问题
I've been working on this project about tanks (based on game Tank Trouble) and I'm wondering how I can move forward after I change angle of the sprite. Also if you know how I can make my bullets ricochet from the walls. I will really appreciate any help given. Thank you!
Here is my tank and bullet:
Here is code of the game:
import sys
import pygame
class Game:
def __init__(self):
self.run = True
self.screen_width = 1060
self.screen_height = 798
self.image = pygame.image.load("sprites/background/background1.png")
self.image = pygame.transform.scale(self.image, (self.screen_width, self.screen_height))
self.screen = pygame.display.set_mode((self.screen_width, self.screen_height))
# all_sprites is used to update and draw all sprites together.
self.all_sprites = pygame.sprite.Group()
# for collision detection with enemies.
self.bullet_group = pygame.sprite.Group()
self.tank = Tank()
self.all_sprites.add(self.tank)
bullet = Bullet(self.tank)
self.bullet_group.add(bullet)
self.all_sprites.add(bullet)
def handle_events(self):
keys = pygame.key.get_pressed()
self.tank.handle_events()
if keys[pygame.K_UP]:
self.tank.rect.centery -= 5
if keys[pygame.K_DOWN]:
self.tank.rect.centery += 5
for event in pygame.event.get():
if event.type == pygame.QUIT:
self.run = False
elif event.type == pygame.KEYDOWN:
if event.key == pygame.K_ESCAPE:
self.run = False
if event.key == pygame.K_SPACE:
bullet = Bullet(self.tank)
self.bullet_group.add(bullet)
self.all_sprites.add(bullet)
def update(self):
# Calls `update` methods of all contained sprites.
self.all_sprites.update()
def draw(self):
self.screen.blit(self.image, (0, 0))
self.all_sprites.draw(self.screen) # Draw the contained sprites.
pygame.display.update()
class Tank(pygame.sprite.Sprite):
def __init__(self):
pygame.sprite.Sprite.__init__(self)
self.image = pygame.image.load("sprites/player/player_tank.png")
self.org_image = self.image.copy()
# A nicer way to set the start pos with `get_rect`.
self.rect = self.image.get_rect(center=(70, 600))
self.angle = 0
self.direction = pygame.Vector2(1, 0)
self.pos = pygame.Vector2(self.rect.center)
def handle_events(self):
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 Bullet(pygame.sprite.Sprite):
def __init__(self, tank):
pygame.sprite.Sprite.__init__(self)
self.image = pygame.image.load("sprites/bullet/bullet.png")
self.image = pygame.transform.scale(self.image, (16, 16))
self.rect = self.image.get_rect()
self.rect.centerx = tank.rect.centerx + 3 # How much pixels from tank turret on x axis
self.rect.centery = tank.rect.centery - 25 # How much pixels from tank turret on y axis
def update(self):
self.rect.y -= 10 # Move up 10 pixels per frame.
def main():
pygame.init()
pygame.display.set_caption('Tank Game')
clock = pygame.time.Clock()
game = Game()
while game.run:
game.handle_events()
game.update()
game.draw()
clock.tick(60)
if __name__ == '__main__':
main()
pygame.quit()
sys.exit()
回答1:
To move the tank in the direction which is faced, wirte a method, that computes a direction vector, dependent on an velocity argument and the self.angle attribute. The nagle and the velocity define a vector by Polar coordinats.
Add the vector to it's current position (self.pos). Finally update the self.rect attribute by the position:
class Tank(pygame.sprite.Sprite):
# [...]
def move(self, velocity):
direction = pygame.Vector2(0, velocity).rotate(-self.angle)
self.pos += direction
self.rect.center = round(self.pos[0]), round(self.pos[1])
Invoke the method when up or down is pressed:
class Game:
# [...]
def handle_events(self):
# [...]
if keys[pygame.K_UP]:
self.tank.move(-5)
if keys[pygame.K_DOWN]:
self.tank.move(5)
The movement direction of the bullets can be computed similar:
class Bullet(pygame.sprite.Sprite):
def __init__(self, tank):
#[...]
self.rect = self.image.get_rect()
self.angle = tank.angle
self.pos = pygame.Vector2(tank.pos)
self.rect.center = round(self.pos.x), round(self.pos.y)
self.direction = pygame.Vector2(0, -10).rotate(-self.angle)
def update(self):
self.pos += self.direction
self.rect.center = round(self.pos[0]), round(self.pos[1])
To make the bullet bounce, you have to reflect the direction when the bullet hits a border:
class Bullet(pygame.sprite.Sprite):
# [...]
def update(self):
self.pos += self.direction
self.rect.center = round(self.pos.x), round(self.pos.y)
if self.rect.left < 0:
self.direction.x *= -1
self.rect.left = 0
self.pos.x = self.rect.centerx
if self.rect.right > 1060:
self.direction.x *= -1
self.rect.right = 1060
self.pos.x = self.rect.centerx
if self.rect.top < 0:
self.direction.y *= -1
self.rect.top = 0
self.pos.y = self.rect.centery
if self.rect.bottom > 798:
self.direction.y *= -1
self.rect.right = 798
self.pos.y = self.rect.centery
来源：https://stackoverflow.com/questions/61106297/moving-forward-after-angle-change-pygame