From 1eee61002e14422af3c79ae0a37b27937e6af3d5 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop+git@gmail.com>
Date: Mon, 11 Oct 2010 15:21:50 +0000
Subject: [PATCH] reworked Vector::reflect() to reflect an INCOMING ray

git-svn-id: svn://anubis/fart/trunk@371 7f9b0f55-74a9-4bce-be96-3c2cd072584d
---
 main/Scene.cc |  4 ++--
 util/Vector.h | 10 +++++-----
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/main/Scene.cc b/main/Scene.cc
index deb3690..43afa9b 100644
--- a/main/Scene.cc
+++ b/main/Scene.cc
@@ -155,7 +155,7 @@ Color Scene::traceRayRecurse(const Ray & ray, int depth, double factor)
             {
                 color *= (1.0 - reflectance);
                 Vector reflected_direction =
-                    (-ray.getDirection()).reflect(hit.normal);
+                    ray.getDirection().reflect(hit.normal);
                 Ray newRay(hit.position, reflected_direction);
                 Vector jitter_surface_point = newRay[0.0001];
                 Ray jitterNewRay(jitter_surface_point, reflected_direction);
@@ -257,7 +257,7 @@ Color Scene::computePhong(const refptr<Material> material,
                 Vector directionToLight = jitterPosition - surfacePoint;
                 directionToLight.normalize();
                 Vector reflectedLightDirection =
-                    directionToLight.reflect(surfaceNormal);
+                    (-directionToLight).reflect(surfaceNormal);
 
                 Ray surfaceToLight(surfacePoint, directionToLight);
                 Color light_contribution =
diff --git a/util/Vector.h b/util/Vector.h
index 7fac54c..fe15fa8 100644
--- a/util/Vector.h
+++ b/util/Vector.h
@@ -60,9 +60,7 @@ class Vector
 
         Vector reflect(const Vector & target) const
         {
-            Vector projected = proj(target);
-            Vector me_to_proj = projected - (*this);
-            return (*this) + me_to_proj * 2.0;
+            return (*this) - target * (2 * dot(target));
         }
 
         Vector getPerpendicular() const
@@ -102,21 +100,23 @@ class Vector
         }
 
         /* Compute the dot-product of two vectors */
-        double operator%(const Vector & v2) const
+        double dot(const Vector & v2) const
         {
             return m_array[0] * v2.m_array[0]
                 + m_array[1] * v2.m_array[1]
                 + m_array[2] * v2.m_array[2];
         }
+        double operator%(const Vector & v2) const { return dot(v2); }
 
         /* Compute the cross-product of two vectors */
-        Vector operator*(const Vector & v2) const
+        Vector cross(const Vector & v2) const
         {
             return Vector(
                     m_array[1] * v2.m_array[2] - m_array[2] * v2.m_array[1],
                     m_array[2] * v2.m_array[0] - m_array[0] * v2.m_array[2],
                     m_array[0] * v2.m_array[1] - m_array[1] * v2.m_array[0]);
         }
+        Vector operator*(const Vector & v2) const { return cross(v2); }
 
         Vector operator+(const Vector & v2) const
         {