diff --git a/src/gamematrix.cpp b/src/gamematrix.cpp
index e69de29..ae65a96 100644
--- a/src/gamematrix.cpp
+++ b/src/gamematrix.cpp
@@ -0,0 +1,36 @@
+#include "gamematrix.h"
+#include <cmath>
+
+namespace Matrix3D {
+
+    Mat4 identity() {
+        Mat4 m{};
+        for(int i = 0; i < 4; i++) {
+            for(int j = 0; j < 4; j++) {
+                m[i][j] = (i == j) ? 1.0 : 0.0;
+            }
+        }
+        return m;
+    }
+
+    Mat4 matmul(const Mat4& A, const Mat4& B) {
+        Mat4 R{};
+        for(int i = 0; i < 4; i++) {
+            for(int j = 0; j < 4; j++) {
+                double sum = 0.0;
+                for(int k = 0; k < 4; k++) {
+                    sum += A[i][k] * B[k][j];
+                }
+                R[i][j] = sum;
+            }
+        }
+        return R;
+    }
+
+    Mat4 translate(const Vec3& pos) {
+        Mat4 t = identity();
+        t[0][3] = pos.x;
+        t[1][3] = pos.y;
+        t[2][3] = pos.z;
+        return t;
+    }