Slot Machine Logic - A quick look

Most modern slot-machines or VLTs (Video Lottery Terminals), use a random number generator to determine the outcome of a given spin. Any "wheels" of a slot machine that you may see on these digital displays are purely for aesthetic, and do not influence the outcome.

When designing the odds for a slot machine, a spreadsheet as such is common to visualise each "wheel".

Eddie's Math and Calculator Blog

Each "slot" or "wheel" shows the count of each symbol. This would be nothing but code for a VLT, but for a physical wheel? It would look something like this:

I created these 3 wheels in Godot.

Inspired from real physical slot machines still found in modern arcades & some casinos. -- Credit: Pixels

So why am I using physical wheels? Well, it can look more fun in a game, especially when perfect odds aren't essential (when not using real money). In my case I am going for a fantasy style game, where large stone wheels have painted symbols on each square. My main focus is the logic behind the slot machine, and calculating winnings.

private void CalculateWinnings()
	{
		var symbols = CheckSymbols();

		if (symbols.All(s => s == symbols[0]))
		{
			if (MatchThreePayouts.TryGetValue(symbols[0], out int payout))
			{
				WinSlot(payout);
				return;
			}
			return;
		}
		else
		if (symbols[0] == symbols[1] || symbols[1] == symbols[2])
		{
			for (int i = 0; i < symbols.Length - 1; i++)
			{
				if (MatchTwoPayouts.TryGetValue(symbols[1], out int payout))
				{
					WinSlot(payout);
					return;
				}
				for (int p = 0; p < symbols.Length - 1; p++)
				{
					if (MatchSinglePayouts.TryGetValue(symbols[p], out int payout1))
					{
						WinSlot(payout1);
					}
				}
			}
		}
		else
		{
			for (int p = 0; p < symbols.Length; p++)
			{
				if (MatchSinglePayouts.TryGetValue(symbols[p], out int payout1))
				{
					WinSlot(payout1);
				}
			}	
		}
	}

	private string[] CheckSymbols()
	{
		var symbols = new[] { "null", "null", "null" };

		var i = 0;
		foreach (Node3D wheel in _wheels)
		{
			Debug.WriteLine("chek");
			_wheelCheckRays[i].ForceRaycastUpdate();
			if (_wheelCheckRays[i].IsColliding())
			{
				var col = _wheelCheckRays[i].GetCollider();
				if (col is Node3D node)
				{
					var sqr = node.GetParent<Square>();
					symbols[i] = sqr.ChosenSymbol.ToString().ToLower();
				}
			}
			i++;
		}
		return symbols;
	}

Here is my logic for calculating the winnings, I created a dictionary for each match type; single, double, triple matches. Each dictionary has a <string, int> structure and the name of the symbol gives the number in winnings, very easy to tweak. Whether or not you are interested in truly random results, I recommend employing strategies other than my own. I used 3 random floats to determine a speed at which each wheel spins, using the same deceleration value for each. This is just so I can test the part of the code that's more important to me, but note that after some research it seems like this does not create a perfectly random environment.

And here's the demo to my product! I succesfully accomplished my goal of using slot machine logic to calculate winnings. Please contact me if you would like a playable build for you to test. And that's what I got up to last week, thanks!