Pygame：使精灵沿预定路径以恒定速度移动

Question

我正在 Pygame 中开发一款塔防游戏，其中敌人沿着我为他们设置的路径向基地前进；如果你玩过 VR Defender Y3K 和 Canyon Defense 等 Flash 游戏，我的想法是完全相同的概念。但是，我无法让精灵沿着涉及方向变化的路径移动，例如向左或向右转的路径。

所以我的问题是什么是让精灵沿着预定路径以恒定速度改变方向的简单方法？

编辑：这是我到目前为止的代码。

#Project 2 v1.00
import pygame, sys, time
from math import *
from pygame.locals import *

WHITE = (255, 255, 255)
BLACK = (0, 0, 0)
BLUE = (0, 255, 0)
RED = (255, 0, 0)
GREEN = (0, 255, 0)

surface = pygame.display.set_mode((500,500),0, 30)

class PlaceHolder:
    def __init__(self, win, left, top, width, height, color):
        self.win = win
        self.rect = pygame.Rect(left, top, width, height)
        self.color = color

    def move(self,x,y,duration):
        #self.rect = self.rect.move(self.velocity[0],self.velocity[1])
        xpointlist = [60, 60]
        ypointlist = [236, 136]
        self.rect.left += x
        self.rect.top += y
        self.duration = duration
        counter = 0
        rate = 10
        for counter in range(len(xpointlist)-1):
            dx = x - xpointlist[counter]
            dy = y - ypointlist[counter]
            distance = sqrt(dx*dx + dy*dy)
            return distance
        duration = distance/rate

    def draw(self):
        pygame.draw.ellipse(surface, self.color, self.rect, 0)

class projectWin:
    def __init__(self, width, height, caption):
        self.caption = caption
        pygame.display.set_caption(self.caption)
        self.width = width
        self.height = height
        self.placeHolders = []
        self.placeHolders.append(PlaceHolder(surface, 1, 236, 10, 10, GREEN))
        #placeHolder1 = PlaceHolder(surface, 10, 236, 10, 10, GREEN)

    def grid(self):
        for i in range(24, 499, 25): #draw the vertical lines
            pygame.draw.line(surface, WHITE, (i, 0), (i, 499), 1)
        for j in range(24, 499, 25): #draw the horizontal lines
        pygame.draw.line(surface, WHITE, (0, j), (499, j), 1)

    def path(self):
        #the two lines are separated for ease of change
        #line 1
        pygame.draw.line(surface, GREEN, (0, 224), (49, 224), 2)
        pygame.draw.line(surface, GREEN, (49, 224), (49, 149), 2)
        pygame.draw.line(surface, GREEN, (49, 149), (349, 149), 2)
        pygame.draw.line(surface, GREEN, (349, 149), (349, 274), 2)
        pygame.draw.line(surface, GREEN, (349, 274), (99, 274), 2)
        pygame.draw.line(surface, GREEN, (99, 274), (99, 349), 2)
        pygame.draw.line(surface, GREEN, (99, 349), (374, 349), 2)
        pygame.draw.line(surface, GREEN, (374, 349), (374, 224), 2)
        pygame.draw.line(surface, GREEN, (374, 224), (499, 224), 2)

        #line 2
        pygame.draw.line(surface, GREEN, (0, 249), (74, 249), 2)
        pygame.draw.line(surface, GREEN, (74, 249), (74, 174), 2)
        pygame.draw.line(surface, GREEN, (74, 174), (324, 174), 2)
        pygame.draw.line(surface, GREEN, (324, 174), (324, 249), 2)
        pygame.draw.line(surface, GREEN, (324, 249), (75, 249), 2)
        pygame.draw.line(surface, GREEN, (74, 249), (74, 374), 2)
        pygame.draw.line(surface, GREEN, (74, 374), (399, 374), 2)
        pygame.draw.line(surface, GREEN, (399, 374), (399, 249), 2)
        pygame.draw.line(surface, GREEN, (399, 249), (499, 249), 2)

    def base(self): #what the player has to protect
        base = pygame.Rect(474, 187, 99, 99)
        pygame.draw.ellipse(surface, BLUE, base, 0)

pygame.init()

win = projectWin(500, 500, 'Project 2 v1.00')
Quit = False
while not Quit:
    surface.fill(BLACK)
    #draw the grid, path, and base on the screen
    win.grid()
    win.path()
    win.base()
    for i in win.placeHolders: #draw and move the placeholder enemy assets
        i.move(59, 0, duration)
        i.move(0, -100, duration)
        i.draw()
    pygame.display.update()
    time.sleep(0.02)
    for event in pygame.event.get():
        if event.type == QUIT:
            Quit = True

pygame.quit() #always exit cleanly
sys.exit()

Answer 1

如果你提供一些代码，我可以更好地回答，但我可以给你一些见解：

在您尝试制作的游戏中，您可以制作以下内容：

xdirection = 1
ydirection = 1

您可以将方向乘以它们在控制精灵的方向上应该行进的数量。你希望他们走得越快，方向数字就应该越大。您可以使用正面和负面来控制他们将要走的路。

同样，此响应完全是推测性的，因为您没有显示任何代码。如果这没有帮助，请告诉我，我会尝试相应地更改我的回复。