_v<float> / 4.f);
+    const auto ray = make_ray({5.f, 0.f, 0.f}, {-5.f, 0.f, 0.f});
+
+    const auto hit = LineTracer::get_ray_hit_point(ray, box);
+    EXPECT_NE(hit, ray.end);
+    EXPECT_NEAR(hit.x, std::numbers::sqrt2_v<float>, 1e-4f);
+    EXPECT_NEAR(hit.y, 0.f, 1e-4f);
+    EXPECT_NEAR(hit.z, 0.f, 1e-4f);
+}
+
+TEST(LineTracerOBBTests, RotatedBoxMissesWhereAabbWouldHit)
+{
+    // A unit cube rotated 45° around Z has an XY footprint that is a diamond reaching
+    // (±√2, 0) and (0, ±√2). The AABB envelope spans x,y ∈ [-√2, √2], but at y just below √2
+    // the diamond is essentially a point. A ray at y = 1.43 is outside the diamond entirely
+    // (|x| + |y| ≤ √2 ⇒ |x| ≤ √2 - 1.43 < 0), yet it would still pass through the AABB
+    // envelope of the rotated box.
+    const auto box = rotated_around_z({0.f, 0.f, 0.f}, {1.f, 1.f, 1.f}, std::numbers::pi_v<float> / 4.f);
+    const auto ray = make_ray({-5.f, 1.43f, 0.f}, {5.f, 1.43f, 0.f});
+
+    const auto hit = LineTracer::get_ray_hit_point(ray, box);
+    EXPECT_EQ(hit, ray.end);
+}
+
+TEST(LineTracerOBBTests, RotatedThinBoxHitFromTheSide)
+{
+    // Long, thin axis-aligned slab along X, rotated 90° around Z so it now points along Y.
+    // A ray from +X straight back along -X must miss (the slab is thin in X), but a ray along
+    // -Y from +Y must hit.
+    const auto box = rotated_around_z({0.f, 0.f, 0.f}, {5.f, 0.5f, 1.f}, std::numbers::pi_v<float> / 2.f);
+
+    const auto ray_along_x = make_ray({10.f, 0.f, 0.f}, {-10.f, 0.f, 0.f});
+    const auto hit_x = LineTracer::get_ray_hit_point(ray_along_x, box);
+    EXPECT_NE(hit_x, ray_along_x.end);
+    EXPECT_NEAR(hit_x.x, 0.5f, 1e-4f); // hit on the rotated slab's narrow side
+
+    const auto ray_along_y = make_ray({0.f, 10.f, 0.f}, {0.f, -10.f, 0.f});
+    const auto hit_y = LineTracer::get_ray_hit_point(ray_along_y, box);
+    EXPECT_NE(hit_y, ray_along_y.end);
+    EXPECT_NEAR(hit_y.y, 5.f, 1e-4f); // hit on the long end at y=+5
+}
+
+TEST(LineTracerOBBTests, RotatedAndTranslatedBoxHit)
+{
+    const auto box = rotated_around_z({10.f, 5.f, 0.f}, {1.f, 1.f, 1.f}, std::numbers::pi_v<float> / 4.f);
+    // Ray approaches the rotated box from +X.
+    const auto ray = make_ray({20.f, 5.f, 0.f}, {0.f, 5.f, 0.f});
+
+    const auto hit = LineTracer::get_ray_hit_point(ray, box);
+    EXPECT_NE(hit, ray.end);
+    EXPECT_NEAR(hit.x, 10.f + std::numbers::sqrt2_v<float>, 1e-4f);
+    EXPECT_NEAR(hit.y, 5.f, 1e-4f);
+}
+
+TEST(LineTracerOBBTests, ParallelRayOutsideMisses)
+{
+    // Ray runs parallel to a slab face, completely outside the slab.
+    const auto box = axis_aligned_obb({0.f, 0.f, 0.f}, {1.f, 1.f, 1.f});
+    const auto ray = make_ray({-5.f, 2.f, 0.f}, {5.f, 2.f, 0.f});
+
+    const auto hit = LineTracer::get_ray_hit_point(ray, box);
+    EXPECT_EQ(hit, ray.end);
+}
+
+TEST(LineTracerOBBTests, ParallelRayInsideHits)
+{
+    // Ray runs parallel to a slab face but inside the slab — should still hit the entry plane.
+    const auto box = axis_aligned_obb({0.f, 0.f, 0.f}, {1.f, 1.f, 1.f});
+    const auto ray = make_ray({-5.f, 0.5f, 0.f}, {5.f, 0.5f, 0.f});
+
+    const auto hit = LineTracer::get_ray_hit_point(ray, box);
+    EXPECT_NE(hit, ray.end);
+    EXPECT_NEAR(hit.x, -1.f, 1e-4f);
+}
+
+TEST(LineTracerOBBTests, MatchesAabbForAxisAlignedBox)
+{
+    using AABB = omath::primitives::Aabb<float>;
+
+    struct
+    {
+        Vec3 center;
+        Vec3 half;
+        Vec3 ray_start;
+        Vec3 ray_end;
+    } cases[] = {
+            {{0.f, 0.f, 0.f}, {1.f, 1.f, 1.f}, {-5.f, 0.f, 0.f}, {5.f, 0.f, 0.f}},
+            {{0.f, 0.f, 0.f}, {1.f, 1.f, 1.f}, {0.f, -5.f, 0.f}, {0.f, 5.f, 0.f}},
+            {{4.f, 0.f, 0.f}, {1.f, 1.f, 1.f}, {0.f, 0.f, 0.f}, {2.f, 0.f, 0.f}}, // too short
+            {{0.f, 0.f, 0.f}, {1.f, 1.f, 1.f}, {-5.f, 5.f, 0.f}, {5.f, 5.f, 0.f}}, // miss
+            {{2.f, 3.f, -1.f}, {0.5f, 0.5f, 0.5f}, {0.f, 0.f, 0.f}, {10.f, 15.f, -5.f}}, // diagonal
+    };
+
+    for (const auto& [center, half, start, end]: cases)
+    {
+        const AABB aabb{center - half, center + half};
+        const auto obb = axis_aligned_obb(center, half);
+        const auto ray = make_ray(start, end);
+
+        const auto aabb_hit = LineTracer::get_ray_hit_point(ray, aabb);
+        const auto obb_hit = LineTracer::get_ray_hit_point(ray, obb);
+
+        EXPECT_NEAR(aabb_hit.x, obb_hit.x, 1e-4f);
+        EXPECT_NEAR(aabb_hit.y, obb_hit.y, 1e-4f);
+        EXPECT_NEAR(aabb_hit.z, obb_hit.z, 1e-4f);
+    }
+}
