python - 如何在Pygame中以小角度低速并闪烁的方式绘制移动圆圈？

Question

下面的代码在屏幕上移动两个球。第一个以 10 度的角度低速移动，具有良好的绘图质量。第二个球以 1 度的角度移动，为了尊重该角度，速度必须高得多，并且眨眼很多，绘图不令人满意。有没有办法减慢第二个球的绘制速度并避免过度闪烁？

import pygame, sys, math
from pygame.locals import *

pygame.init()
DISPLAYSURF = pygame.display.set_mode((1000, 600))
pygame.display.set_caption('Bouncing Ball with position and angle')

# Set our color constants
BLACK = (0, 0, 0)
YELLOW = (255, 255, 0)

# Create the ball class
class Ball():
    def __init__(self,
                 screen,
                 color,
                 radius,
                 startX,
                 startY,
                 speed,
                 angle=45):
        super().__init__()
        self.screen = screen
        self.color = color
        rectSize = radius * 2
        self.rect = pygame.Rect(startX, startY, rectSize, rectSize)
        self.speed = speed
        self.angle = math.radians(angle)

    def update(self):
        delta_x = self.speed * math.cos(self.angle)
        delta_y = self.speed * math.sin(self.angle)
        self.rect = self.rect.move(delta_x, delta_y)

        if self.rect.right >= self.screen.get_width() or self.rect.left <= 0:
            self.angle = math.pi - self.angle

        if self.rect.top <= 0 or self.rect.bottom >= self.screen.get_height():
            self.angle = -self.angle

    def draw(self):
        '''
        Draw our ball to the screen with position information.
        '''
        pygame.draw.circle(self.screen, self.color, self.rect.center, int(self.rect.width / 2))

# Create a new Ball instance named 'myball'
myball = Ball(screen=DISPLAYSURF, color=YELLOW, startX=100, startY=100, radius=150, speed=8, angle=10)
mySmaLlAngleball = Ball(screen=DISPLAYSURF, color=YELLOW, startX=100, startY=500, radius=150, speed=58, angle=-1)

run = True
clock = pygame.time.Clock()

# Display loop
while run:
    # Handle events
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()

    # Update ball position
    myball.update()
    mySmaLlAngleball.update()

    # Draw screen
    DISPLAYSURF.fill(BLACK)
    myball.draw()
    mySmaLlAngleball.draw()
    pygame.display.update()
    clock.tick(30)

Answer 1

问题是造成的，因为 pygame.Rect 存储积分坐标:

The coordinates for Rect objects are all integers. [...]

delta_x的分数分量和 delta_y丢失于 self.rect.move(delta_x, delta_y) .
您必须使用浮点数进行计算。添加属性 self.pos ，这是一个包含 2 个组件的 tupe，用于存储球的中心点:

self.pos = self.rect.center

计算具有最大浮点精度的位置:

delta_x = self.speed * math.cos(self.angle)
delta_y = self.speed * math.sin(self.angle)
self.pos = (self.pos[0] + delta_x, self.pos[1] + delta_y)   

更新 self.rect.center由 round() ed位置。

self.rect.center = round(self.pos[0]), round(self.pos[1])

self.pos是“内部”位置，负责位置的精确计算。 self.rect.center是积分位置，负责拉球。 self.pos每帧略有变化。 self.rect.center只有当坐标的 a 分量改变了 1 时才会改变。
类(class) Ball :

class Ball():
    def __init__(self,
                 screen,
                 color,
                 radius,
                 startX,
                 startY,
                 speed,
                 angle=45):
        super().__init__()
        self.screen = screen
        self.color = color
        rectSize = radius * 2
        self.rect = pygame.Rect(startX, startY, rectSize, rectSize)
        self.speed = speed
        self.angle = math.radians(angle)
        self.pos = self.rect.center

    def update(self):
        delta_x = self.speed * math.cos(self.angle)
        delta_y = self.speed * math.sin(self.angle)
        self.pos = (self.pos[0] + delta_x, self.pos[1] + delta_y)

        self.rect.center = round(self.pos[0]), round(self.pos[1])

        if self.rect.right >= self.screen.get_width() or self.rect.left <= 0:
            self.angle = math.pi - self.angle

        if self.rect.top <= 0 or self.rect.bottom >= self.screen.get_height():
            self.angle = -self.angle

    def draw(self):
        '''
        Draw our ball to the screen with position information.
        '''
        pygame.draw.circle(self.screen, self.color, self.rect.center, int(self.rect.width / 2))

使用此解决方案，您可以按比例增加每秒的触发器 ( clock.tick() ) 并按相同比例降低速度。这会导致平滑移动而不会眨眼。