From bc3eff9f961ab1d9dd39a3fc9c43ace59a2ea35c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ars=C3=A8ne=20P=C3=A9rard-Gayot?=
 <arsene.perard@laposte.net>
Date: Thu, 19 Aug 2021 13:07:11 +0200
Subject: [PATCH] Add option to eliminate dot product in sphere intersection,
 when the ray is known to be normalized

---
 include/bvh/sphere.hpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/bvh/sphere.hpp b/include/bvh/sphere.hpp
index ef609c86..bab1d669 100644
--- a/include/bvh/sphere.hpp
+++ b/include/bvh/sphere.hpp
@@ -37,9 +37,10 @@ struct Sphere  {
         return BoundingBox<Scalar>(origin - Vector3<Scalar>(radius), origin + Vector3<Scalar>(radius));
     }
 
+    template <bool AssumeNormalized = false>
     std::optional<Intersection> intersect(const Ray<Scalar>& ray) const {
         auto oc = ray.origin - origin;
-        auto a = dot(ray.direction, ray.direction);
+        auto a = AssumeNormalized ? Scalar(1) : dot(ray.direction, ray.direction);
         auto b = 2 * dot(ray.direction, oc);
         auto c = dot(oc, oc) - radius * radius;