Question

I’ve been doing extensive research on this topic for the past few days and I can’t seem to find an answer for my exact problem.

So, I have a simple game set up where I have the player at 0, 0 with a width of 10×10

    player= pygame.Rect(0, 0, 10, 10)

and aside from that, the player has a velocity of x: 0, y: 10, which will make him fall (y is positive because the origin of the screen is at the top left.)

and I have a tile at 0, 100, as shown:

    dirt= pygame.Rect(0, 100, 10, 10)

so, how can I handle collision, I already know I can detect it with Rect.colliderect(Rect).

I’ve tried a few ways, but encountered some problems:

I can’t cut the player’s velocity to 0 when he hits something and then move him
back until he’s just touching the object because that still causes the problem of walking, when he walks, I apply +10 velocity on x, but unfortunately, the game still processes that he is falling and colliding and moving sideways, so it just moves him back to where he started.

I’m a beginner, so a simple answer would be appreciated, and I would like to not have to use any third party modules other that pygame if I didn’t have to.

Update:

Here is some of the rough test code I have tried:

    def sim(obj, time, world):
        time= time / 1000
        obj.physProp['vel']= (obj.physProp['vel'][0] + (accel[0] * time), obj.physProp['vel'][1] + (accel[1] * time))
        if obj.physProp['vel'][1] > terminalY:
            obj.physProp['vel']= (obj.physProp['vel'][0], terminalY)
        obj.pos= (obj.pos[0] + (obj.physProp['vel'][0] * time) + ((accel[0] / 2) * (time ** 2)), obj.pos[1] + (obj.physProp['vel'][1] * time) + ((accel[1] / 2) * (time ** 2)))

        for ID in world:
            if obj.getRect().colliderect(world[ID].getRect()) == True:
                pass

        return (obj.pos, obj.physProp['vel'])

Answer 1

The Pygame API invites you to write all your game subjects in an Object oriented way – so that your falling character will have all the “methods” and “attributes” to properly respond to things on the scenario – like hitting something.

So, if your character is defined for something as simple as:

class Char(object):
    # these start as class attributes, 
    # but whenever they are assigned to with a "self.var = bla" in
    # a method, an instance attribute starts existing
    x, y = 0,0
    vx, vy = 0,0

    def update(self):
        self.x += self.vx
        self.y += self.vy

And your external code, upon detecting a collision, could do just this:

def mainloop():
   while True:
       ...
       obj.update()
       if obj.getRect().colliderect(world[ID].getRect()): # don't do "== True" in `if's - it is just silly
             # take character back to the precious position
             obj.x -= obj.vx
             obj.y -= obj.vy
             # zero out velocities to make it stop:
             obj.vx = obj.vy = 0

And so on – you will soon perceive thinking of your game “things” as “objects” as they are used in programing make the code flows quite naturally – as soon as you get the way this works, look at Pygame’s sprite module – which allows you to automate a lot of checks, and updates without having to explicitly write for loops for each check