enemy AI collision detection isn't working - pygame

Question

My enemy AI isn't detecting collisions. I have been using the code that I use for my player collision detection. I tweaked it to fit the enemy, however it isn't working:
class Enemy(Entity):
def __init__(self, x, y,player):
pygame.sprite.Sprite.__init__(self)
self.image = Surface((32, 32))
self.xvel = 0
self.yvel = 0
self.image.fill(Color("#FF0000")) #Enemy is red
self.onGorund = False
#Enemy is 32 * 32 pixels
self.image.convert()
self.rect = Rect(x, y, 32, 32)
self.counter = 0 #counter variable
self.player = player
def move(self, speed = 5): # chase movement
if self.rect.x > self.player.rect.x: # Movement along x direction
self.rect.x -= speed
elif self.rect.x < self.player.rect.x:
self.rect.x += speed
if self.rect.y < self.player.rect.y: # Movement along y direction
self.rect.y += speed
elif self.rect.y > self.player.rect.y:
self.rect.y -= speed
def collide(self, xvel, yvel, platforms):
for p in platforms:
if pygame.sprite.collide_rect(self, p):
if isinstance(p, Player_class):
pygame.quit()
sys.exit()
if xvel > 0:
self.rect.right = p.rect.left
print ("collide right")
if xvel < 0:
self.rect.left = p.rect.right
print ("collide left")
if yvel > 0:
self.rect.bottom = p.rect.top
self.onGround = True
self.yvel = 0
if yvel < 0:
self.rect.top = p.rect.bottom
def update(self, platforms):
if up:
if self.onGround: self.yvel -= 10 #only jump if player is on the ground
if down:
pass
if running:
self.xvel = 12
if left:
self.xvel = -8
if right:
self.xvel = 8
if not self.onGround:
self.yvel += 0.3 #only accelerate with gravity if in the air
if self.yvel > 100: self.yvel = 100 #terminal velocity = 100
if not(left or right):
self.xvel = 0
self.rect.left += self.xvel #falls or jumps
self.collide(self.xvel, 0, platforms) #creates collisions along the x axis
self.rect.top += self.yvel #creates collisions along the y axis
self.onGround = False; #assumes that the player is in the air
# do y-axis collisions
self.collide(0, self.yvel, platforms)
I have been trying to make the window close whenever the enemy touches the player, problem being, if the enemy doesn't know that it's touching the player, it can't close the window. Please ask if more code is required.

Answer 1

There are a few things that need to be changed.
In the move method you should set the velocity (self.xvel and self.yvel) instead of moving the rect directly.
Then call the move method in the update method, move the rect of the sprite and handle the collisions. Also, you need to call the update method in the main function now instead of move and pass the platforms list:
enemy_list.draw(screen)
for e in enemy_list:
e.update(platforms)
In the collide method you check if one of the platforms is the player instance:
for p in platforms:
if pygame.sprite.collide_rect(self, p):
if isinstance(p, Player_class):
pygame.quit()
sys.exit()
However, the player sprite isn't in this list, so it can't collide.
The enemy actually has a reference to the player (self.player) so you can just do this to check if they collide:
if pygame.sprite.collide_rect(self, self.player):
or:
if self.rect.colliderect(self.player.rect):
Here's a complete example (I took the code from your previous question and tried to improve a few more things):
import sys
import pygame
from pygame.locals import *
win_height = 750 #height of window is 750 pixles
win_width = 1050 #height of window is 1050 pixels
half_win_width = int(win_width / 2) #will be used to centre camera
half_win_height = int(win_height / 2)
display = (win_width, win_height) #creates the window as 500*500 pixels
depth = 32 #prevents infinate recursion
flags = 0 #message to Les: I don't really know what this does, however I have seen it in many places being used, therefore I assumed that it was important
camera_slack = 30 #how many pixels the player can move before the camera moves with them
pygame.init()
def main(): #main game function
global cameraX, cameraY
pygame.init()
screen = pygame.display.set_mode(display, flags, depth)
pygame.display.set_caption("Super Castlevania Man")
timer = pygame.time.Clock()
move_cameraX = 0
move_cameraY = 0
up = down = left = right = running = False
background = pygame.Surface((32,32)) #the background takes up space on the screen
background.convert()
background.fill(pygame.Color("#000000")) #background is black
entities = pygame.sprite.Group()
player = Player_class(32, 32*15) #the player is 32*32 pixels large
platforms = []
x = y = 0
level = [
"PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP",
"P P",
"P E P",
"P P",
"P PPPPPPPPP P",
"P P",
"P P",
"P P",
"P PPPPPPPP P",
"P P",
"P PPPP P",
"P PPPPPP P",
"P PPPPPPP P",
"P P",
"P PPPPPP P",
"P P",
"P PPPPPPPPPPP P",
"P P",
"P PPPPPPPPPPP P",
"P P",
"P P",
"P P",
"P P",
"PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP",
]
#builds the level
for row in level:
for col in row:
if col == "P":
p = Platform(x, y) #makes P a solid object
platforms.append(p)
entities.add(p)
if col == "E":
e = Exit_block(x, y)
platforms.append(e)
entities.add(e)
x += 32
y += 32
x = 0
entities.add(player)
enemy = Enemy(60, 200, player) #Spawns enemy
enemy_list = pygame.sprite.Group() #creates an enemy group
enemy_list.add(enemy) #Add an enemy to the group
while 1:
timer.tick(60) #makes game run at 60 frames per second
for e in pygame.event.get(): #shortens event to e
if e.type == QUIT:
return
if e.type == KEYDOWN and e.key == K_ESCAPE:
return
if e.type == KEYDOWN and e.key == K_UP:
up = True
move_cameraY = -10
if e.type == KEYDOWN and e.key == K_DOWN:
down = True
move_cameraY = 10
if e.type == KEYDOWN and e.key == K_LEFT:
left = True
move_cameraX = -10
if e.type == KEYDOWN and e.key == K_RIGHT:
right = True
move_cameraX = 10
if e.type == KEYDOWN and e.key == K_SPACE:
running = True
if e.type == KEYUP and e.key == K_UP:
up = False
move_cameraY = 0
if e.type == KEYUP and e.key == K_DOWN:
down = False
move_cameraY = 0
if e.type == KEYUP and e.key == K_RIGHT:
right = False
move_cameraX = 0
if e.type == KEYUP and e.key == K_LEFT:
left = False
move_cameraX = 0
if e.type == KEYUP and e.key == K_RIGHT:
right = False
# Update the game.
for e in enemy_list:
e.update(platforms)
player.update(up, down, left, right, running, platforms)
# Draw everything.
for y in range(32): #draws the background
for x in range(32):
screen.blit(background, (x * 32, y * 32))
entities.draw(screen)
enemy_list.draw(screen)
pygame.display.flip() # You need only one flip or update call per frame.
class Entity(pygame.sprite.Sprite): #makes player a sprite
def __init__(self):
pygame.sprite.Sprite.__init__(self) #sets sprite to initiate
class Player_class(Entity): #defines player class
def __init__(self, x, y): #x is the player x coordinate, y is the player y coordinate
Entity.__init__(self) #the player is an entity
self.xvel = 0 #how fast the player is moving left and right
self.yvel = 0 #how fast the player is moving up and down
self.onGround = False #assumes the player is in the air
self.image = pygame.Surface((32,32)) #the player is 32*32 pixels
self.image.fill(pygame.Color("#0000FF")) #makes the player blue
self.rect = pygame.Rect(x, y, 32, 32)
self.x = x
self.y = y
def update(self, up, down, left, right, running, platforms):
if up:
if self.onGround:
self.yvel -= 10 #only jump if player is on the ground
if down:
pass
if running:
self.xvel = 12
if left:
self.xvel = -8
if right:
self.xvel = 8
if not self.onGround:
self.yvel += 0.3 #only accelerate with gravity if in the air
if self.yvel > 100: self.yvel = 100 #terminal velocity = 100
if not(left or right):
self.xvel = 0
self.rect.left += self.xvel #falls or jumps
self.collide(self.xvel, 0, platforms) #creates collisions along the x axis
self.rect.top += self.yvel #creates collisions along the y axis
self.onGround = False; #assumes that the player is in the air
# do y-axis collisions
self.collide(0, self.yvel, platforms)
def collide(self, xvel, yvel, platforms):
for p in platforms:
if pygame.sprite.collide_rect(self, p):
if isinstance(p, Exit_block):
pygame.quit()
sys.exit()
if xvel > 0:
self.rect.right = p.rect.left
if xvel < 0:
self.rect.left = p.rect.right
if yvel > 0:
self.rect.bottom = p.rect.top
self.onGround = True
self.yvel = 0
if yvel < 0:
self.rect.top = p.rect.bottom
class Platform(Entity):
def __init__(self, x, y):
Entity.__init__(self)
self.image = pygame.Surface((32, 32))
self.image.fill(pygame.Color("#FFFFFF"))
self.rect = pygame.Rect(x, y, 32, 32)
class Exit_block(Platform):
def __init__(self, x, y):
Platform.__init__(self, x, y)
self.image.fill(pygame.Color("#FF7700"))#exit block is orange
class Enemy(Entity):
def __init__(self, x, y,player):
pygame.sprite.Sprite.__init__(self)
self.image = pygame.Surface((32, 32))
self.xvel = 0
self.yvel = 0
self.image.fill(pygame.Color("#FF0000")) #Enemy is red
self.rect = pygame.Rect(x, y, 32, 32)
self.player = player
def move(self, speed=5): # chase movement
if self.rect.x > self.player.rect.x: # Movement along x direction
self.xvel = -speed
elif self.rect.x < self.player.rect.x:
self.xvel = speed
if self.rect.y < self.player.rect.y: # Movement along y direction
self.yvel = speed
elif self.rect.y > self.player.rect.y:
self.yvel = -speed
def collide(self, xvel, yvel, platforms):
# Check if the enemy collides with the player.
if self.rect.colliderect(self.player.rect):
pygame.quit()
sys.exit()
for p in platforms:
if pygame.sprite.collide_rect(self, p):
if xvel > 0:
self.rect.right = p.rect.left
if xvel < 0:
self.rect.left = p.rect.right
if yvel > 0:
self.rect.bottom = p.rect.top
if yvel < 0:
self.rect.top = p.rect.bottom
def update(self, platforms):
self.move() # Set the velocity.
self.rect.left += self.xvel
self.collide(self.xvel, 0, platforms) #creates collisions along the x axis
self.rect.top += self.yvel #creates collisions along the y axis
self.collide(0, self.yvel, platforms)
if __name__ == "__main__":
main()
pygame.quit()