matrices: moving another doctest to unit

rtchallenge/src/matrices.rs

@@ -140,38 +140,6 @@ impl PartialEq for Matrix3x3 {
 
 /// Matrix4x4 represents a 4x4 matrix in row-major form. So, element `m[i][j]` corresponds to m<sub>i,j</sub>
 /// where `i` is the row number and `j` is the column number.
-///
-/// # Examples
-/// ```
-/// use rtchallenge::{
-///     float::consts::PI,
-///     matrices::Matrix4x4,
-///     tuples::{point, vector},
-/// };
-///
-/// // Individual transformations are applied in sequence.
-/// let p = point(1., 0., 1.);
-/// let a = Matrix4x4::rotation_x(PI / 2.);
-/// let b = Matrix4x4::scaling(5., 5., 5.);
-/// let c = Matrix4x4::translation(10., 5., 7.);
-/// // Apply rotation first.
-/// let p2 = a * p;
-/// assert_eq!(p2, point(1., -1., 0.));
-/// // Then apply scaling.
-/// let p3 = b * p2;
-/// assert_eq!(p3, point(5., -5., 0.));
-/// // Then apply translation.
-/// let p4 = c * p3;
-/// assert_eq!(p4, point(15., 0., 7.));
-///
-/// // Chained transformations must be applied in reverse order.
-/// let p = point(1., 0., 1.);
-/// let a = Matrix4x4::rotation_x(PI / 2.);
-/// let b = Matrix4x4::scaling(5., 5., 5.);
-/// let c = Matrix4x4::translation(10., 5., 7.);
-/// let t = c * b * a;
-/// assert_eq!(t * p, point(15., 0., 7.));
-/// ```
 #[derive(Copy, Clone, Default)]
 pub struct Matrix4x4 {
     m: [[Float; 4]; 4],
@@ -529,6 +497,32 @@ mod tests {
         tuples::{point, vector},
     };
 
+    #[test]
+    fn example4x4() {
+        // Individual transformations are applied in sequence.
+        let p = point(1., 0., 1.);
+        let a = Matrix4x4::rotation_x(PI / 2.);
+        let b = Matrix4x4::scaling(5., 5., 5.);
+        let c = Matrix4x4::translation(10., 5., 7.);
+        // Apply rotation first.
+        let p2 = a * p;
+        assert_eq!(p2, point(1., -1., 0.));
+        // Then apply scaling.
+        let p3 = b * p2;
+        assert_eq!(p3, point(5., -5., 0.));
+        // Then apply translation.
+        let p4 = c * p3;
+        assert_eq!(p4, point(15., 0., 7.));
+
+        // Chained transformations must be applied in reverse order.
+        let p = point(1., 0., 1.);
+        let a = Matrix4x4::rotation_x(PI / 2.);
+        let b = Matrix4x4::scaling(5., 5., 5.);
+        let c = Matrix4x4::translation(10., 5., 7.);
+        let t = c * b * a;
+        assert_eq!(t * p, point(15., 0., 7.));
+    }
+
     #[test]
     fn translation() {
         let transform = Matrix4x4::translation(5., -3., 2.);