Using functions for code that is used often within your game is great way to make it easier to read and quicker to update. Additionally, it makes it easier to organize and understand how your code works. A GML function is also useful in processing data, especially if you will be doing the same calculation again and again. This can include sending data to the script, processing it, and returning an outcome or variable. If you are using the same code twice or more anywhere in your program, then you should consider using a function. This allows you to make just one change to update your code everywhere. Imagine a game that had over 100 enemy monsters with their own code; changing the code for each would take many hours and be prone to errors. Using a function, you could do this in a few minutes. It also allows for nice and tidy code. A function also allows you to easily share code between different game projects (which is a must if you go on to a career in game making) – saving you potentially a lot of time.

A function needs to be declared before you can use it. There are a few choices when declaring it, I use the following method.

A function is basically a container that includes one or functions. Then, generally return a result, for example a variable, a resource name, true false, etc.

It’s good practice to give your function an appropriate name, so when you’re calling it is clear as to what it does.

Creating a Function

First create a function in Scripts assets, as shown in Figure 24-1.

A screenshot has a dropdown of various tools, and select script tool, which opens a sub-menu. Highlights create options from the sub menu.

You can then name the function and pop in some code, for example the following:

/// @function         get_total(value1,value2,value3)

/// @param {real}     real

/// @param {real}     real

/// @param {real}     real

function get_total(value1,value2,value3)

{

      var total=value1+value2+value3

      return total;

}

which returns a total of all three values.

This would look like that shown in Figure 24-2.

A screenshot of 9 line code. Introduce get total functions for three values. Add 3 values and execute the results of the total.

Useful Functions

You can also set up a function that will tell you what the given variable needs to be.

For example:

/// @function function_example(value1,value2,value3)

/// @param {real} value1

/// @param {real} value2

/// @param {real} value3

function function_example(value1,value2,value3)

{

      total=value1+value2+value3

      return total;

}

Then when typing function_example in an Event, you’ll see a reminder at the bottom, as shown in Figure 24-3.

A create window for Object 1 has 2 lines of code. It displays function examples for 3 values as 10, 23, and 99.

You can also set it to use a default value if an argument is not passed to the script, for example:

function draw_text_shadow(xx,yy,text,col=c_red)

{

      draw_set_font(font_text);

      draw_set_colour(col);

      draw_text(xx-2,yy-2,text);

      draw_set_colour(c_white);

      draw_text(xx,yy,text);

}

So the following would draw the text with a green shadow:

draw_text_shadow(200,200,"Example Text",c_green);

whereas this would draw a shadow with a red shadow:

draw_text_shadow(200,200,"Example Text");