PYGAME - 用向量移动字符

Question

我正在自学 pygame，并且正在考虑让我的角色能够旋转，然后朝着他们所面对的方向移动。

我可以进行旋转，但无法让角色朝图像所面对的方向移动。

代码在 Trinket HERE

class Bob(pygame.sprite.Sprite):
  def __init__(self, color , height , width):
    super().__init__()
    self.image = pygame.Surface([width , height])
    self.image.fill(BLACK)
    self.image.set_colorkey(BLACK)
    
    #Loading the image for the character
    self.img = pygame.image.load("char.jfif")
    #creating a copy of the image
    self.img_orig = self.img.copy()
    #defining the starting angle of the character image
    self.angle = 0
    
    self.velocity = 5
    self.rect = self.img_orig.get_rect()
    
  def moveLeft(self):
    self.angle += 1
    self.img = pygame.transform.rotate(self.img_orig, self.angle)
      
  def moveRight(self):
    self.rect.x += self.velocity
    if self.rect.x > 485:
      self.rect.x = 485

while run:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False
            
    keys = pygame.key.get_pressed()
    if keys[pygame.K_UP]:
      pSprite.moveForward()
    if keys[pygame.K_DOWN]:
      pSprite.moveDown()
    if keys[pygame.K_LEFT]:
      pSprite.moveLeft()
    if keys[pygame.K_RIGHT]:
      pSprite.moveRight()

    #---- Game Logic Here
    
      
    #--- Drawing Code Here
    #Reset the screen to blank
    screen.fill(BLUE)
    #Draw Play Area
    
    #Draw Sprites
    screen.blit(pSprite.img,(pSprite.rect.x, pSprite.rect.y))

Answer 1

您可以使用 pygame 的 Vector2 类来代替自己计算精灵的位置。

我还建议让精灵自己处理它的运动，而不是在主循环中这样做，并使用时钟来保持恒定的帧速率并轻松控制精灵的速度。

您可能还想使用带 Alpha 通道的图像格式（如 PNG）。

这是一个简单的例子：

import pygame

class Actor(pygame.sprite.Sprite):
    def __init__(self, pos, *grps):
        super().__init__(*grps)
        self.image = pygame.image.load('char.png').convert_alpha()
        self.image_org = self.image.copy()
        self.rect = self.image.get_rect(center=pos)
        self.pos = pygame.Vector2(pos)
        self.direction = pygame.Vector2((0, -1))
        
    def update(self, events, dt):
        pressed = pygame.key.get_pressed()
        
        # if a is pressed, rotate left with 360 degress per second
        if pressed[pygame.K_a]: self.direction.rotate_ip(dt * -360) 
        # if d is pressed, rotate right with 360 degress per second
        if pressed[pygame.K_d]: self.direction.rotate_ip(dt *  360)

        # check if should move forward or backward
        movement = 0
        if pressed[pygame.K_w]: movement =  1
        if pressed[pygame.K_s]: movement = -1
        movement_v = self.direction * movement
        if movement_v.length() > 0:
            movement_v.normalize_ip()
            # move 100px per second in the direction we're facing
            self.pos += movement_v * dt * 100
        
        # rotate the image
        self.image = pygame.transform.rotate(self.image_org, self.direction.angle_to((0, -1)))
        self.rect = self.image.get_rect(center=self.pos)
        

def main():
    pygame.init()
    screen = pygame.display.set_mode((600, 480))
    sprites = pygame.sprite.Group()
    Actor((100, 100), sprites)
    clock, dt = pygame.time.Clock(), 0
    while True:
        events = pygame.event.get()
        for e in events:
            if e.type == pygame.QUIT:
                return
        screen.fill('grey')
        sprites.draw(screen)
        sprites.update(events, dt)
        pygame.display.flip()
        dt = clock.tick(60) / 1000
main()

char.png

Answer 2

围绕其中心旋转播放器（参见How do I rotate an image around its center using PyGame?）：

self.angle += 1
self.img = pygame.transform.rotate(self.img_orig, self.angle)
self.rect = self.img.get_rect(center = self.rect.center)

使用属性x 和y 以浮点精度存储玩家的位置。

class Bob(pygame.sprite.Sprite):
  def __init__(self, color , height , width):
    # [...]

    self.x, self.y = self.rect.center

使用三角函数math.sin 和math.cos 根据角度计算玩家的方向。更改位置属性并更新rect属性：

self.x += self.velocity * math.cos(math.radians(self.angle + 90))
self.y -= self.velocity * math.sin(math.radians(self.angle + 90))
self.rect.center = round(self.x), round(self.y)

y 轴需要反转（-dy），因为 y 轴通常指向上方，但在 PyGame 坐标系中，y 轴指向下方。此外，必须减去校正角（+ 90）。由于精灵向上看的时候“角度”是0°，所以需要在角度加上90°来计算方向向量。

在 pygame 中使用按键移动时另见 te](How to turn the sprite in pygame while moving with the keys.

---

班级Bob:

import pygame
import math
BLACK = (0,0,0)

class Bob(pygame.sprite.Sprite):
  def __init__(self, color , height , width):
    super().__init__()
    self.image = pygame.Surface([width , height])
    self.image.fill(BLACK)
    self.image.set_colorkey(BLACK)
    
    #Loading the image for the character
    self.img = pygame.image.load("char.jfif")
    #creating a copy of the image
    self.img_orig = self.img.copy()
    #defining the starting angle of the character image
    self.angle = 0
    
    self.velocity = 5
    self.rect = self.img_orig.get_rect()
    self.x, self.y = self.rect.center
    
  def rotate(self, change_angle):
    self.angle += change_angle
    self.img = pygame.transform.rotate(self.img_orig, self.angle)
    self.rect = self.img.get_rect(center = self.rect.center)
    
  def move(self, distance):
    self.x += distance * math.cos(math.radians(self.angle + 90))
    self.y -= distance * math.sin(math.radians(self.angle + 90))
    self.rect.center = round(self.x), round(self.y)
    
  def moveLeft(self):
    self.rotate(1) 
  def moveRight(self):
    self.rotate(-1)
    
  def moveForward(self):
    self.move(self.velocity)
  def moveDown(self):
    self.move(-self.velocity)

---

设置播放器起始位置时，需要设置x、y和rect属性：

pSprite = Bob(WHITE , 25,25)
pSprite.rect.x = 50
pSprite.rect.y = 50
pSprite.x, pSprite.y = pSprite.rect.center