如何移动鼠标指针并同时指向它？

Question

我是 Pygame 2 的新手（实际上 python 一般而言），我想为学校制作一个小游戏。我使用了 this 中的代码，但是当我按下 SPACE 时，我无法让它向光标移动。我不希望它在 x/y 轴上移动... 这是代码 btw

import sys, pygame, math
from pygame.locals import *
spaceship = ('spaceship.png')
mouse_c = ('cursor.png')
backg = ('background.jpg')
lazer = pygame.mixer.Sound("pew.WAV")
pygame.init()

display_width = 1280
display_height = 720
screen = pygame.display.set_mode((display_width,display_height))
pygame.display.set_caption("Space Survival")

bk = pygame.image.load(backg).convert_alpha()
space_ship = pygame.image.load(spaceship).convert_alpha()
mousec = pygame.image.load(mouse_c).convert_alpha()
clock = pygame.time.Clock()
pygame.mouse.set_visible(False)
Ammo = 20
Fuel = 200

while True:
    for event in pygame.event.get():
    if event.type == QUIT:
        pygame.quit()
        sys.exit()
    elif event.type == MOUSEBUTTONDOWN and event.button == 1 and Ammo <= 20:
        print("Pew")
        pygame.mixer.Sound.play(lazer)
    elif event.type == MOUSEBUTTONDOWN and event.button == 3 and Fuel <= 200:
        print("Boost")

screen.blit(bk, (0, 0))
pos = pygame.mouse.get_pos()
angle = 270-math.atan2(pos[1]-(display_height/2),pos[0]-(display_width/2))*180/math.pi
rotimage = pygame.transform.rotate(space_ship,angle)
rect = rotimage.get_rect(center=((display_width/2),(display_height/2)))
screen.blit(rotimage,rect) #I need space_ship to rotate towards my cursor
screen.blit(mousec, (pos))
pygame.display.update()
clock.tick(60)   #FPS

运行 Pygame 2.0 在 Python 3.8。任何提示将不胜感激:)

Answer 1

写一个函数，“follows2 一个目标：

def FollowMe(pops, fpos, step):
    # [...]

我建议计算space飞船和鼠标之间的距离以及从(fpos)到(pops)的单位方向向量。
距离可以通过计算Euclidean distance. Pygame provides distance_to() for that. Th unit direction vector can be computed by dividing the direction vector by the distance or by normalizing (normalize())方向矢量得到：

target_vector       = pygame.math.Vector2(pops)
follower_vector     = pygame.math.Vector2(fpos)

distance = follower_vector.distance_to(target_vector)
direction_vector = target_vector - follower_vector
if distance > 0:
    direction_vector /= distance

现在您可以定义一个精确的 step_distance 并在精灵的方向移动到随从：

if distance > 0:
    new_follower_vector = follower_vector + direction_vector * step_distance.

定义一个step并保证步长距离不大于step:

step_distance = min(distance, step)

最大步距为

max_step = distance - minimum_distance

放在一起：

def FollowMe(pops, fpos, step):
    target_vector       = pygame.math.Vector2(pops)
    follower_vector     = pygame.math.Vector2(fpos)
    new_follower_vector = pygame.math.Vector2(fpos)

    distance = follower_vector.distance_to(target_vector)
    if distance > 0:
        direction_vector    = (target_vector - follower_vector) / distance
        step_distance       = min(distance, step)
        new_follower_vector = follower_vector + direction_vector * step_distance

    return (new_follower_vector.x, new_follower_vector.y)

另见 How to make smooth movement in pygame。

使用函数使space船向鼠标方向移动，pygame.key.get_pressed()在SPACE时移动船按下。 pygame.key.get_pressed() returns a list with the state of each key. If a key is held down, the state for the key is True, otherwise False. Use pygame.key.get_pressed() 评估按钮的当前状态并获得连续移动：

ship_pos = display_width // 2, display_height // 2

while True:
    # [...]

    keys = pygame.key.get_pressed()
    if keys[pygame.K_SPACE]:
        ship_pos = FollowMe(pos, ship_pos, 3)
    angle = 270-math.atan2(pos[1]-ship_pos[1],pos[0]-ship_pos[0])*180/math.pi
    rotimage = pygame.transform.rotate(space_ship,angle)
    rect = rotimage.get_rect(center=ship_pos)

有关图像的旋转，请参阅 and How do I rotate an image around its center using PyGame?

另见 Rotate towards target or mouse respectivley Move towards target and the answer to the question

不使用任何外部资源（声音和图像）的最小示例：

import sys, pygame, math
from pygame.locals import *
pygame.init()

def FollowMe(pops, fpos, step):
    target_vector       = pygame.math.Vector2(pops)
    follower_vector     = pygame.math.Vector2(fpos)
    new_follower_vector = pygame.math.Vector2(fpos)

    distance = follower_vector.distance_to(target_vector)
    if distance > 0:
        direction_vector    = (target_vector - follower_vector) / distance
        step_distance       = min(distance, step)
        new_follower_vector = follower_vector + direction_vector * step_distance

    return (new_follower_vector.x, new_follower_vector.y) 

display_width = 1280
display_height = 720
screen = pygame.display.set_mode((display_width,display_height))
pygame.display.set_caption("Space Survival")
clock = pygame.time.Clock() 

bk = pygame.Surface(screen.get_size())
space_ship = pygame.Surface((20, 50), pygame.SRCALPHA)
space_ship.fill((0, 255, 0)) 
mousec = pygame.Surface((20, 20), pygame.SRCALPHA)
mousec.fill((255, 0, 0)) 

ship_pos = display_width // 2, display_height // 2

while True:
    clock.tick(60)
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()

    pos = pygame.mouse.get_pos()
    keys = pygame.key.get_pressed()
    if keys[pygame.K_SPACE]:
        ship_pos = FollowMe(pos, ship_pos, 3)
    angle = 270-math.atan2(pos[1]-ship_pos[1],pos[0]-ship_pos[0])*180/math.pi
    rotimage = pygame.transform.rotate(space_ship,angle)
    rect = rotimage.get_rect(center=ship_pos)
    
    screen.blit(bk, (0, 0))
    screen.blit(rotimage,rect)
    screen.blit(mousec, pos)
    pygame.display.update()

如何移动鼠标指针并同时指向它？

How do I move to the mouse pointer and point towards it at the same time?

python

pygame

python-3.x

pygame2