Python - Pygame 子弹动作

Question

我正在尝试找到一种方法来获得船的旋转并将其应用到光束上，以便它沿被击中的方向行进。我真的不知道该怎么做，但这里是我的代码：请原谅它的混乱，我把 cmets 放进去让你知道是什么。

import sys, pygame, math, time;
from pygame.locals import *;
spaceship = ('spaceship.png')
mouse_c = ('crosshair.png')
backg = ('background.jpg')
fire_beam = ('beams.png')
pygame.init()
screen = pygame.display.set_mode((800, 600))
bk = pygame.image.load(backg).convert_alpha()
mousec = pygame.image.load(mouse_c).convert_alpha()
space_ship = pygame.image.load(spaceship).convert_alpha()
f_beam = pygame.image.load(fire_beam).convert_alpha()
f_beam = pygame.transform.scale(f_beam, (50, 50))
f_beam_rect = f_beam.get_rect()
clock = pygame.time.Clock()
pygame.mouse.set_visible(False)
space_ship_rect = space_ship.get_rect()
space_ship_rect.centerx = 375
space_ship_rect.centery = 300
speed = 3.5
pressed_down = 0
while True:
    clock.tick(60)
    screen.blit(bk, (0, 0))
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()
        elif event.type == MOUSEBUTTONDOWN and event.button == 3:
            pressed_down = 1
        elif event.type == MOUSEBUTTONUP:
            pressed_down = 0
        if pressed_down == 1:
            x, y = pygame.mouse.get_pos()
            x1, y1 = x - space_ship_rect.x, y - space_ship_rect.y
            angle = math.atan2(y1, x1)
            dx = speed*math.cos(angle)
            dy = speed*math.sin(angle)
            movex = space_ship_rect.centerx = space_ship_rect.centerx + dx#ship x
            movey = space_ship_rect.centery = space_ship_rect.centery + dy#ship y
        if event.type == MOUSEMOTION:
            x1, y1 = pygame.mouse.get_pos()
            x2, y2 = space_ship_rect.x, space_ship_rect.y
            dx, dy = x2 - x1, y2 - y1
            rads = math.atan2(dx, dy)
            degs = math.degrees(rads)
            display_s = pygame.transform.rotate(space_ship, (degs))#rotation of ship
        if event.type == MOUSEBUTTONDOWN and event.button == 1:
            #Is it possible for me to get the degree rotation of the space_ship and apply it to here so the beam will travel in the direction it was shot in?
    screen.blit(display_s, (space_ship_rect.centerx, space_ship_rect.centery))
    pos = pygame.mouse.get_pos()
    screen.blit(mousec, (pos))
    pygame.display.update()

Answer 1

我发现你的船舶旋转有问题。

如果你创建旋转的宇宙飞船display_s，你会得到与space_ship不同大小的图像，所以你必须得到display_s矩形并将宇宙飞船center分配给display_s中心。

 display_s_rect = display_s.get_rect( center=spaceship_rect.center)

现在你必须使用display_s_rect 来显示display_s

 screen.blit(display_s, display_s_rect)

---

顺便说一句：

blit() 期望在屏幕上放置 blited 图像左上角的位置。

有

screen.blit(display_s, (space_ship_rect.centerx, space_ship_rect.centery))

display_s 的左上角将放在(space_ship_rect.centerx, space_ship_rect.centery)，但我想你想把display_s 中心放在(space_ship_rect.centerx, space_ship_rect.centery) 中

将中心值（如前所述）分配给(space_ship_rect.centerx, space_ship_rect.centery)，但在blit() 中使用(space_ship_rect.x, space_ship_rect.y)。

您可以使用space_ship_rect 代替blit() 中的(space_ship_rect.x, space_ship_rect.y)，结果相同。

---

我认为您在blit() 中的mousec 位置也有同样的问题。

获取mousec矩形，将鼠标位置分配给矩形中心，然后使用矩形x，y进行blit。

 mousec_rect = mousec.get_rect( center = pygame.mouse.get_pos() )
 screen.blit(mousec, mousec_rect)

---

编辑：

我修改后你的主循环 - 现在船正在旋转

display_s = space_ship # default value at start when ship wasn't rotate

while True:
    clock.tick(60)
    screen.blit(bk, (0, 0))
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()
        elif event.type == MOUSEBUTTONDOWN and event.button == 3:
            pressed_down = 1
        elif event.type == MOUSEBUTTONUP:
            pressed_down = 0
        if pressed_down == 1:
            x, y = pygame.mouse.get_pos()
            x1, y1 = x - space_ship_rect.x, y - space_ship_rect.y
            angle = math.atan2(y1, x1)
            dx = speed*math.cos(angle)
            dy = speed*math.sin(angle)
            movex = space_ship_rect.centerx = space_ship_rect.centerx + dx#ship x
            movey = space_ship_rect.centery = space_ship_rect.centery + dy#ship y
        if event.type == MOUSEMOTION:
            x1, y1 = pygame.mouse.get_pos()
            x2, y2 = space_ship_rect.centerx, space_ship_rect.centery
            dx, dy = x2 - x1, y2 - y1
            rads = math.atan2(dx, dy)
            degs = math.degrees(rads)

            display_s = pygame.transform.rotate(space_ship, (degs))#rotation of ship
            display_s_rect = display_s.get_rect(center = space_ship_rect.center)            

        if event.type == MOUSEBUTTONDOWN and event.button == 1:
            #Is it possible for me to get the degree rotation of the space_ship and apply it to here so the beam will travel in the direction it was shot in?
            pass

    screen.blit(display_s, display_s_rect)
    #screen.blit(display_s, space_ship_rect)

    pos = pygame.mouse.get_pos()
    mousec_rect = mousec.get_rect(centerx=pos[0], centery=pos[1])

    screen.blit(mousec, mousec_rect )

    pygame.display.update()

Answer 2

在 While 循环之前：
beam_speed=<somevalue>
f_beam_rect=space_ship_rect #initialise beam position
fired=False #check if beam is fired or not

While 循环内部

##If beam is fired(right click) blit images through-out the path
if fired:
    b_angle = math.atan2(by1, bx1)
    bdx = beam_speed*math.cos(b_angle)
    bdy = beam_speed*math.sin(b_angle)
    f_beam_rect.centerx = f_beam_rect.centerx + bdx
    f_beam_rect.centery = f_beam_rect.centery + bdy
    screen.blit(f_beam,f_beam_rect)

for event in pygame.event.get():

    if event.type == QUIT:
        pygame.quit()
        sys.exit()

###If mouse is clicked then find the direction (mouse position and spaceship)

    elif event.type == MOUSEBUTTONDOWN and event.button == 1:
        bx, by = pygame.mouse.get_pos()
        bx1, by1 = bx - space_ship_rect.x, by - space_ship_rect.y
        fired=True

现在您可以创建一个函数来检查光束是否与敌方物体发生碰撞，如果为 True，则停止对光束和该物体进行 blitting。
同时重置变量fired=False 并重置光束位置以再次从宇宙飞船开始f_beam_rect=space_ship_rect