如何在Pygame和Pymunk中持续更新圆的半径

Question

我在 Pygame 和 Pymunk 中做了一个简单的测试场景，它只是将一个有弹性的球扔到线上，我希望每次发生碰撞时它都会变大。

import pygame, sys, pymunk


pygame.init()
screen = pygame.display.set_mode((800, 800))
clock = pygame.time.Clock()
space = pymunk.Space()
space.gravity = (0, 500)


#Varibales
CircleRadius = 10



# create ball
BallBody = pymunk.Body(1, 100, body_type=pymunk.Body.DYNAMIC)
BallBody.position = 400, 400

BallShape = pymunk.Circle(BallBody, CircleRadius)
BallShape.elasticity = 0.9
BallShape.collision_type = 1
space.add(BallBody, BallShape)

# Create Container
SegmentBody = pymunk.Body(body_type=pymunk.Body.STATIC)

SegmentShape = pymunk.Segment(SegmentBody, (200, 600), (600, 600), 10)
SegmentShape.elasticity = 1
SegmentShape.collision_type = 2
space.add(SegmentBody, SegmentShape)

#handle collisions
def Collision(arbiter, space, data):
    print("Collision")
    global CircleRadius
    CircleRadius += 2


handler = space.add_collision_handler(1, 2)
handler.separate = Collision

#main game loop
while True:

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()
    screen.fill((0, 0, 0))
    #draw bodys in pygame
    Bx, By = BallBody.position
    pygame.draw.circle(screen, (255, 0, 0), (int(Bx), int(By)), CircleRadius)

    Sx, Sy = SegmentBody.position
    pygame.draw.line(screen, (255, 0, 0), (200, 600), (600, 600), 10)
    space.step(1 / 50)

    pygame.display.update()
    clock.tick(120)

问题是，每次发生碰撞时，Pygame 的视觉效果都会变大，但实际的 Pymunk 物理主体却不会变大。

我尝试过使用ChatGPT，但没有任何效果，我也无法在网上找到任何答案。

Answer 1

您必须创建一个新的

pymunk.Segment

，然后用新段替换旧段：

def Collision(arbiter, space, data):
    print("Collision")
    global CircleRadius, SegmentShape
    CircleRadius += 2
    space.remove(SegmentShape)
    SegmentShape = pymunk.Segment(SegmentBody, (200, 600), (600, 600), CircleRadius)
    SegmentShape.elasticity = 1
    SegmentShape.collision_type = 2
    space.add(SegmentShape)