Pygame tutorial - tank with collision detection

Question

I'm new to Pygame and trying to learn about sprites and collision detection. I found some code and tried to add some functionality to it.

The basic idea is that I have a polygon which can be rotated in place. When the user presses SPACEBAR, the polygon fires a projectile which can bounce around the frame. If the projectile hits the polygon again, I would like to quite the program

First of all, here is the code

import pygame

class Player(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()
        self.image = pygame.Surface((32, 32))
        self.image.fill((0, 0, 0))
        self.image.set_colorkey((0, 0, 0))
        self.fire_from = (36, 20)
        pygame.draw.polygon(self.image, pygame.Color('dodgerblue'), ((0, 0), (32, 16), (0, 32)))
        self.org_image = self.image.copy()
        self.angle = 0
        self.direction = pygame.Vector2(1, 0)
        self.rect = self.image.get_rect(center=(200, 200))
        self.pos = pygame.Vector2(self.rect.center)

    def update(self, events, dt):

        for e in events:
            if e.type == pygame.KEYDOWN:
                if e.key == pygame.K_SPACE:
                    bullet = Projectile(self.fire_from, self.direction.normalize())
                    self.groups()[0].add(bullet)
        pressed = pygame.key.get_pressed()

        if pressed[pygame.K_LEFT]:
            self.angle += 3
        if pressed[pygame.K_RIGHT]:
            self.angle -= 3

        self.direction = pygame.Vector2(1, 0).rotate(-self.angle)
        self.image = pygame.transform.rotate(self.org_image, self.angle)
        self.rect = self.image.get_rect(center=self.rect.center)

class Projectile(pygame.sprite.Sprite):
    def __init__(self, pos, direction):
        super().__init__()
        self.image = pygame.Surface((8, 8))
        self.image.fill((0, 0, 0))
        self.image.set_colorkey((0, 0, 0))
        pygame.draw.circle(self.image, pygame.Color('orange'), (4, 4), 4)
        self.rect = self.image.get_rect(center=pos)
        self.direction = direction
        self.pos = pygame.Vector2(self.rect.center)
        self.max_bounce = 10

    def update(self, events, dt):

        #print(self.pos)
        # Bounding box of the screen
        screen_r = pygame.display.get_surface().get_rect()

        # where we would move next
        next_pos = self.pos + self.direction * dt

        # we hit a wall
        if not screen_r.contains(self.rect):

            # after 10 hits, destroy self
            self.max_bounce -= 1
            if self.max_bounce == 0:
                return self.kill()

            # horizontal reflection
            if next_pos.x > screen_r.right or next_pos.x < screen_r.left:
                self.direction.x *= -1

            # vertical reflection
            if next_pos.y > screen_r.bottom or next_pos.y < screen_r.top:
                self.direction.y *= -1

            # move after applying reflection
            next_pos = self.pos + self.direction * dt

        # set the new position
        self.pos = next_pos
        self.rect.center = self.pos

def main():
    pygame.init()
    screen = pygame.display.set_mode((500, 500))
    tank = Player()
    sprites = pygame.sprite.Group()
    sprites.add(tank)
    #print(tank.groups()[0])
    clock = pygame.time.Clock()
    dt = 0
    running = True
    while running:
        #print(tank.groups()[0])
        events = pygame.event.get()
        for e in events:
            if e.type == pygame.QUIT:
                return
        sprites.update(events, dt)
        screen.fill((30, 30, 30))
        sprites.draw(screen)
        pygame.display.update()

        ## ALWAYS DETECTS A COLLISION, WHY?
        if len(tank.groups()[0])>1:
            if pygame.sprite.spritecollideany(tank, tank.groups()[0]):
                running = False

        dt = clock.tick(60)

if __name__ == '__main__':
    main()

I gather here that the Player class (i.e. my tank) itself has a sprite groups, to which it adds each projectile as its fired. Furthermore, the projectile originates from within the rectangle for the polygon (hence it always initially collides)

I would like to only add the projectile to the sprite group if it has made at least 1 bounce, is that possible? Or... is there a better way to do this?

Any help or pointers please?

Thanks Null

Answer 1

The tank collides with itself, because it is a member of tank.groups()[0]:

if pygame.sprite.spritecollideany(tank, tank.groups()[0]):

Add a Group that contains just the bullets:

class Player(pygame.sprite.Sprite):
    def __init__(self):
        # [...]

        self.bullets = pygame.sprite.Group()

    def update(self, events, dt):

        for e in events:
            if e.type == pygame.KEYDOWN:
                if e.key == pygame.K_SPACE:
                    bullet = Projectile(self.fire_from, self.direction.normalize())
                    self.groups()[0].add(bullet)
                    self.bullets.add(bullet)

        # [...]

Use this Group for the collision test:

def main():
    # [...]

    while running:
        # [...]

        pygame.display.update()

        if pygame.sprite.spritecollideany(tank, tank.bullets):
            running = False

        dt = clock.tick(60)