matrices: implement Matrix4x4::translate

rtchallenge/src/matrices.rs

@@ -223,6 +223,32 @@ impl Matrix4x4 {
         }
     }
 
+    /// Creates a 4x4 matrix representing a translation of x,y,z.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rtchallenge::{matrices::Matrix4x4, tuples::Tuple};
+    ///
+    /// let transform = Matrix4x4::translate(5., -3., 2.);
+    /// let p = Tuple::point(-3., 4., 5.);
+    /// assert_eq!(transform * p, Tuple::point(2., 1., 7.));
+    ///
+    /// let inv = transform.inverse();
+    /// assert_eq!(inv * p, Tuple::point(-8., 7., 3.));
+    ///
+    /// let v = Tuple::vector(-3., 4., 5.);
+    /// assert_eq!(transform * v, v);
+    /// ```
+    pub fn translate(x: f32, y: f32, z: f32) -> Matrix4x4 {
+        Matrix4x4::new(
+            [1., 0., 0., x],
+            [0., 1., 0., y],
+            [0., 0., 1., z],
+            [0., 0., 0., 1.],
+        )
+    }
+
     /// Transpose self, returning a new matrix that has been reflected across the diagonal.
     /// # Examples
     ///