added transform_normal() to util/Transform

git-svn-id: svn://anubis/fart/trunk@34 7f9b0f55-74a9-4bce-be96-3c2cd072584d

util/Transform.cc

@@ -64,6 +64,11 @@ Vector Transform::transform_direction(Transform & t, const Vector & v)
     return t.getMatrix() % v;
 }
 
+Vector Transform::transform_normal(Transform & t, const Vector & v)
+{
+    return (t.getMatrix() % v).normalize();
+}
+
 Ray Transform::transform_ray(Transform & t, const Ray & r)
 {
     Vector newPosition = t.getMatrix() * r.getOrigin();

util/Transform.h

@@ -17,6 +17,7 @@ class Transform
         Matrix & getMatrix() { return m_matrix; }
         Vector transform_point(Transform & t, const Vector & v);
         Vector transform_direction(Transform & t, const Vector & v);
+        Vector transform_normal(Transform & t, const Vector & v);
         Ray transform_ray(Transform & t, const Ray & r);
 
     protected:

util/Vector.cc

@@ -17,7 +17,7 @@ Vector::Vector(double x, double y, double z)
     m_array[2] = z;
 }
 
-void Vector::normalize()
+Vector & Vector::normalize()
 {
     double length = sqrt(m_array[0] * m_array[0]
                        + m_array[1] * m_array[1]
@@ -25,6 +25,7 @@ void Vector::normalize()
     m_array[0] /= length;
     m_array[1] /= length;
     m_array[2] /= length;
+    return *this;
 }
 
 std::ostream & operator<<(std::ostream & out, const Vector & v)

util/Vector.h

@@ -11,7 +11,7 @@ class Vector
         Vector(double x, double y, double z);
         double & operator[](int idx) { return m_array[idx]; }
         double operator[](int idx) const { return m_array[idx]; }
-        void normalize();
+        Vector & normalize();
 
     private:
         double  m_array[3];