Merge pull request #90 from csherratt/translate

Add a translation builder to Matrix4

src/matrix.rs

@@ -250,6 +250,15 @@ impl<S: BaseNum> Matrix4<S> {
     pub fn identity() -> Matrix4<S> {
         Matrix4::from_value(one())
     }
+
+    /// Create a translation matrix from a Vector3
+    #[inline]
+    pub fn from_translation(v: &Vector3<S>) -> Matrix4<S> {
+        Matrix4::new(one(),  zero(), zero(), zero(),
+                     zero(), one(),  zero(), zero(),
+                     zero(), zero(), one(),  zero(),
+                     v.x,    v.y,    v.z,    one())
+    }
 }
 
 impl<S: BaseFloat>

src/test/matrix.rs

@@ -328,6 +328,14 @@ fn test_invert() {
     assert!(mat_f.invert().unwrap().mul_m(&mat_f).is_identity());
 }
 
+#[test]
+fn test_from_translation() {
+    let mat = Matrix4::from_translation(&Vector3::new(1.0f64, 2.0f64, 3.0f64));
+    let vertex = Vector4::new(0.0f64, 0.0f64, 0.0f64, 1.0f64);
+    let res = mat.mul_v(&vertex);
+    assert_eq!(res, Vector4::new(1., 2., 3., 1.));
+}
+
 #[test]
 fn test_predicates() {
     // Matrix2