From 4e16f5d9bfa8b3761d931c4646a53bd757c84c63 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sat, 24 Jul 2021 12:00:54 +0300
Subject: [PATCH] Add ray-sphere intersection

---
 libs/geom/include/psemek/geom/intersection.hpp | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/libs/geom/include/psemek/geom/intersection.hpp b/libs/geom/include/psemek/geom/intersection.hpp
index f332dddc..dc8d8324 100644
--- a/libs/geom/include/psemek/geom/intersection.hpp
+++ b/libs/geom/include/psemek/geom/intersection.hpp
@@ -5,6 +5,7 @@
 #include <psemek/geom/simplex.hpp>
 #include <psemek/geom/ray.hpp>
 #include <psemek/geom/box.hpp>
+#include <psemek/geom/sphere.hpp>
 #include <psemek/geom/orientation.hpp>
 #include <psemek/geom/contains.hpp>
 #include <psemek/geom/gauss.hpp>
@@ -209,4 +210,18 @@ namespace psemek::geom
 		return static_cast<bool>(intersection(seg, s));
 	}
 
+	template <typename T, std::size_t N>
+	std::optional<std::pair<T, T>> intersection(ray<T, N> const & r, sphere<T, N> const & s)
+	{
+		auto d = r.origin - s.center;
+
+		return solve_quadratic(length_sqr(r.direction), T{2} * dot(r.direction, d), length_sqr(d) - sqr(s.radius));
+	}
+
+	template <typename T, std::size_t N, typename = std::enable_if_t<(N > 2)>>
+	bool intersect(ray<T, N> const & r, sphere<T, N> const & s)
+	{
+		return static_cast<bool>(intersection(r, s));
+	}
+
 }