diff --git a/README.md b/README.md
index f7f1815..2379193 100755
--- a/README.md
+++ b/README.md
@@ -33,6 +33,9 @@ Player control is standard.
 
 <h4>Research source code:</h4>
 
+Structure:
+![Project demonstration](img/structure.png)
+
 1) Download and install OpenAL library for SFML sound support (in current version you can't setup this engine without OpenAL)
    
     openal: https://openal.org/downloads/
diff --git a/engine/Engine.h b/engine/Engine.h
index 9aa11a0..0874769 100755
--- a/engine/Engine.h
+++ b/engine/Engine.h
@@ -16,12 +16,12 @@
 class Engine {
 private:
     std::string _name;
+
     double _triPerSec = 0;
     bool _debugText = true;
     bool _updateWorld = true;
 
     void printDebugText() const;
-
 protected:
     std::shared_ptr<Screen> screen;
     std::shared_ptr<Keyboard> keyboard;
diff --git a/engine/utils/Matrix4x4.cpp b/engine/utils/Matrix4x4.cpp
index 9d966be..143bfd4 100755
--- a/engine/utils/Matrix4x4.cpp
+++ b/engine/utils/Matrix4x4.cpp
@@ -152,8 +152,6 @@ Matrix4x4 Matrix4x4::Rotation(Point4D v, double rv) {
     return Rv;
 }
 
-
-
 Matrix4x4 Matrix4x4::Projection(double fov, double aspect, double ZNear, double ZFar) {
     Matrix4x4 p{};
 
diff --git a/engine/utils/Matrix4x4.h b/engine/utils/Matrix4x4.h
index b66832c..7c04d88 100755
--- a/engine/utils/Matrix4x4.h
+++ b/engine/utils/Matrix4x4.h
@@ -11,6 +11,7 @@
 class Matrix4x4 {
 private:
     std::array<std::array<double, 4>, 4> _arr{};
+
 public:
     Matrix4x4 () = default;
     Matrix4x4& operator=(const Matrix4x4& matrix4X4) = default;
diff --git a/engine/utils/Point4D.cpp b/engine/utils/Point4D.cpp
index fea6de0..e8d8f86 100755
--- a/engine/utils/Point4D.cpp
+++ b/engine/utils/Point4D.cpp
@@ -67,7 +67,7 @@ Point4D Point4D::operator/(double number) const {
 // Other useful methods
 double Point4D::sqrAbs() const
 {
-    return x()*x() + y()*y() + z()*z() + w()*w();
+    return x()*x() + y()*y() + z()*z();
 }
 double Point4D::abs() const {
     return sqrt(sqrAbs());
diff --git a/engine/utils/Time.cpp b/engine/utils/Time.cpp
index 3616c7e..db50c35 100755
--- a/engine/utils/Time.cpp
+++ b/engine/utils/Time.cpp
@@ -15,7 +15,7 @@ namespace Time
     {
         // High precision time
         high_resolution_clock::time_point _start = high_resolution_clock::now();
-        high_resolution_clock::time_point _last;
+        high_resolution_clock::time_point _last = _start;
 
         // FPS counter
         high_resolution_clock::time_point _fpsStart;
diff --git a/img/structure.png b/img/structure.png
new file mode 100644
index 0000000..679fd85
Binary files /dev/null and b/img/structure.png differ