From 08a0047ba80c088c84bcbb0eff9ff5170c5eacf5 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop+git@gmail.com>
Date: Fri, 30 Jan 2009 00:18:20 +0000
Subject: [PATCH] added proj() and reflect() to util/Vector, changed
 util/Transform to use Vector::proj() in lookAt()

git-svn-id: svn://anubis/fart/trunk@66 7f9b0f55-74a9-4bce-be96-3c2cd072584d
---
 util/Transform.cc |  3 +--
 util/Vector.cc    | 14 ++++++++++++++
 util/Vector.h     |  2 ++
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/util/Transform.cc b/util/Transform.cc
index 514a4c7..c7853bc 100644
--- a/util/Transform.cc
+++ b/util/Transform.cc
@@ -19,8 +19,7 @@ void Transform::lookAt(const Vector & eye,
 {
     Vector forward = focus - eye;
     forward.normalize();
-    Vector up_projected_onto_forward = forward * (up % forward) / up.mag2();
-    Vector perpendicular_up = (up - up_projected_onto_forward).normalize();
+    Vector perpendicular_up = (up - up.proj(forward)).normalize();
     Vector right = forward * perpendicular_up;
     Matrix mult;
     mult[0][0] = right[0];
diff --git a/util/Vector.cc b/util/Vector.cc
index b2498a1..c19591d 100644
--- a/util/Vector.cc
+++ b/util/Vector.cc
@@ -40,6 +40,20 @@ double Vector::mag2() const
          + m_array[2] * m_array[2];
 }
 
+Vector Vector::proj(const Vector & target) const
+{
+    Vector target_normalized = target;
+    target_normalized.normalize();
+    return target_normalized * ((*this) % target_normalized);
+}
+
+Vector Vector::reflect(const Vector & target) const
+{
+    Vector projected = proj(target);
+    Vector me_to_proj = projected - (*this);
+    return projected + me_to_proj * 2.0;
+}
+
 std::ostream & operator<<(std::ostream & out, const Vector & v)
 {
     out << "[" << v[0] << ", " << v[1] << ", " << v[2] << "]";
diff --git a/util/Vector.h b/util/Vector.h
index 1a5f0cc..d290f35 100644
--- a/util/Vector.h
+++ b/util/Vector.h
@@ -14,6 +14,8 @@ class Vector
         Vector & normalize();
         double mag() const;
         double mag2() const;
+        Vector proj(const Vector & target) const;
+        Vector reflect(const Vector & target) const;
 
     private:
         double  m_array[3];