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

@@ -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.proj(forward)).normalize();
-    Vector perpendicular_up = (up - up_projected_onto_forward).normalize();
     Vector right = forward * perpendicular_up;
     Matrix mult;
     mult[0][0] = right[0];

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] << "]";

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];