JBEngine: GUI Progression

I have been working solely on the GUI aspect of my work for a while and have now come up with what is hopefully close to a final implementation. I've had to deal with issues to do with working in different spaces. i.e. converting from Mouse Co-ordinates and manipulating texture co-ordinates to finally get the final image in clip space co-ordinates. It has been tough and taken a few iterations to get it all right. 

I finally have a semi-finished example showing the use of GUI Buttons, Layovers and Text:

One of the more difficult decisions I made was deciding how to do the events for the GUI elements such as OnClickEvent. After doing some searching around I settled on using a C++ 11 feature the std::function. The important aspect of this feature is that it allows you to store a reference to a member function. Here is an example of how it is used: 

 //Create a function object for member function for this instance 
function<void()> myOnClickFnc = bind( &MyClass::FunctionName, this );
 //Then Set the OnClickFunction for my GuiElement
button->SetOnClickEvent( myOnClickFnc ); 

The main advantage of this is that it is now fairly easy for any class to set their own member functions to work as the event function for an element and it is much safer than using normal function pointers. The std::function does still work for normal functions and also static class functions, the only difference is that you wouldn't need to use the "bind()" function. so it would simply be:

 //Create a function object for static class function
  function<void()> myOnClickFnc = &MyStaticClass::FunctionName;
  

or:

 //Create a function object for function 
function<void()> myOnClickFnc = &functionName;
 //Then Set the OnClickFunction for my GuiElement
button->SetOnClickEvent( myOnClickFnc );
 

I have read online that this new feature can be quite slow although at the moment I haven't noticed any performance issues and as a general rule a GUI isn't as performance critical as other parts of a game.

This project is really coming along and I am now looking to tidy up some bits and really design how the "Engine" will be exposed to the user.

Keep coding :)