Add two traits: `CrossMatrix` and `Row`.

CrossMatrix is a trait for vectors having a cross product representable as a matrix.
Row is a trait for Matrixces and Vectors, to access (by index) their rows.

src/mat.rs

@@ -13,6 +13,7 @@ use traits::transformation::Transform;
 use traits::homogeneous::{FromHomogeneous, ToHomogeneous};
 use traits::indexable::Indexable;
 use traits::column::Column;
+use traits::row::Row;
 use traits::iterable::{Iterable, IterableMut};
 use traits::outer::Outer;
 use traits::scalar_op::{ScalarAdd, ScalarSub};
@@ -70,7 +71,8 @@ transform_impl!(Mat1, Vec1)
 // (specialized) inv_impl!(Mat1, 1)
 transpose_impl!(Mat1, 1)
 approx_eq_impl!(Mat1)
-column_impl!(Mat1, 1)
+column_impl!(Mat1, Vec1, 1)
+row_impl!(Mat1, Vec1, 1)
 to_homogeneous_impl!(Mat1, Mat2, 1, 2)
 from_homogeneous_impl!(Mat1, Mat2, 1, 2)
 outer_impl!(Vec1, Mat1)
@@ -111,7 +113,8 @@ transform_impl!(Mat2, Vec2)
 // (specialized) inv_impl!(Mat2, 2)
 transpose_impl!(Mat2, 2)
 approx_eq_impl!(Mat2)
-column_impl!(Mat2, 2)
+column_impl!(Mat2, Vec2, 2)
+row_impl!(Mat2, Vec2, 2)
 to_homogeneous_impl!(Mat2, Mat3, 2, 3)
 from_homogeneous_impl!(Mat2, Mat3, 2, 3)
 outer_impl!(Vec2, Mat2)
@@ -162,7 +165,8 @@ transform_impl!(Mat3, Vec3)
 // (specialized) inv_impl!(Mat3, 3)
 transpose_impl!(Mat3, 3)
 approx_eq_impl!(Mat3)
-column_impl!(Mat3, 3)
+column_impl!(Mat3, Vec3, 3)
+// (specialized) row_impl!(Mat3, Vec3, 3)
 to_homogeneous_impl!(Mat3, Mat4, 3, 4)
 from_homogeneous_impl!(Mat3, Mat4, 3, 4)
 outer_impl!(Vec3, Mat3)
@@ -239,7 +243,8 @@ transform_impl!(Mat4, Vec4)
 inv_impl!(Mat4, 4)
 transpose_impl!(Mat4, 4)
 approx_eq_impl!(Mat4)
-column_impl!(Mat4, 4)
+column_impl!(Mat4, Vec4, 4)
+row_impl!(Mat4, Vec4, 4)
 to_homogeneous_impl!(Mat4, Mat5, 4, 5)
 from_homogeneous_impl!(Mat4, Mat5, 4, 5)
 outer_impl!(Vec4, Mat4)
@@ -328,7 +333,8 @@ transform_impl!(Mat5, Vec5)
 inv_impl!(Mat5, 5)
 transpose_impl!(Mat5, 5)
 approx_eq_impl!(Mat5)
-column_impl!(Mat5, 5)
+column_impl!(Mat5, Vec5, 5)
+row_impl!(Mat5, Vec5, 5)
 to_homogeneous_impl!(Mat5, Mat6, 5, 6)
 from_homogeneous_impl!(Mat5, Mat6, 5, 6)
 outer_impl!(Vec5, Mat5)
@@ -427,5 +433,6 @@ transform_impl!(Mat6, Vec6)
 inv_impl!(Mat6, 6)
 transpose_impl!(Mat6, 6)
 approx_eq_impl!(Mat6)
-column_impl!(Mat6, 6)
+column_impl!(Mat6, Vec6, 6)
+row_impl!(Mat6, Vec6, 6)
 outer_impl!(Vec6, Mat6)

src/mat_macros.rs

@@ -183,28 +183,20 @@ macro_rules! indexable_impl(
 )
 
 macro_rules! column_impl(
-  ($t: ident, $dim: expr) => (
-    impl<N: Clone, V: Zero + Iterable<N> + IterableMut<N>> Column<V> for $t<N> {
+  ($t: ident, $tv: ident, $dim: expr) => (
+    impl<N: Clone + Zero> Column<$tv<N>> for $t<N> {
         #[inline]
-        fn set_column(&mut self, col: uint, v: V) {
+        fn set_column(&mut self, col: uint, v: $tv<N>) {
             for (i, e) in v.iter().enumerate() {
-                if i == Dim::dim::<$t<N>>() {
-                    break
-                }
-
                 self.set((i, col), e.clone());
             }
         }
 
         #[inline]
-        fn column(&self, col: uint) -> V {
-            let mut res = Zero::zero::<V>();
+        fn column(&self, col: uint) -> $tv<N> {
+            let mut res = Zero::zero::<$tv<N>>();
 
             for (i, e) in res.mut_iter().enumerate() {
-                if i >= Dim::dim::<$t<N>>() {
-                    break
-                }
-
                 *e = self.at((i, col));
             }
 
@@ -214,6 +206,30 @@ macro_rules! column_impl(
   )
 )
 
+macro_rules! row_impl(
+  ($t: ident, $tv: ident, $dim: expr) => (
+    impl<N: Clone + Zero> Row<$tv<N>> for $t<N> {
+        #[inline]
+        fn set_row(&mut self, row: uint, v: $tv<N>) {
+            for (i, e) in v.iter().enumerate() {
+                self.set((row, i), e.clone());
+            }
+        }
+
+        #[inline]
+        fn row(&self, row: uint) -> $tv<N> {
+            let mut res = Zero::zero::<$tv<N>>();
+
+            for (i, e) in res.mut_iter().enumerate() {
+                *e = self.at((row, i));
+            }
+
+            res
+        }
+    }
+  )
+)
+
 macro_rules! mul_impl(
   ($t: ident, $dim: expr) => (
     impl<N: Clone + Num> Mul<$t<N>, $t<N>> for $t<N> {

src/mat_spec.rs

@@ -1,6 +1,8 @@
 use std::num::{Zero, One};
+use vec::Vec3;
 use mat::{Mat1, Mat2, Mat3};
 use traits::inv::Inv;
+use traits::row::Row;
 
 // some specializations:
 impl<N: Num + Clone>
@@ -106,3 +108,38 @@ Inv for Mat3<N> {
         }
     }
 }
+
+impl<N: Clone> Row<Vec3<N>> for Mat3<N> {
+    #[inline]
+    fn row(&self, i: uint) -> Vec3<N> {
+        match i {
+            0 => Vec3::new(self.m11.clone(), self.m12.clone(), self.m13.clone()),
+            1 => Vec3::new(self.m21.clone(), self.m22.clone(), self.m23.clone()),
+            2 => Vec3::new(self.m31.clone(), self.m32.clone(), self.m33.clone()),
+            _ => fail!("Index out of range: 3d matrices do not have " + i.to_str() + " rows.")
+        }
+    }
+
+    #[inline]
+    fn set_row(&mut self, i: uint, r: Vec3<N>) {
+        match i {
+            0 => {
+                self.m11 = r.x.clone();
+                self.m12 = r.y.clone();
+                self.m13 = r.z;
+            },
+            1 => {
+                self.m21 = r.x.clone();
+                self.m22 = r.y.clone();
+                self.m23 = r.z;
+            },
+            2 => {
+                self.m31 = r.x.clone();
+                self.m32 = r.y.clone();
+                self.m33 = r.z;
+            },
+            _ => fail!("Index out of range: 3d matrices do not have " + i.to_str() + " rows.")
+
+        }
+    }
+}

src/nalgebra.rc

@@ -52,6 +52,7 @@ pub mod traits
     pub mod sample;
     pub mod indexable;
     pub mod column;
+    pub mod row;
     pub mod iterable;
     pub mod outer;
     pub mod cross;

src/traits/cross.rs

@@ -1,8 +1,16 @@
 /**
  * Trait of elements having a cross product.
  */
-pub trait Cross<Result>
-{
+pub trait Cross<V> {
     /// Computes the cross product between two elements (usually vectors).
-    fn cross(&self, other : &Self) -> Result;
+    fn cross(&self, other: &Self) -> V;
+}
+
+/**
+ * Trait of elements having a cross product operation which can be expressed as a matrix.
+ */
+pub trait CrossMatrix<M> {
+    /// The matrix associated to any cross product with this vector. I.e. `v.cross(anything)` =
+    /// `v.cross_matrix().rmul(anything)`.
+    fn cross_matrix(&self) -> M;
 }

src/traits/row.rs

@@ -0,0 +1,7 @@
+/// Traits to access rows of a matrix or vector.
+pub trait Row<R> {
+    /// Reads the `i`-th row of `self`.
+    fn row(&self, i: uint) -> R;
+    /// Writes the `i`-th row of `self`.
+    fn set_row(&mut self, i: uint, R);
+}

src/vec_spec.rs

@@ -1,10 +1,12 @@
 use std::num::{Zero, One};
 use traits::basis::Basis;
-use traits::cross::Cross;
+use traits::cross::{Cross, CrossMatrix};
 use traits::sample::UniformSphereSample;
 use traits::vec_cast::VecCast;
 use traits::vector::{AlgebraicVec};
+use traits::row::Row;
 use vec::{Vec1, Vec2, Vec3};
+use mat::Mat3;
 
 impl<N: Mul<N, N> + Sub<N, N>> Cross<Vec1<N>> for Vec2<N> {
     #[inline]
@@ -13,6 +15,14 @@ impl<N: Mul<N, N> + Sub<N, N>> Cross<Vec1<N>> for Vec2<N> {
     }
 }
 
+// FIXME: instead of returning a Vec2, define a Mat2x1 matrix?
+impl<N: Neg<N> + Clone> CrossMatrix<Vec2<N>> for Vec2<N> {
+    #[inline]
+    fn cross_matrix(&self) -> Vec2<N> {
+        Vec2::new(-self.y, self.x.clone())
+    }
+}
+
 impl<N: Mul<N, N> + Sub<N, N>> Cross<Vec3<N>> for Vec3<N> {
     #[inline]
     fn cross(&self, other : &Vec3<N>) -> Vec3<N> {
@@ -24,6 +34,39 @@ impl<N: Mul<N, N> + Sub<N, N>> Cross<Vec3<N>> for Vec3<N> {
     }
 }
 
+impl<N: Neg<N> + Zero + Clone> CrossMatrix<Mat3<N>> for Vec3<N> {
+    #[inline]
+    fn cross_matrix(&self) -> Mat3<N> {
+        Mat3::new(
+            Zero::zero()  , -self.z,        self.y.clone(),
+            self.z.clone(), Zero::zero(),   -self.x,
+            -self.y       , self.x.clone(), Zero::zero()
+        )
+    }
+}
+
+// FIXME: iplement this for all other vectors
+impl<N: Clone> Row<Vec1<N>> for Vec2<N> {
+    #[inline]
+    fn row(&self, i: uint) -> Vec1<N> {
+        match i {
+            0 => Vec1::new(self.x.clone()),
+            1 => Vec1::new(self.y.clone()),
+            _ => fail!("Index out of range: 2d vectors do not have " + i.to_str() + " rows.")
+        }
+    }
+
+    #[inline]
+    fn set_row(&mut self, i: uint, r: Vec1<N>) {
+        match i {
+            0 => self.x = r.x,
+            1 => self.y = r.x,
+            _ => fail!("Index out of range: 2d vectors do not have " + i.to_str() + " rows.")
+
+        }
+    }
+}
+
 impl<N: One> Basis for Vec1<N> {
     #[inline(always)]
     fn canonical_basis(f: &fn(Vec1<N>) -> bool) {