Add a `ScalarMul` and a `ScalarDiv` trait.

Those might be useful to overcome rust limitations wrt operator overloading.

src/na.rs

@@ -33,6 +33,7 @@ pub use traits::{
     Rotate, Rotation, RotationMatrix, RotationWithTranslation,
     Row,
     ScalarAdd, ScalarSub,
+    ScalarMul, ScalarAdd,
     ToHomogeneous,
     Transform, Transformation,
     Translate, Translation,

src/traits/mod.rs

@@ -9,7 +9,7 @@ pub use self::structure::{FloatVec, FloatVecExt, Basis, Cast, Col, Dim, Indexabl
                           ColSlice, RowSlice, Eye};
 
 pub use self::operations::{Absolute, ApproxEq, Cov, Inv, LMul, Mean, Outer, PartialOrd, RMul,
-                           ScalarAdd, ScalarSub, Transpose};
+                           ScalarAdd, ScalarSub, ScalarMul, ScalarDiv, Transpose};
 pub use self::operations::{PartialOrdering, PartialLess, PartialEqual, PartialGreater, NotComparable};
 
 pub mod geometry;

src/traits/operations.rs

@@ -316,9 +316,7 @@ impl<N, T: Add<N, T>> ScalarAdd<N> for T {
     }
 }
 
-/**
- * Trait of objects having a subtraction with a scalar.
- */
+/// Trait of objects having a subtraction with a scalar.
 pub trait ScalarSub<N> {
     /// Gets the result of `self - n`.
     fn sub_s(&self, n: &N) -> Self;
@@ -330,3 +328,29 @@ impl<N, T: Sub<N, T>> ScalarSub<N> for T {
         *self - *n
     }
 }
+
+/// Trait of objects having a multiplication with a scalar.
+pub trait ScalarMul<N> {
+    /// Gets the result of `self * n`.
+    fn mul_s(&self, n: &N) -> Self;
+}
+
+impl<N, T: Mul<N, T>> ScalarMul<N> for T {
+    /// Gets the result of `self * n`.
+    fn mul_s(&self, n: &N) -> T {
+        *self * *n
+    }
+}
+
+/// Trait of objects having a division by a scalar.
+pub trait ScalarDiv<N> {
+    /// Gets the result of `self / n`.
+    fn div_s(&self, n: &N) -> Self;
+}
+
+impl<N, T: Div<N, T>> ScalarDiv<N> for T {
+    /// Gets the result of `self / n`.
+    fn div_s(&self, n: &N) -> T {
+        *self / *n
+    }
+}