如何在pygame中使圆从一个角到另一个角对角移动

如何解决如何在pygame中使圆从一个角到另一个角对角移动

我创建了一个程序来为形状设置动画，我只移动了 x 轴或 y 轴，从来没有同时移动过这两个轴。所以对角移动对我来说是全新的。下面是我的代码：

"""
    Author: Victor Xu

    Date: January 20th,2021

    Description: Animating Shapes with pygame
"""

"""
    1. Modify the animation of the red_Box so that when it hits 
       the left or right side of the window it changes direction. (COMPLETED)

    2. Add a green_rect (40x20) Surface that moves in up and down.
       It should change its y direction when it hits to top or bottom 
       of the window. (COMPLETED)

    3. Add a blue_circle (24x24) Surface that moves in a diagonal path.
       If it hits the top or bottom of the window reverse its 
       y direction,and if it hits the left or right of the window
       reverse its x direction.
"""

import pygame


def main():
    '''This function defines the 'mainline logic' for our game.'''
    # I - INITIALIZE
    pygame.init()

    # disPLAY
    screen = pygame.display.set_mode((640,480))
    pygame.display.set_caption("Crazy Shapes Animation")

    # ENTITIES
    background = pygame.Surface(screen.get_size())
    background = background.convert()
    background.fill((255,255,255))  # white background

    # Make a red 25 x 25 Box
    red_Box = pygame.Surface((25,25))
    red_Box = red_Box.convert()
    red_Box.fill((255,0))

    # Make a green 40 x 20 rectangle
    green_rect = pygame.Surface((40,20))
    green_rect = green_rect.convert()
    green_rect.fill((0,0))

    # Make a blue 24 x 24 circle
    blue_circ = pygame.Surface((24,24))
    blue_circ = blue_circ.convert()
    blue_circ.fill((0,255))
    pygame.draw.circle(blue_circ,(0,255),(25,25),24)

    # A - ACTION (broken into ALTER steps)

    # ASSIGN
    clock = pygame.time.Clock()
    keepGoing = True

    red_Box_x = 0  # Assign starting (x,y)
    red_Box_y = 200  # for our red Box
    move_red_x = 5

    green_rect_x = 300  # Assign starting (x,y)
    green_rect_y = 200  # for our green rectangle
    move_rect_y = 5

    blue_circ_x = 640  # Assign starting (x,y)
    blue_circ_y = 0  # for our blue circle
    move_circ_x = 5
    move_circ_y = 5

    # LOOP
    while keepGoing:

        # TIMER
        clock.tick(30)

        # EVENT HANDLING
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                keepGoing = False

        # change x coordinate of red Box
        red_Box_x += move_red_x
        # check boundaries,to bounce off wall
        if red_Box_x >= screen.get_width():
            red_Box_x = screen.get_width()
            move_red_x *= -1
        if red_Box_x <= 0:
            red_Box_x = 0
            move_red_x *= -1

        # change y coordinate of green rectangle
        green_rect_y += move_rect_y
        # check boundaries,to bounce off wall
        if green_rect_y >= screen.get_height():
            green_rect_y = screen.get_height()
            move_rect_y *= -1
        if green_rect_y <= 0:
            green_rect_y = 0
            move_rect_y *= -1

        # REFRESH (update window)
        screen.blit(background,0))
        screen.blit(green_rect,(green_rect_x,green_rect_y))  # blit rectangle at new (x,y) location
        screen.blit(red_Box,(red_Box_x,red_Box_y))  # blit Box at new (x,y) location
        pygame.display.flip()

    # Close the game window
    pygame.quit()


# Call the main function
main()

如果你能用我的风格完成它就太好了，这样我就能更好地理解它。非常感谢！

解决方法

我将提供一个更通用的方法。定义对象在途中应访问的位置列表 (circle_pos_list)。设置起始位置（circle_pos）、速度（circle_speed）和列表中下一个目标位置的索引（next_pos_index）。

circle_pos_list = [(100,100),(200,150),(100,150)]
circle_pos = circle_pos_list[0]
circle_speed = 5
next_pos_index = 1

使用pygame.math.Vector2计算当前圆到列表中下一个目标位置的距离向量：

circle_dir = pygame.math.Vector2(circle_pos_list[next_pos_index]) - circle_pos

如果到目标的距离小于圆的速度，则踩到目标并将目标位置索引改为下一个目标：

if circle_dir.length() < circle_speed:
    circle_pos = circle_pos_list[next_pos_index]
    next_pos_index = (next_pos_index + 1) % len(circle_pos_list)

否则，沿着向量一步到下一个目的地：

circle_dir.scale_to_length(circle_speed)
new_pos = pygame.math.Vector2(circle_pos) + circle_dir
circle_pos = (new_pos.x,new_pos.y)

代码中的更改：

def main():
    # [...]

    blue_circ = pygame.Surface((24,24))
    blue_circ.set_colorkey((0,0))
    pygame.draw.circle(blue_circ,(0,255),(12,12),12)

    # [...]

    circle_pos_list = [(100,150)]
    circle_pos = circle_pos_list[0]
    circle_speed = 5
    next_pos_index = 1

    # LOOP
    while keepGoing:
        # [...]

        circle_dir = pygame.math.Vector2(circle_pos_list[next_pos_index]) - circle_pos
        if circle_dir.length() < circle_speed:
            circle_pos = circle_pos_list[next_pos_index]
            next_pos_index = (next_pos_index + 1) % len(circle_pos_list)
        else:
            circle_dir.scale_to_length(circle_speed)
            new_pos = pygame.math.Vector2(circle_pos) + circle_dir
            circle_pos = (new_pos.x,new_pos.y)

        # [...]

        screen.blit(blue_circ,(round(circle_pos[0]),round(circle_pos[1])))

        # [...]