1 files changed, 237 insertions, 0 deletions
diff --git a/mons_math/src/mat3.c b/mons_math/src/mat3.c
new file mode 100644
index 0000000..f806375
--- /dev/null
+++ b/mons_math/src/mat3.c
@@ -0,0 +1,237 @@
+#include "mons_math/mat3.h"
+#include "mons_math/mat2.h"
+#include "mons_math/vec3.h"
+
+const mons_mat3 MONS_MAT3_ZERO = {
+    {0, 0, 0},
+    {0, 0, 0},
+    {0, 0, 0},
+};
+
+const mons_mat3 MONS_MAT3_IDENTITY = {
+    {1, 0, 0},
+    {0, 1, 0},
+    {0, 0, 1},
+};
+
+mons_mat3 mons_mat3_add(mons_mat3 a, mons_mat3 b) {
+    mons_mat3 result = {
+        mons_vec3_add(a.m1, b.m1),
+        mons_vec3_add(a.m2, b.m2),
+        mons_vec3_add(a.m3, b.m3),
+    };
+    return result;
+}
+
+void mons_mat3_add_inplace(mons_mat3 *a, mons_mat3 b) {
+    mons_vec3_add_inplace(&a->m1, b.m1);
+    mons_vec3_add_inplace(&a->m2, b.m2);
+    mons_vec3_add_inplace(&a->m3, b.m3);
+}
+
+mons_mat3 mons_mat3_mul_f(mons_mat3 a, float b) {
+    mons_mat3 result = {
+        mons_vec3_mul_f(a.m1, b),
+        mons_vec3_mul_f(a.m2, b),
+        mons_vec3_mul_f(a.m3, b),
+    };
+    return result;
+}
+
+mons_mat3 mons_mat3_mul_i(mons_mat3 a, int b) {
+    mons_mat3 result = {
+        mons_vec3_mul_i(a.m1, b),
+        mons_vec3_mul_i(a.m2, b),
+        mons_vec3_mul_i(a.m3, b),
+    };
+    return result;
+}
+
+mons_mat3 mons_mat3_mul(mons_mat3 a, mons_mat3 b) {
+    mons_vec3 b_n1 = mons_mat3_n1(b);
+    mons_vec3 b_n2 = mons_mat3_n2(b);
+    mons_vec3 b_n3 = mons_mat3_n3(b);
+
+    mons_mat3 result = {
+        {
+            mons_vec3_dot(a.m1, b_n1),
+            mons_vec3_dot(a.m1, b_n2),
+            mons_vec3_dot(a.m1, b_n3),
+        },
+        {
+            mons_vec3_dot(a.m2, b_n1),
+            mons_vec3_dot(a.m2, b_n2),
+            mons_vec3_dot(a.m2, b_n3),
+        },
+        {
+            mons_vec3_dot(a.m3, b_n1),
+            mons_vec3_dot(a.m3, b_n2),
+            mons_vec3_dot(a.m3, b_n3),
+        },
+    };
+    return result;
+}
+
+void mons_mat3_mul_f_inplace(mons_mat3 *a, float b) {
+    mons_vec3_mul_f_inplace(&a->m1, b);
+    mons_vec3_mul_f_inplace(&a->m2, b);
+    mons_vec3_mul_f_inplace(&a->m3, b);
+}
+
+void mons_mat3_mul_i_inplace(mons_mat3 *a, int b) {
+    mons_vec3_mul_i_inplace(&a->m1, b);
+    mons_vec3_mul_i_inplace(&a->m2, b);
+    mons_vec3_mul_i_inplace(&a->m3, b);
+}
+
+mons_mat3 mons_mat3_transpose(mons_mat3 a) {
+    mons_mat3 result = {
+        mons_mat3_n1(a),
+        mons_mat3_n2(a),
+        mons_mat3_n3(a),
+    };
+}
+
+void mons_mat3_transpose_inplace(mons_mat3 *a) { *a = mons_mat3_transpose(*a); }
+
+mons_vec3 mons_mat3_n1(mons_mat3 a) {
+    mons_vec3 result = {
+        a.m1.x,
+        a.m2.x,
+        a.m3.x,
+    };
+    return result;
+}
+
+mons_vec3 mons_mat3_n2(mons_mat3 a) {
+    mons_vec3 result = {
+        a.m1.y,
+        a.m2.y,
+        a.m3.y,
+    };
+    return result;
+}
+
+mons_vec3 mons_mat3_n3(mons_mat3 a) {
+    mons_vec3 result = {
+        a.m1.z,
+        a.m2.z,
+        a.m3.z,
+    };
+    return result;
+}
+
+float mons_mat3_determinant(mons_mat3 a) {
+    /*
+     *  a * det(
+     *   e f
+     *   h i
+     *  )
+     *  - b * det(
+     *     d f
+     *     g i
+     *  )
+     *  + c * det(
+     *     d e
+     *     g h
+     *  )
+     */
+    mons_mat2 efhi = {
+        {a.m2.y, a.m2.z},
+        {a.m3.y, a.m3.z},
+    };
+    mons_mat2 dfgi = {
+        {a.m2.x, a.m2.z},
+        {a.m3.x, a.m3.z},
+    };
+    mons_mat2 degh = {
+        {a.m2.x, a.m2.y},
+        {a.m3.x, a.m3.y},
+    };
+
+    return (a.m1.x * mons_mat2_determinant(efhi)) -
+           (a.m1.y * mons_mat2_determinant(dfgi)) +
+           (a.m1.z * mons_mat2_determinant(degh));
+}
+
+mons_mat3 mons_mat3_minor(mons_mat3 a) {
+    // Get determinants of minors
+    // First row elements
+    mons_mat2 minor_1_1 = {
+        {a.m2.y, a.m2.z},
+        {a.m3.y, a.m3.z},
+    };
+    float det_1_1 = mons_mat2_determinant(minor_1_1);
+    mons_mat2 minor_1_2 = {
+        {a.m2.x, a.m2.z},
+        {a.m3.x, a.m3.z},
+    };
+    float det_1_2 = mons_mat2_determinant(minor_1_2);
+    mons_mat2 minor_1_3 = {
+        {a.m2.x, a.m2.y},
+        {a.m3.x, a.m3.y},
+    };
+    float det_1_3 = mons_mat2_determinant(minor_1_3);
+    // Second row elements
+    mons_mat2 minor_2_1 = {
+        {a.m1.y, a.m1.z},
+        {a.m3.y, a.m3.z},
+    };
+    float det_2_1 = mons_mat2_determinant(minor_2_1);
+    mons_mat2 minor_2_2 = {
+        {a.m1.x, a.m1.z},
+        {a.m3.x, a.m3.z},
+    };
+    float det_2_2 = mons_mat2_determinant(minor_2_2);
+    mons_mat2 minor_2_3 = {
+        {a.m1.x, a.m1.y},
+        {a.m3.x, a.m3.y},
+    };
+    float det_2_3 = mons_mat2_determinant(minor_2_3);
+    // Third row elements
+    mons_mat2 minor_3_1 = {
+        {a.m1.y, a.m1.z},
+        {a.m2.y, a.m2.z},
+    };
+    float det_3_1 = mons_mat2_determinant(minor_3_1);
+    mons_mat2 minor_3_2 = {
+        {a.m1.x, a.m1.z},
+        {a.m2.x, a.m2.z},
+    };
+    float det_3_2 = mons_mat2_determinant(minor_3_2);
+    mons_mat2 minor_3_3 = {
+        {a.m1.x, a.m1.y},
+        {a.m2.x, a.m2.y},
+    };
+    float det_3_3 = mons_mat2_determinant(minor_3_3);
+
+    mons_mat3 result = {
+        {det_1_1, det_1_2, det_1_3},
+        {det_2_1, det_2_2, det_2_3},
+        {det_3_1, det_3_2, det_3_3},
+    };
+    return result;
+}
+
+mons_mat3 mons_mat3_cofactor(mons_mat3 a) {
+    mons_mat3 result = mons_mat3_minor(a);
+    result.m1.y *= -1;
+    result.m2.x *= -1;
+    result.m2.z *= -1;
+    result.m3.y *= -1;
+    return result;
+}
+
+mons_mat3 mons_mat3_adjoint(mons_mat3 a) {
+    return mons_mat3_transpose(mons_mat3_cofactor(a));
+}
+
+mons_mat3 mons_mat3_inverse(mons_mat3 a) {
+    return mons_mat3_mul_f(mons_mat3_adjoint(a),
+                           1.0 / mons_mat3_determinant(a));
+}
+
+int mons_mat3_equal(mons_mat3 a, mons_mat3 b) {
+    return mons_vec3_equal(a.m1, b.m1) && mons_vec3_equal(a.m2, b.m2) &&
+           mons_vec3_equal(a.m3, b.m3);
+}