How to program game responses, e.g. If you use bone meal on grass in Minecraft, then plants grow, how do you program something like that?

How to program game responses, e.g. If you use bone meal on grass in Minecraft, then plants grow, how do you program something like that?

You bumble in a loop and wait for keys to be pressed. If, as in your example, right-click is pressed, then what is looked at and what is in the hand is evaluated again in order to then trigger the corresponding action in the program.