<p>带有裸<code>except</code>的<code>try</code>是一种反模式,几乎不应该使用,因为它隐藏了<code>try</code>子句中的所有错误,使代码难以调试。我会删除它并重新排列事件处理代码。你知道吗</p>
<p>当按下箭头键时,仅根据该键更改速度向量,而不是创建新的投射实例。然后再次检查是否按了任何箭头键,如果计时器已完成,则创建一个投射物实例并传递当前速度向量。你知道吗</p>
<pre><code>import pygame as pg
from pygame.math import Vector2
BULLET_IMG = pg.Surface((9, 9))
BULLET_IMG.fill(pg.Color('aquamarine2'))
class Projectile(pg.sprite.Sprite):
def __init__(self, pos, vel):
super().__init__()
self.image = BULLET_IMG
self.rect = self.image.get_rect(center=pos)
self.vel = Vector2(vel)
def update(self):
self.rect.move_ip(self.vel)
def main():
pg.init()
screen = pg.display.set_mode((640, 480))
clock = pg.time.Clock()
projectiles = pg.sprite.Group()
previous_time = pg.time.get_ticks()
speed = 12
vel = Vector2(speed, 0)
done = False
while not done:
for event in pg.event.get():
if event.type == pg.QUIT:
done = True
elif event.type == pg.KEYDOWN:
# Only change the velocity vector.
if event.key == pg.K_LEFT:
vel = Vector2(-speed, 0)
elif event.key == pg.K_RIGHT:
vel = Vector2(speed, 0)
elif event.key == pg.K_UP:
vel = Vector2(0, -speed)
elif event.key == pg.K_DOWN:
vel = Vector2(0, speed)
# If an arrow keys was pressed, create a new projectile.
if event.key in (pg.K_LEFT, pg.K_RIGHT, pg.K_UP, pg.K_DOWN):
current_time = pg.time.get_ticks()
# We're ready to fire when 500 ms have passed.
if current_time - previous_time > 500:
previous_time = current_time
# Now create the projectile instance and pass
# the position and the velocity.
projectiles.add(Projectile(pg.mouse.get_pos(), vel))
projectiles.update()
screen.fill((30, 30, 30))
projectiles.draw(screen)
pg.display.update()
clock.tick(60)
if __name__ == '__main__':
main()
pg.quit()
</code></pre>