From 1d522c13e5922e9e7dc12ffc4ae11617548424d0 Mon Sep 17 00:00:00 2001
From: Pierre Krieger <pierre.krieger1708@gmail.com>
Date: Wed, 6 May 2015 10:38:15 +0200
Subject: [PATCH] Remove ToQuaternion

---
 src/matrix.rs     | 42 +++++++++++++++++++++---------------------
 src/quaternion.rs | 13 +------------
 src/rotation.rs   |  8 ++++----
 3 files changed, 26 insertions(+), 37 deletions(-)

diff --git a/src/matrix.rs b/src/matrix.rs
index 85bd3ac1..d683b73e 100644
--- a/src/matrix.rs
+++ b/src/matrix.rs
@@ -29,7 +29,7 @@ use approx::ApproxEq;
 use array::{Array1, Array2, FixedArray};
 use num::{BaseFloat, BaseNum};
 use point::{Point, Point3};
-use quaternion::{Quaternion, ToQuaternion};
+use quaternion::Quaternion;
 use vector::{Vector, EuclideanVector};
 use vector::{Vector2, Vector3, Vector4};
 
@@ -1358,44 +1358,44 @@ impl<S: BaseFloat> From<Matrix3<S>> for Matrix4<S> {
     }
 }
 
-impl<S: BaseFloat> ToQuaternion<S> for Matrix3<S> {
+impl<S: BaseFloat> From<Matrix3<S>> for Quaternion<S> {
     /// Convert the matrix to a quaternion
-    fn to_quaternion(&self) -> Quaternion<S> {
+    fn from(mat: Matrix3<S>) -> Quaternion<S> {
         // http://www.cs.ucr.edu/~vbz/resources/quatut.pdf
-        let trace = self.trace();
+        let trace = mat.trace();
         let half: S = cast(0.5f64).unwrap();
 
         if trace >= zero::<S>() {
             let s = (one::<S>() + trace).sqrt();
             let w = half * s;
             let s = half / s;
-            let x = (self[1][2] - self[2][1]) * s;
-            let y = (self[2][0] - self[0][2]) * s;
-            let z = (self[0][1] - self[1][0]) * s;
+            let x = (mat[1][2] - mat[2][1]) * s;
+            let y = (mat[2][0] - mat[0][2]) * s;
+            let z = (mat[0][1] - mat[1][0]) * s;
             Quaternion::new(w, x, y, z)
-        } else if (self[0][0] > self[1][1]) && (self[0][0] > self[2][2]) {
-            let s = (half + (self[0][0] - self[1][1] - self[2][2])).sqrt();
+        } else if (mat[0][0] > mat[1][1]) && (mat[0][0] > mat[2][2]) {
+            let s = (half + (mat[0][0] - mat[1][1] - mat[2][2])).sqrt();
             let w = half * s;
             let s = half / s;
-            let x = (self[0][1] - self[1][0]) * s;
-            let y = (self[2][0] - self[0][2]) * s;
-            let z = (self[1][2] - self[2][1]) * s;
+            let x = (mat[0][1] - mat[1][0]) * s;
+            let y = (mat[2][0] - mat[0][2]) * s;
+            let z = (mat[1][2] - mat[2][1]) * s;
             Quaternion::new(w, x, y, z)
-        } else if self[1][1] > self[2][2] {
-            let s = (half + (self[1][1] - self[0][0] - self[2][2])).sqrt();
+        } else if mat[1][1] > mat[2][2] {
+            let s = (half + (mat[1][1] - mat[0][0] - mat[2][2])).sqrt();
             let w = half * s;
             let s = half / s;
-            let x = (self[0][1] - self[1][0]) * s;
-            let y = (self[1][2] - self[2][1]) * s;
-            let z = (self[2][0] - self[0][2]) * s;
+            let x = (mat[0][1] - mat[1][0]) * s;
+            let y = (mat[1][2] - mat[2][1]) * s;
+            let z = (mat[2][0] - mat[0][2]) * s;
             Quaternion::new(w, x, y, z)
         } else {
-            let s = (half + (self[2][2] - self[0][0] - self[1][1])).sqrt();
+            let s = (half + (mat[2][2] - mat[0][0] - mat[1][1])).sqrt();
             let w = half * s;
             let s = half / s;
-            let x = (self[2][0] - self[0][2]) * s;
-            let y = (self[1][2] - self[2][1]) * s;
-            let z = (self[0][1] - self[1][0]) * s;
+            let x = (mat[2][0] - mat[0][2]) * s;
+            let y = (mat[1][2] - mat[2][1]) * s;
+            let z = (mat[0][1] - mat[1][0]) * s;
             Quaternion::new(w, x, y, z)
         }
     }
diff --git a/src/quaternion.rs b/src/quaternion.rs
index 46c0025c..03b3e1ac 100644
--- a/src/quaternion.rs
+++ b/src/quaternion.rs
@@ -37,12 +37,6 @@ use vector::{Vector3, Vector, EuclideanVector};
 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable)]
 pub struct Quaternion<S> { pub s: S, pub v: Vector3<S> }
 
-/// Represents types which can be expressed as a quaternion.
-pub trait ToQuaternion<S: BaseFloat> {
-    /// Convert this value to a quaternion.
-    fn to_quaternion(&self) -> Quaternion<S>;
-}
-
 impl<S: Copy + BaseFloat> Array1<S> for Quaternion<S> {
     #[inline]
     fn map<F>(&mut self, mut op: F) -> Quaternion<S> where F: FnMut(S) -> S {
@@ -387,18 +381,13 @@ impl<S: BaseFloat> From<Quaternion<S>> for Basis3<S> {
     fn from(quat: Quaternion<S>) -> Basis3<S> { Basis3::from_quaternion(&quat) }
 }
 
-impl<S: BaseFloat> ToQuaternion<S> for Quaternion<S> {
-    #[inline]
-    fn to_quaternion(&self) -> Quaternion<S> { self.clone() }
-}
-
 impl<S: BaseFloat + 'static> Rotation<S, Vector3<S>, Point3<S>> for Quaternion<S> {
     #[inline]
     fn identity() -> Quaternion<S> { Quaternion::identity() }
 
     #[inline]
     fn look_at(dir: &Vector3<S>, up: &Vector3<S>) -> Quaternion<S> {
-        Matrix3::look_at(dir, up).to_quaternion()
+        Matrix3::look_at(dir, up).into()
     }
 
     #[inline]
diff --git a/src/rotation.rs b/src/rotation.rs
index f9ad20fa..6c5419ab 100644
--- a/src/rotation.rs
+++ b/src/rotation.rs
@@ -20,7 +20,7 @@ use matrix::Matrix2;
 use matrix::Matrix3;
 use num::{BaseNum, BaseFloat};
 use point::{Point, Point2, Point3};
-use quaternion::{Quaternion, ToQuaternion};
+use quaternion::Quaternion;
 use ray::Ray;
 use vector::{Vector, Vector2, Vector3};
 
@@ -86,7 +86,7 @@ pub trait Rotation2<S>: Rotation<S, Vector2<S>, Point2<S>>
 pub trait Rotation3<S: BaseNum>: Rotation<S, Vector3<S>, Point3<S>>
                                + Into<Matrix3<S>>
                                + Into<Basis3<S>>
-                               + ToQuaternion<S>{
+                               + Into<Quaternion<S>> {
     /// Create a rotation using an angle around a given axis.
     fn from_axis_angle(axis: &Vector3<S>, angle: Rad<S>) -> Self;
 
@@ -255,9 +255,9 @@ impl<S: BaseFloat> From<Basis3<S>> for Matrix3<S> {
     fn from(b: Basis3<S>) -> Matrix3<S> { b.mat }
 }
 
-impl<S: BaseFloat + 'static> ToQuaternion<S> for Basis3<S> {
+impl<S: BaseFloat + 'static> From<Basis3<S>> for Quaternion<S> {
     #[inline]
-    fn to_quaternion(&self) -> Quaternion<S> { self.mat.to_quaternion() }
+    fn from(b: Basis3<S>) -> Quaternion<S> { b.mat.into() }
 }
 
 impl<S: BaseFloat + 'static> Rotation<S, Vector3<S>, Point3<S>> for Basis3<S> {