From cbde731b7407f55407f8b581be6d0e3cee6e74e0 Mon Sep 17 00:00:00 2001
From: Jason Travis Smith <Myrddin@CyberMagesLLC.com>
Date: Sat, 10 Dec 2016 16:09:09 -0500
Subject: [PATCH] Dot product is not a calculation of angle.

In my sleepy and sick state, I did not check on the actual return of
the dot product. As such, I relied on what I had remembered it being.
I had thought that it was the angle between two vectors, but this is
wrong and that is a separate formula that uses the dot product to
determine the angle in Euclidean space. So the change to Radians,
and all the messy extra type definitions, were unneeded. The only
operation that really needed the addition of the Radian type was the
angle operation.
---
 src/vector.rs | 54 ++++++++++++++++++---------------------------------
 1 file changed, 19 insertions(+), 35 deletions(-)

diff --git a/src/vector.rs b/src/vector.rs
index 0cd97b9..22b9b5e 100644
--- a/src/vector.rs
+++ b/src/vector.rs
@@ -268,11 +268,10 @@ pub trait Vector<T>: Debug + Display + Clone + Default + Zero + One
    ///
    /// let vector: Vector3<i32> = Vector3::<i32>::from_value(3i32);
    /// let vector_two: Vector3<i32> = Vector3::<i32>::from_value(3i32);
-   /// let dotProduct: Radian<f64> = vector.dot(&vector_two);
-   /// # assert_eq!(*dotProduct, 27f64);
+   /// let dotProduct: i64 = vector.dot(&vector_two);
+   /// # assert_eq!(dotProduct, 27i64);
    ///```
-   fn dot<R>(&self, vector: &Self) -> Radian<R>
-      where R: Real + ::std::convert::From<T>;
+   fn dot(&self, vector: &Self) -> T;
 }
 
 /// Defines the [EuclideanVector][1] trait.
@@ -292,14 +291,12 @@ pub trait EuclideanVector<T> : Vector<T> where T: Real
    ///```
    fn get_length(&self) -> T
    {
-      let sq_rt: T;
-      let length: Radian<T>;
+      let length: T;
 
-      length = self.dot(self);
-      sq_rt = (*length).sqrt();
-      assert!(sq_rt.is_finite());
+      length = self.dot(self).sqrt();
+      assert!(length.is_finite());
 
-      sq_rt
+      length
    }
 
    /// Get the squared length of the Vector.
@@ -314,10 +311,7 @@ pub trait EuclideanVector<T> : Vector<T> where T: Real
    ///```
    fn get_length_squared(&self) -> T
    {
-      let radians: Radian<T>;
-
-      radians = self.dot(self);
-      *radians
+      self.dot(self)
    }
 
    /// Normalizes the Vector by multplying all the
@@ -369,12 +363,9 @@ pub trait EuclideanVector<T> : Vector<T> where T: Real
    // TODO: Add an example here.
    fn is_perpendicular_to(&self, vector: &Self) -> bool
    {
-      let dot: T;
-
       // TODO: Make this work with a fudge factor since floats
       //       are tricky.
-      dot = *self.dot(vector);
-      dot == T::zero()
+      self.dot(vector) == T::zero()
    }
 
    /// Calculates the angle between this vector and
@@ -538,12 +529,9 @@ macro_rules! define_vector
             perform_method_on_components!(mul, {$(self.$field),+})
          }
 
-         fn dot<R>(&self, vector: &$structName<T>) -> Radian<R>
-            where R: Real + ::std::convert::From<T>
+         fn dot(&self, vector: &$structName<T>) -> T
          {
-            let dot: R;
-            dot = R::from(self.mul(vector).get_sum());
-            Radian::new(dot)
+            self.mul(vector).get_sum()
          }
       }
 
@@ -699,13 +687,9 @@ impl<T> Vector2<T> where T: Number
 
    /// Calculate the perpendicular dot product.
    // TODO: Add an example.
-   pub fn perpendicular_dot<R>(&self, vector: &Vector2<T>) -> Radian<R>
-      where R: Real + ::std::convert::From<T>
+   pub fn perpendicular_dot(&self, vector: &Vector2<T>) -> T
    {
-      let val: R;
-
-      val = R::from((self.x * vector.y) - (self.y * vector.x));
-      Radian::new(val)
+      (self.x * vector.y) - (self.y * vector.x)
    }
 
    /// Adds a z component with the given value to the Vector.
@@ -928,7 +912,8 @@ impl<T> EuclideanVector<T> for Vector2<T> where T: Real
 {
    fn angle(&self, vector: &Vector2<T>) -> Radian<T>
    {
-      Radian::atan2((*self.perpendicular_dot(vector)), (*self.dot(vector)))
+      // Shortcut.
+      Radian::atan2(self.perpendicular_dot(vector), self.dot(vector))
    }
 }
 
@@ -936,7 +921,8 @@ impl<T> EuclideanVector<T> for Vector3<T> where T: Real
 {
    fn angle(&self, vector: &Vector3<T>) -> Radian<T>
    {
-      Radian::atan2(self.cross(vector).get_length(), (*self.dot(vector)))
+      // Shortcut.
+      Radian::atan2(self.cross(vector).get_length(), self.dot(vector))
    }
 }
 
@@ -944,9 +930,7 @@ impl<T> EuclideanVector<T> for Vector4<T> where T: Real
 {
    fn angle(&self, vector: &Vector4<T>) -> Radian<T>
    {
-      let dot: T;
-
-      dot = *self.dot(vector);
-      Radian::acos(dot / self.get_length() * vector.get_length())
+      // The basic equation, this would work for any size Vector.
+      Radian::acos(self.dot(vector) / (self.get_length()*vector.get_length()))
    }
 }