Making a Loading Screen for a game

I will handle how to make a loading screen for a game using C# and SFML.Net. I think it covers other frameworks as well. I mean, you can make it with other C# graphics library or other some Java frameworks most probably. 

What's loading screen? The loading screen shows some information of the process that are necessary data for the game. These data can be world map, and generating a world map can take a noticeable amount of time. For example, Terraria, etc. Therefore, we need to use loading screen for that moment.

Normally, when I started the game, there is a blockage because of the generating something for the game. At this moment, we can not do anything with the window. If I click the window, the program might be crushed. Also, it does not give a good impression. 

I will keep my example very simple. Let's get to work.

Firstly, I'm going to use a thread for generating operation. So the map is generated in the another thread. Also, I need a text object. This object will be drawn to show the percentage of the generating map on the screen. I need to get information from the thread I created to use in the main thread. I created a class called SharedData for it:

    class SharedData
    {
        public int Progress {get; set;} = 0;
    }
    
    class Game
    {
        ...
        
        Thread thread;
        Text Percentage { get; set; }        
        public static SharedData shared = new SharedData();
        
        public Game(...)
        {
            ...
            
            Percentage = new Text("0%", font, 100);
            Percentage.Position = new Vector2f(-25, -25);
            Percentage.FillColor = Color.Black;
            
            thread = new Thread(GenerateMap);
            thread.Start();
        }

I defined the SharedData object as static because we need to access it from another thread easily. The shared variable is actually a global variable. I created the text object and named it as Percentage. After that, I created a thread called thread, and add GenerateMap method to the this thread. I started this thread with Start method. Let's use this shared variable in the Generate method:

        public void GenerateMap()
        {
            for(int i = 0; i < 4116; i++)
            {
                
                // generate data here
                
            	Game.shared.Progress = i; 
            }
       	}

I just track how many times the loop has run like in above. We need to use this data in the main thread for the loading screen. If the thread is alive then we can show the loading screen with percentage. That's so simple:

        ...

        public void update(float dt)
        {
            if(thread.IsAlive)
            {
                float calc = ((float)shared.Progress / 4116f) * 100;
                Percentage.DisplayedString = ((int)calc).ToString() + "%";
            }
            else
            {
                // update generated data
            }
        }

        public void draw(RenderTarget target)
        {
            if(thread.IsAlive)
            {
                target.Draw(Percentage);
            }
            else
            {
                // draw generated data
            }
        }

Let's see how it works: