I am creating tetris using pygame. i want to use collision detection so that when the shape in play comes into contact with any other previously played shapes, i can stop the shape, as per the logic of tetris. i came across pixel perfect collision using masks. i have followed some tutorials online, however the pixel detection returns true every time a new shape comes into play, not when any shapes collide. sorry in advance for the long code, its the bare minimum for the code to actually and still containing the game element of it. i think there is something wrong with my approach which is causing this error. I basically have a function that everytime the shape in play comes into contact with the 'floor' that shape is held in that position and a new shape is created. i think ive overcomplicated it, in turn creating this error. thanks in advance
import pygame
import sys
import shapelogic
pygame.init()
screensize = width, height = 800, 595
screen = pygame.display.set_mode(screensize)
background_image =pygame.image.load("/Users/marceason/PycharmProjects/Tetris/Wooden_background.jpg").convert_alpha()
myshape = 0
stop_movement = 0
blit_count = 0
stored_shapes = pygame.sprite.Group()
stored_shapes_with_coords = []
extra_blit_required = False
index = 0
count = 0
listofshapes = []
class shapemanager():
def __init__(self):
self.listofshapes = []
def create_another_instance(self):
global count
count += 1
string = "Shape_{0},".format(count)
another_shape = Shape(string)
self.listofshapes.append(another_shape)
global index
object = self.listofshapes[index]
index += 1
return object
def load_shape(self):
shape = self.create_another_instance()
shape.load_shapes()
class Shape(pygame.sprite.Sprite):
def __init__(self, name):
pygame.sprite.Sprite.__init__(self)
self.name = name
self.x = 50
self.y = 100
self.move_event = pygame.USEREVENT + 1
self.reached_bottom_event = pygame.USEREVENT + 2
self.one_sec_timer = 1000
self.half_sec_timer = 500
self.reachbottomflag = False
self.movement_possible = True
self.image = pygame.image.load(
"/Users/marceason/PycharmProjects/Tetris/Tetris_Shapes/Green_Shape_1_Position_1.png")
self.mask = pygame.mask.from_surface(self.image)
self.rect = self.image.get_rect()
def move_shape(self):
if self.movement_possible:
key_input = pygame.key.get_pressed()
if key_input[pygame.K_LEFT]:
self.x -= 16
if key_input[pygame.K_RIGHT]:
self.x += 16
if not self.reachbottomflag:
if key_input[pygame.K_DOWN]:
self.y += 16
def reachbottom(self):
if self.y >= 560:
self.reachbottomflag = True
def no_movement_possible(self):
self.movement_possible = False
def assign_shape():
global myshape
global stop_movement
myshape = sl.create_another_instance()
pygame.time.set_timer(myshape.move_event, myshape.one_sec_timer)
stop_movement = pygame.time.set_timer(myshape.reached_bottom_event, myshape.half_sec_timer)
def blit_used_shapes():
global screen
global blit_count
blit_count = len(stored_shapes_with_coords)
local_count = 0
while local_count < blit_count:
screen.blit(stored_shapes_with_coords[local_count][0], (stored_shapes_with_coords[local_count][1], stored_shapes_with_coords[local_count][2]))
local_count += 1
sl = shapemanager()
##### HERE IS THE PIXEL DETECTION #####
result = pygame.sprite.spritecollide(myshape, stored_shapes, False, pygame.sprite.collide_mask)
## Main loop ##
assign_shape()
while True:
for event in pygame.event.get():
if event.type == pygame.QUIT: sys.exit()
screen.blit(background_image, (0, 0))
screen.blit(myshape.image, (myshape.x, myshape.y))
myshape.move_shape()
key_input = pygame.key.get_pressed()
if key_input[pygame.K_SPACE]:
myshape.rotate_shape()
myshape.reachbottom()
if myshape.reachbottomflag:
if event.type == myshape.reached_bottom_event:
myshape.no_movement_possible()
stored_shape_tuple = [myshape.image, myshape.x, myshape.y]
stored_shapes_with_coords.append(stored_shape_tuple)
stored_shapes.add(myshape)
extra_blit_required = True
assign_shape()
####### PIXEL DETECTION IS HERE IN FOR LOOP ####
if result:
print("this should only execute when two shapes touch!!")
if extra_blit_required:
blit_used_shapes()
pygame.display.update()
The issue is that you are not updating the sprites rect attribute. The sprites rects all have position (0, 0) (since you do not set it in the call to self.image.get_rect()) and as a result the masks will all overlap and collide.
If you read the docs for pygame.sprite.collide_mask you will note that it says that your sprites need to have mask and rect attributes. You have a rect in your sprite and you set it in the __init__(), but you do not keep it updated when you move the sprite. You just change the x and y attributes without adjusting the rect position. The reason that the collide_mask wants a rect is that it uses that to determine the offset parameter for the pygame.mask.Mask.overlap() call that it uses. The important thing to realize is that masks themselves do not have a position, they need the rects to determine the relative positions of the masks.
This is similar to images/surfaces not having a position and needing a rect to track that for them.
On a separate issue, the way you are blit'ing the sprites to the screen makes no sense. You are not using the abilities of the sprite groups to draw and worse you are keeping the image, x and y of the sprite in a separate list and not containing it in the sprite itself. You should go look at some examples of pygame sprite based code. There are lots of examples out there.