如何从屏幕上删除单个 pygame 绘图？

Question

当大圆圈接触小圆圈时，我希望它接触的小圆圈从屏幕上消失。但是，我无法弄清楚你是如何在 pygame 中删除单个绘图的。我该如何解决这个问题？ pygame 有内置这个功能吗？

from pygame import *
import random as rd
import math as m

init()
screen = display.set_mode((800, 600))

p_1_x = 200
p_1_y = 200
p_1_change_x = 0
p_1_change_y = 0

def p_1(x, y):
    player_1 = draw.circle(screen, (0, 0, 0), (x, y), 15)

def pick_up(x, y, xx, yy):
    distance = m.sqrt(m.pow(xx - x, 2) + m.pow(yy - y, 2))
    if distance < 19:
        # I think the code to delete should go here
        pass

dots = []
locations = []

for i in range(5):
    x = rd.randint(100, 700)
    y = rd.randint(100, 500)
    locations.append((x, y))

while True:
    screen.fill((255, 255, 255))
    for events in event.get():
        if events.type == QUIT:
            quit()
        if events.type == KEYDOWN:
            if events.key == K_RIGHT:
                p_1_change_x = 1
            if events.key == K_LEFT:
                p_1_change_x = -1
            if events.key == K_UP:
                p_1_change_y += 1
            if events.key == K_DOWN:
                p_1_change_y -= 1

        if events.type == KEYUP:
            if events.key == K_RIGHT or K_LEFT or K_UP or K_DOWN:
                p_1_change_x = 0
                p_1_change_y = 0

    p_1_x += p_1_change_x
    p_1_y -= p_1_change_y
    for i, locate in enumerate(locations):
        dot = draw.circle(screen, (0, 0, 0), locate, 5)
        dots.append(dot)
        for l in enumerate(locate):
            pick_up(p_1_x, p_1_y, locate[0], locate[1])

    p_1(p_1_x, p_1_y)
    display.update()

Answer 1

您的代码非常混乱且难以维护，首先我为 Balls & Dots 创建了 2 个类。 我通过pygame.Rect.colliderect 检测到碰撞，首先我制作了 2 个矩形，然后我像这样检查碰撞：

def pick_up(ball, dot):
    ball_rect = Rect( ball.x - ball.SIZE , ball.y - ball.SIZE , ball.SIZE*2, ball.SIZE*2)
    dot_rect = Rect( dot.x - dot.SIZE , dot.y - dot.SIZE , dot.SIZE*2, dot.SIZE*2)
    if ball_rect.colliderect(dot_rect): 
        return True
    return False

如果检测到碰撞，我将其从 while 循环中的点数组中删除：

for dot in dots:
    if pick_up(ball, dot): # if dot in range ball
            dots.remove(dot)
    dot.draw()

这是完整的来源：

from pygame import *
import random as rd

SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600
NUMBER_OF_DOTS = 5

class Ball():
    SIZE = 15
    def __init__(self, x, y):
        self.x = x
        self.y = y
        
    def draw(self):
        draw.circle(screen, (0, 0, 0), (self.x, self.y), Ball.SIZE)
    def move(self, vx, vy):
        self.x += vx
        self.y += vy

class Dot():
    SIZE = 5    
    def __init__(self, x, y):
        self.x = x
        self.y = y
        
    def draw(self):
        draw.circle(screen, (0, 0, 0), (self.x, self.y), Dot.SIZE)


def pick_up(ball, dot):
    ball_rect = Rect( ball.x - ball.SIZE , ball.y - ball.SIZE , ball.SIZE*2, ball.SIZE*2)
    dot_rect = Rect( dot.x - dot.SIZE , dot.y - dot.SIZE , dot.SIZE*2, dot.SIZE*2)
    if ball_rect.colliderect(dot_rect): 
        return True
    return False



init()
screen = display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT))

dots = []
ball = Ball(200,200)

# generate dots
for i in range(NUMBER_OF_DOTS):
    x = rd.randint(100, 700)
    y = rd.randint(100, 500)
    dots.append(Dot(x,y))

# the main game loop
while True:
    screen.fill((255, 255, 255))
    keys=key.get_pressed()

    for events in event.get():
        keys=key.get_pressed()
        if events.type == QUIT:
            quit()

    if keys[K_RIGHT]:
        ball.move(+1,0)
    if keys[K_LEFT]:
        ball.move(-1,0)
    if keys[K_UP]:
        ball.move(0,-1)
    if keys[K_DOWN]:
        ball.move(0,+1)

    for dot in dots:
        dot.draw()
        
        if pick_up(ball, dot):
                dots.remove(dot)

    ball.draw()
    display.update()
    time.delay(1) # Speed down

更新1：

PyGame 矩形碰撞 http://www.pygame.org/docs/ref/rect.html#pygame.Rect.colliderect

更新2：

我在 github 上做了一个 repo 并做了一些更改，
点是彩色的，新点的颜色随机，每次吃点球都会变大。

https://github.com/peymanmajidi/Ball-And-Dots-Game__Pygame

Answer 2

代码应该将它从locations 列表中删除，这样以后就不会重新绘制它。您每帧清除屏幕，因此清除+不重绘是“删除”。

假设您修改了pick_up() 以简单地返回 True 或 False：

def pick_up(x, y, xx, yy):
    result = False
    distance = m.sqrt(m.pow(xx - x, 2) + m.pow(yy - y, 2))
    if distance < 19:
        result = True              # It was picked
    return result

然后，当您遍历 locations 列表绘图并检查是否被选中时，保存选中圆圈的索引，然后在第二步中将它们从 locations 中删除。使用两步表单意味着您不必担心在迭代时从列表中删除项目时意外跳过项目。

p_1_x += p_1_change_x
p_1_y -= p_1_change_y
picked_up = []                           # empty list to hold "picked" items
for i, locate in enumerate(locations):
    dot = draw.circle(screen, (0, 0, 0), locate, 5)
    dots.append(dot)
    for l in enumerate(locate):
        if ( pick_up(p_1_x, p_1_y, locate[0], locate[1]) ):
            picked_up.append( i )        # save the index of anything "picked"

# remove any picked-up circles from the list
for index in sorted( picked_up, reverse=True ):   # start with the highest index first
    print( "Removing circle from location[%d]" % ( index ) )  # DEBUG
    del( locations[ index ] )