transposition

matrix/src/lib.rs

@@ -55,6 +55,15 @@ impl Matrix {
             vec![0.0, 0.0, 0.0, 1.0],
         ])
     }
+
+    pub fn transpose(&mut self) {
+        self.matrix = vec![
+            vec![self.matrix[0][0], self.matrix[1][0], self.matrix[2][0], self.matrix[3][0], ],
+            vec![self.matrix[0][1], self.matrix[1][1], self.matrix[2][1], self.matrix[3][1], ],
+            vec![self.matrix[0][2], self.matrix[1][2], self.matrix[2][2], self.matrix[3][2], ],
+            vec![self.matrix[0][3], self.matrix[1][3], self.matrix[2][3], self.matrix[3][3], ],
+        ];
+    }
 }
 
 impl Index<usize> for Matrix {
@@ -313,4 +322,30 @@ mod tests {
 
         assert_eq!(Matrix::identity() * t, expected);
     }
+
+    #[test]
+    fn transposition() {
+        let mut m = Matrix::from_array([
+            [0.0, 9.0, 3.0, 0.0],
+            [9.0, 8.0, 0.0, 8.0],
+            [1.0, 8.0, 5.0, 3.0],
+            [0.0, 0.0, 5.0, 8.0],
+        ]);
+
+        let expected = Matrix::from_array([
+            [0.0, 9.0, 1.0, 0.0],
+            [9.0, 8.0, 8.0, 0.0],
+            [3.0, 0.0, 5.0, 5.0],
+            [0.0, 8.0, 3.0, 8.0],
+        ]);
+        m.transpose();
+        assert_eq!(m, expected);
+    }
+
+    #[test]
+    fn transpose_identity() {
+        let mut m = Matrix::identity();
+        m.transpose();
+        assert_eq!(m, Matrix::identity());
+    }
 }