How to Check for Collision in Pygame

Question

I tried to make some code run when two boxes collide with each other in Pygame, but somehow it is not working.

Game Declarations

class coin:
def __init__(self, x, y, height, width):
    self.x = x
    self.y = y
    self.x2 = x + width
    self.y2 = y + height
    self.height = height
    self.width = width
x = 50
y = 50
width = 20
height = 20
x2 = x + width
y2 = y + height
vel = 10
newCoin = coin(0,0,0,0)
needCoin = True

def generateCoin():
    randX = math.floor(random.random() * 100)
    randY = math.floor(random.random() * 100)
    print(randX)
    print(randY)
    return coin(randX, randY, 10, 10)

Game Display

if ((x < newCoin.x2) and (newCoin.x < x2) and (y2 > newCoin.y) and (newCoin.y2 > y)):
        print("Colliding")
        needCoin = True
        pygame.time.delay(100)

    pygame.draw.rect(win, (0,255,0), (newCoin.x,newCoin.y,newCoin.width,newCoin.height))
    pygame.display.update()

Answer 1

I recommend to use pygame.Rect and .coliderect():

coin_rect = pygame.Rect(newCoin.x, newCoin.y, newCoin.width, newCoin.height)
rect_2 = pygame.Rect(x, y, width, height)

if coin_rect.colliderect(rect_2):
    print("Colliding")
    needCoin = True
    pygame.time.delay(100) 

If you want to make your code work, then you have to ensure that self.x2, self.y2 respectively x2 and y2 is up to date. That you have to update this variables when ever self.x, self.y respectively x, y changes.

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Anyway I recommend to use pygame.Rect instead of x, y, width and height:

class coin:
    def __init__(self, x, y, height, width):
        self.rect = pygame.Rect(x, y, height, width)

def generateCoin():
    randX = math.floor(random.random() * 100)
    randY = math.floor(random.random() * 100)
    print(randX)
    print(randY)
    return coin(randX, randY, 10, 10)

test_rect = pygame.Rect(50, 50, 20, 20)
vel = 10
newCoin = generateCoin()
needCoin = True

if newCoin.rect.colliderect(test_rect):
    print("Colliding")
    needCoin = True
    pygame.time.delay(100)

pygame.draw.rect(win, (0,255,0), newCoin.rect)
pygame.display.update()