如何绘制气泡并将它们动画成圆圈

Answer 1

if not bubbles[-1][0] == 0: 就是False，只要鼠标没有松开。因此添加许多线段，每个线段都从bubline_start 开始，到当前鼠标位置结束。
您必须在每一帧中重新绘制场景。 bubbles 是一个气泡列表，每个气泡都有一个点列表。按住鼠标时，将新点添加到列表中的最后一个气泡。按下鼠标时开始一个新气泡，松开鼠标时结束一个气泡。这大大简化了您的代码。

最小的例子

import pygame, random

size = [500, 500]
pygame.init()
display = pygame.display.set_mode(size)
clock = pygame.time.Clock()

pressed = False
bubbles = []
background = [50, 25, 25]

run = True
while run:
    clock.tick(100)
    events = pygame.event.get()
    for event in events:
        if event.type == pygame.QUIT:
            run = False

        elif event.type == pygame.MOUSEBUTTONDOWN:
            start_pos = list(event.pos)
            bubble_color = pygame.Color(0)
            bubble_color.hsla = (random.randrange(0, 360), 100, 50, 100)
            bubbles.append((bubble_color, [start_pos]))
            pressed = True

        elif event.type == pygame.MOUSEMOTION and pressed:
            new_pos = list(event.pos)
            if len(bubbles[-1][1]) > 0 and bubbles[-1][1] != new_pos:  
                bubbles[-1][1].append(new_pos)
            
        elif event.type == pygame.MOUSEBUTTONUP:
            pressed = False
            end_pos = list(event.pos)
            if len(bubbles[-1][1]) > 0 and bubbles[-1][1] != end_pos:  
                bubbles[-1][1].append(list(event.pos))

    display.fill(background)
    for i, bubble in enumerate(bubbles):
        if len(bubble[1]) > 1:
            closed = not pressed or i < len(bubbles) - 1
            pygame.draw.lines(display, bubble[0], closed, bubble[1], 3)
    pygame.display.update()

pygame.quit()

---

对于动画，我建议创建一个代表气泡的类和一个方法animate，它可以慢慢地将多边形变成一个圆。

最小的例子

import pygame, random

size = [500, 500]
pygame.init()
display = pygame.display.set_mode(size)
clock = pygame.time.Clock()

class Bubble:
    def __init__(self, start):
        self.color = pygame.Color(0)
        self.color.hsla = (random.randrange(0, 360), 100, 50, 100)
        self.points = [list(start)]
        self.closed = False
        self.finished = False
    def add_point(self, point, close):
        self.points.append(list(point))
        self.closed = close
        if self.closed:
            x_, y_ = list(zip(*self.points))
            x0, y0, x1, y1 = min(x_), min(y_), max(x_), max(y_)
            rect = pygame.Rect(x0, y0, x1-x0, y1-y0)
            self.center = rect.center
            self.radius = max(*rect.size) // 2
    def animate(self):
        if self.closed and not self.finished:
            cpt = pygame.math.Vector2(self.center) + (0.5, 0.5)
            self.finished = True
            for i, p in enumerate(self.points):
                pt = pygame.math.Vector2(p)
                v = pt - cpt
                l = v.magnitude()
                if l + 0.5 < self.radius:
                    self.finished = False
                v.scale_to_length(min(self.radius, l+0.5))
                pt = cpt + v
                self.points[i] = [pt.x, pt.y]
                
    def draw(self, surf):
        if self.finished:
            pygame.draw.circle(surf, self.color, self.center, self.radius, 3)
        elif len(self.points) > 1:
            pygame.draw.lines(surf, self.color, self.closed, self.points, 3)

bubbles = []
pressed = False
background = [50, 25, 25]

run = True
while run:
    clock.tick(100)
    events = pygame.event.get()
    for event in events:
        if event.type == pygame.QUIT:
            run = False

        elif event.type == pygame.MOUSEBUTTONDOWN:
            bubbles.append(Bubble(event.pos))
            pressed = True

        elif event.type == pygame.MOUSEMOTION and pressed:
            bubbles[-1].add_point(event.pos, False)
            
        elif event.type == pygame.MOUSEBUTTONUP:
            bubbles[-1].add_point(event.pos, True)
            pressed = False

    for bubble in bubbles:
        bubble.animate()

    display.fill(background)
    for bubble in bubbles:
        bubble.draw(display)
    pygame.display.update()

pygame.quit()