From a4ffb3b7d67cb8fbec7cdcf0ab6d61d4fb30cc4b Mon Sep 17 00:00:00 2001
From: Jon Janzen <jonjanzen@me.com>
Date: Fri, 2 Apr 2021 18:49:39 -0600
Subject: [PATCH] Inverse tests, and Mul is references

---
 matrix/src/lib.rs | 80 ++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 72 insertions(+), 8 deletions(-)

diff --git a/matrix/src/lib.rs b/matrix/src/lib.rs
index 1a226af..cee8ce7 100644
--- a/matrix/src/lib.rs
+++ b/matrix/src/lib.rs
@@ -174,10 +174,10 @@ impl Matrix {
     }
 }
 
-impl std::ops::Mul<Matrix> for Matrix {
+impl std::ops::Mul<&Matrix> for &Matrix {
     type Output = Matrix;
 
-    fn mul(self, _rhs: Matrix) -> Matrix {
+    fn mul(self, _rhs: &Matrix) -> Matrix {
         let mut result: Vec<Vec<f32>> = Vec::with_capacity(self.matrix.len());
         for row in 0..self.matrix.len() {
             let width = self.matrix[row].len();
@@ -192,10 +192,10 @@ impl std::ops::Mul<Matrix> for Matrix {
 
 }
 
-impl std::ops::Mul<Tuple> for Matrix {
+impl std::ops::Mul<&Tuple> for &Matrix {
     type Output = Tuple;
 
-    fn mul(self, _rhs: Tuple) -> Tuple {
+    fn mul(self, _rhs: &Tuple) -> Tuple {
         Tuple::new(
             self.calc_val_for_mul_tuple(0, &_rhs),
             self.calc_val_for_mul_tuple(1, &_rhs),
@@ -341,7 +341,7 @@ mod tests {
             [16.0, 26.0, 46.0, 42.0],
         ]);
 
-        assert_eq!(matrix_a * matrix_b, expected);
+        assert_eq!(&matrix_a * &matrix_b, expected);
     }
 
     #[test]
@@ -356,7 +356,7 @@ mod tests {
         let tuple = Tuple::new(1.0, 2.0, 3.0, 1.0);
         let expected = Tuple::new(18.0, 24.0, 33.0, 1.0);
 
-        assert_eq!(matrix * tuple, expected);
+        assert_eq!(&matrix * &tuple, expected);
     }
 
     #[test]
@@ -375,7 +375,7 @@ mod tests {
             [4.0, 8.0, 16.0, 32.0,]
         ]);
 
-        assert_eq!(matrix * Matrix::identity(4), expected);
+        assert_eq!(&matrix * &Matrix::identity(4), expected);
     }
 
     #[test]
@@ -383,7 +383,7 @@ mod tests {
         let t = Tuple::new(1.0, 2.0, 3.0, 4.0);
         let expected = Tuple::new(1.0, 2.0, 3.0, 4.0);
 
-        assert_eq!(Matrix::identity(4) * t, expected);
+        assert_eq!(&Matrix::identity(4) * &t, expected);
     }
 
     #[test]
@@ -580,4 +580,68 @@ mod tests {
 
         assert_matrix_eq(&expected, &b, 0.0001);
     }
+
+    #[test]
+    fn inverse_2() {
+        let m = Matrix::from_array([
+            [8.0, -5.0, 9.0, 2.0],
+            [7.0, 5.0, 6.0, 1.0],
+            [-6.0, 0.0, 9.0, 6.0],
+            [-3.0, 0.0, -9.0, -4.0],
+        ]).inverse();
+
+        let expected = Matrix::from_array([
+            [-0.15385, -0.15385, -0.28205, -0.53846],
+            [-0.07692, 0.12308, 0.02564, 0.03077],
+            [0.35897, 0.35897, 0.43590, 0.92308],
+            [-0.69321, -0.69321, -0.76923, -1.92308],
+        ]);
+
+        assert_matrix_eq(&expected, &m, 0.01);
+    }
+
+    #[test]
+    fn inverse_3() {
+        let m = Matrix::from_array([
+            [9.0, 3.0, 0.0, 9.0],
+            [-5.0, -2.0, -6.0, -3.0],
+            [-4.0, 9.0, 6.0, 4.0],
+            [-7.0, 6.0, 6.0, 2.0],
+        ]).inverse();
+
+        let expected = Matrix::from_array([
+            [-0.04074, -0.07778, 0.14444, -0.22222],
+            [-0.07778, 0.03333, 0.36667, -0.33333],
+            [-0.02901, -0.14630, -0.10926, 0.12963],
+            [0.17778, 0.06667, -0.26667, 0.33333],
+        ]);
+
+        assert_matrix_eq(&expected, &m, 0.01);
+    }
+
+    #[test]
+    fn multiply_by_inverse() {
+        let a = Matrix::from_array([
+            [3.0, -9.0, 7.0, 3.0],
+            [3.0, -8.0, 2.0, -9.0],
+            [-4.0, 4.0, 4.0, 1.0],
+            [-6.0, 5.0, -1.0, 1.0],
+        ]);
+        let b = Matrix::from_array([
+            [8.0, 2.0, 2.0, 2.0],
+            [3.0, -1.0, 7.0, 0.0],
+            [7.0, 0.0, 5.0, 4.0],
+            [6.0, -2.0, 0.0, 5.0],
+        ]);
+
+        let c = &a * &b;
+        let r = &c * &b.inverse();
+        let expected = Matrix::from_array([
+            [3.0, -9.0, 7.0, 3.0],
+            [3.0, -8.0, 2.0, -9.0],
+            [-4.0, 4.0, 4.0, 1.0],
+            [-6.0, 5.0, -1.0, 1.0],
+        ]);
+        assert_matrix_eq(&r, &expected, 0.00001);
+    }
 }