how does a source tree work

Question

when making large scale projects you may have a code file for graphics, sound, mechanics, i dont even know- but how do all the files communicate with eachother? if you used 2 different programs like visual studio and blender (just grabbing stuff off the top of my head), how do they know eachother exist?

looking for an article or a specific example with any programs, just want to understand how you could make a bigger project with many engines

Answer 1

They don't need to know about each other. You wouldn't want two toolkits for the same thing as they won't work together. But, toolkits for separate features can be combined. You are the one who must make them work together. Each toolkit has things your code must do to make them work for your project and you must figure out how to fit all of those things together.