my colliderect isnt working

Question

so i wrote small game where you have to dodge things but then i saw colliderect function and i wantet to change hard coded collusion with simply colliderect code. i set it up but it didnt wokred so i tested it and created new pygame file!

import pygame
w=400;h=400
pygame.init()
root=pygame.display.set_mode((w,h))
pygame.display.set_caption('TEST SUBJECT')
def gameloop():
    thing=pygame.image.load('unnamed.png')
    th=thing.get_rect()
    thing2=pygame.image.load('s.png')
    th2=thing2.get_rect()
    clock=pygame.time.Clock()
    while 1:
        for event in pygame.event.get():
            if event.type==pygame.QUIT:
                pygame.quit()
                quit()
            root.blit(thing,(w//2-50,h//2-60))
            root.blit(thing2,(0,0))
        if th.colliderect(th2)==1:
            print('OK')
        pygame.display.update()
        clock.tick(15)
gameloop()

as you can say here colliderect returns 1 even tho two object doesnt hit each other.

Answer 1

They hit each other because you don't change th and th2.

It doesn't matter that you display it in different places.

Try

 root.blit(thing, th) 
 root.blit(thing, th2) 

and you see that they collide.

You have to change th.x, th.y or th2.x, th.y to change position and then th.colliderect(th2) will work.

---

EDIT: full working example

import pygame

# --- constants --- (UPPER_CASE names)

WIDTH = 400
HEIGHT = 400

BLACK = ( 0, 0, 0)

FPS = 25

# --- main --- (lower_case names)

# - init -

pygame.init()

root = pygame.display.set_mode((WIDTH, HEIGHT))
root_rect = root.get_rect()

# - objects -

thing1 = pygame.image.load('ball-1.png')
thing1_rect = thing.get_rect()

thing2 = pygame.image.load('ball-2.png')
thing2_rect = thing2.get_rect()

# move things
thing1_rect.left = root_rect.left
thing1_rect.centery = root_rect.centery

thing2_rect.right = root_rect.right
thing2_rect.centery = root_rect.centery

# - mainloop -

clock = pygame.time.Clock()

while True:

    # - events -

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            quit()

    # - updates (without draws) -

    # move objects
    thing1_rect.x += 5
    thing2_rect.x -= 5

    # check collisions
    if thing1_rect.colliderect(thing2_rect):
        print('Collision')

    # - draws (without updates) -

    root.fill(BLACK)
    root.blit(thing1, thing1_rect)
    root.blit(thing2, thing2_rect)

    pygame.display.update()

    # - FPS -

    clock.tick(FPS)

ball-1.png

ball-2.png