Question: What is a macro in GameMaker?

Answer

Macros in GameMaker are essentially constants. They are a way to define values that will not change throughout the execution of the game. Defining a macro happens at compile time, and the value associated with a macro name gets directly inserted into the code wherever it is used.

In GameMaker Studio 2, you create macros using the #macro directive, like so:

#macro SCREEN_WIDTH 1024
#macro SCREEN_HEIGHT 768

After these macros have been defined, you can use SCREEN_WIDTH and SCREEN_HEIGHT anywhere in your code, and GameMaker will treat them as if you had literally typed 1024 and 768.

For instance:

// Set the size of the application surface
surface_resize(application_surface, SCREEN_WIDTH, SCREEN_HEIGHT);

During compilation, GameMaker will replace SCREEN_WIDTH with 1024 and SCREEN_HEIGHT with 768, so the compiled code will be equivalent to:

surface_resize(application_surface, 1024, 768);

This is especially useful for values that are used frequently throughout your project and may need to be updated or changed. Instead of searching through your entire codebase to replace a value, you only need to update the macro definition.

Additionally, using macros can make your code more readable and maintainable, since names like SCREEN_WIDTH can provide more context than a raw number, making it clear what the purpose of the value is.