godot - What does func _physics_process(delta), move_and_slide(), Vector2() and do in gdscript?

Question

I'm just started learning to program because I want to learn how to make a game. I choose the Godot engine to start making games but I can't understand what anything does. I have only understood the concept of variables and constants. I'm watching a couple of tutorials and copying exactly what the people in the video are doing but I don't just wanna copy and not understand anything, so could you please tell me what the above things even do?

Answer 1

The physics process is called during the physics processing step of the main loop. Physics processing means that the frame rate is synced to the physics, i.e. the delta variable should be constant which isn't the case if you just call _process(delta):

Vector2() is just a 2d vector, the first parameter for the x axis, the second for y. You can use it also as an boolean, Vector(0,0) always returns false, while every other point returns true.

move_and_slide() was designed as a special case, because a common use case was to calculate a slide vector along the collision. However, because it slides, it's possible for there to be more than one collision in a frame (think when you hit a corner between the floor and the wall. For this reason, it can't return a collision, so you need to use the get_slide_collision(). So it handles for example how your character react if he collides with an object.