How to implement moving enemys in pygame

Question

I am trying to implement a moving enemy that moves from side to side and when coming into contact with a platform changes direction and moves the other way. I have managed to make my enemy platform move in one direction but i cant seem to figure out a way to make it do the above.

Asked By: Sean Steinberg

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Answer 1

It’s hard to follow the code. Would be great if you post the relevant portion of codes next time.

This is not the absolute solution to your problem, but I hope this gives an idea. You are ought to check for 2 things: (1) if there’s a tile obstructing your way and (2) if there’s no tile/ground ahead to walk on unless you want your enemy object to fall.

Tile/Wall obstruction: You create an rect object in front of your enemy object and check for collision between that rect and the tiles.
No ground ahead: You create a small rect object at bottom-right and/or bottom-left of your enemy object and check for collision between that small rect and the tiles.

Below is a sample code. Haven’t tried running it so there may be a bug. But the idea should be there.

class Enemy:

    def __init__(self, pos: Tuple[float, float], x_vel: float):
        self.image = pygame.image.load("some_image.png").convert()
        self.rect = self.image.get_rect()
        self.rect.x, self.rect.y = pos
        self.x_vel = x_vel

    def update(self, tiles: List[Tile]):
        for tile in tiles:
            # check for tile obstructions
            future_enemy_rect = (self.rect.x + self.x_vel, self.rect.y, self.rect.width, self.rect.height)
            if tile.rect.colliderect(future_enemy_rect):
                self.x_vel *= -1

            # check if there's no tile ground ahead: create a small 8x8 or any arbitrary rect at bottom right and left of the enemy
            bottom_right_enemy_rect = (self.rect.right, self.rect.bottom, 8, 8)
            bottom_left_enemy_rect = (self.rect.x - 8, self.rect.bottom, 8, 8)
            if (not tile.rect.colliderect(bottom_right_enemy_rect)) or (not tile.rect.colliderect(bottom_left_enemy_rect)):
                self.x_vel *= -1

There may also be other approach to this which I am not aware of.

Answered By: Jobo Fernandez

How to implement moving enemys in pygame

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