How to make an object move by itself in order to avoid collisions with other objects

Question

I'm making this game about dodging objects that come from different directions. What I'm trying to achieve is to get this object (a 'player' class controlled by the computer) to be able to dodge just like a player controlled by user would do.

I've tried to use basic collisions handling provided by pygame (of course, read some documentation about how it works and what could I do to solve the problem). What I did was basically check if an object's right rect position overlaps the 'player's' left rect and viceversa, so it moves to the opposite direction to avoid the collision.

TITLE = "Dodging-IA Attempt";
WIDTH = 320; HEIGHT = 400;
FPS = 60;

BLACK = (0,0,0); WHITE = (255,255,255);
RED = (255,0,0); GREEN = (0,255,0); BLUE = (0,0,255);

import pygame as pg;
import random, math;

class Game():
    def __init__(self):
        self.screen = pg.display.set_mode((WIDTH,HEIGHT));
        self.clock = pg.time.Clock(); self.dt = FPS/1000;
        self.running = True;
        self.all_sprites = pg.sprite.Group();
        self.bullets = pg.sprite.Group();
        self.other_sprites = pg.sprite.Group();

        self.player = Player(); self.all_sprites.add(self.player);
        self.bullet_spawn = BulletSpawn(); self.other_sprites.add(self.bullet_spawn);


class Player(pg.sprite.Sprite):
    def __init__(self):
        pg.sprite.Sprite.__init__(self);
        self.image = pg.Surface((16,32)); self.image.fill(GREEN);
        self.rect = self.image.get_rect();
        self.rect.centerx = WIDTH//2;
        self.rect.y = HEIGHT*3//4;
        self.vx = self.vy = 300;

    def update(self,dt):
        pass;

class Bullet(pg.sprite.Sprite):
    def __init__(self,x):
        pg.sprite.Sprite.__init__(self);
        self.image = pg.Surface((16,16)); self.image.fill(RED);
        self.rect = self.image.get_rect();
        self.rect.centerx = x;
        self.rect.bottom = 0;
        self.vy = 70;

    def update(self,dt):
        self.rect.y += self.vy * dt;
        if self.rect.top > HEIGHT:
            self.kill();

class BulletSpawn(pg.sprite.Sprite):
    def __init__(self):
        pg.sprite.Sprite.__init__(self);
        self.image = pg.Surface((1,1)); self.rect = self.image.get_rect();
        self.new_bullet = pg.time.get_ticks();

    def update(self):
        now = pg.time.get_ticks();
        if now - self.new_bullet > 500:
            self.new_bullet = now;
            for i in range(5):
                bullet = Bullet(random.randint(8,WIDTH-8));
                game.bullets.add(bullet);
                game.all_sprites.add(bullet);

pg.init();
pg.display.set_caption(TITLE);

game = Game();

while game.running:

    game.dt = game.clock.tick(FPS)/1000;

    for event in pg.event.get():
        if event.type == pg.QUIT:
            game.running = False;

    hits = pg.sprite.spritecollide(game.player,game.bullets,False)
    for hit in hits:
        if hit.rect.right > game.player.rect.left:  #dodge moving to left
            game.player.rect.x += game.player.vx*game.dt
            print("DODGED TO LEFT")
        if hit.rect.left < game.player.rect.right:  #dodge moving to right
            game.player.rect.x -= game.player.vx*game.dt
            print("DODGED TO RIGHT")


    game.all_sprites.update(game.dt);
    game.other_sprites.update();

    game.screen.fill(BLUE);
    game.all_sprites.draw(game.screen)
    game.other_sprites.draw(game.screen)
    pg.display.flip();

pg.quit();

As a result, the 'player' moves always to one and only one direction no matter if it collides or not in its path instead of actually dodging horizontally the falling objects. What could I do to get this? Maybe I have to reformulate the collision's conditions? Thank you so much for your time.

Unknown Unknown · Accepted Answer · 2019-07-06T23:58:35

Checking that the boxes edge is within the player span is a way to do this. If you make the check inclusive, the player should dodge even if only the edged are aligned.

if hit.rect.right >= game.player.rect.left and hit.rect.left <= game.player.rect.left:
    game.player.rect.x += game.player.vx*game.dt
    print("DODGED TO LEFT")
elif hit.rect.left <= game.player.rect.right and hit.rect.right >= game.player.rect.right:
    game.player.rect.x -= game.player.vx*game.dt
    print("DODGED TO RIGHT")

How to make an object move by itself in order to avoid collisions with other objects

2 Answers