OpenGL – Abstraction of VAOs, VBOs, and Models

In functional programming, there is a concept called Map. Map is a higher-order function that applies a function to each element in a list.

In ordinary code, you would do something like:

var list = new List<int> { 1,2,3,4,5,6 };

var newList = new List<int>();

foreach(var item in list)
{
    newList.Add(item * 2);
}

// newList --> { 2,4,6,8,10,12 }

Rather than writing a loop each time, you create a Map method:

public List<T> Map<T>(this List<T> list, Func<T,TResult> function)
{
    var newList = new List<T>()

    foreach(T item in enumeration)
    {
        newList.Add(function(item));
    }

    return newList;
}

Now, instead of writing a loop each time, you can simply write:

var list = new List<int>() { 1,2,3,4,5,6 };

var modifiedList = Map(list, x => x * 2); // { 2,4,6,8,10,12 }

and get the same result.

The Map method is an abstraction over writing a loop to modify each member of a list.

I haven't mentioned it yet, but the <T> syntax is also an abstraction. It's called generics; it means that you can write a function that can operate on different data types, instead of writing functions for each data type.

All abstraction is a form of generalization: writing code that applies to more than one specific situation.

You said in your text that CreateSkyBox () was private, but its not declared private.

There is absolutely nothing wrong with having static 'helper' functions in a class, which are used to help with whatever makes sense - including creating auxiliary objects like the Model.

If it never makes sense to have an empty Model, then it should not have a no-argument constructor (exactly as you've done).

Though I think your code / approach is fine, there is another pattern you can use for similar circumstances. If you want to have mModel in an unconstructed (null) state - use optional instead of Model; Then you can construct it inside the body of your constructor. In your particular case, I believe what you've done is better, but if your needs change, and you need to be able to construct some objects (like Skybox) when you dont have all the data yet (when reading objects from a file is a common case where this can happen) - then using std::optional can help there.