用Pygame画一条抛物线

Question

我想在pygame中画一条抛物线。我制作了一个pixelarray对象并循环通过它来确定一个像素是否在抛物线上。我似乎得到了一个点之间有差距的图像。如何使它成为一条连续的线？

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

WIDTH = 640
HEIGHT = 480

pygame.init()
screen = pygame.display.set_mode((WIDTH, HEIGHT), 0, 32)

pxarray = pygame.PixelArray(screen)

while True:
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()

    screen.fill((0,0,0))

    for y, py in enumerate(pxarray):
        for x, px in enumerate(py):
            if int(x) == (int(y)*int(y)) - 30*int(y) + 450:
                pxarray[y][x] = 0xFFFFFF

    pygame.display.update()

Answer 1

color = 255, 0, 0
first = True
prev_x, prev_y = 0, 0
while True:
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()

    screen.fill((0,0,0))

    for y, py in enumerate(pxarray):
        for x, px in enumerate(py):
            if int(x) == (int(y)*int(y)) - 30*int(y) + 450:
                pxarray[y][x] = 0xFFFFFF

                if first:
                    first = False
                    prev_x, prev_y = x, y
                    continue

                pygame.draw.line(screen, color, (prev_y, prev_x), (y, x))
                prev_x, prev_y = x, y

    first = True
    pygame.display.flip()

Answer 2

您需要将抛物线绘制为一系列线段。您使用的段数将决定它的外观是否平滑，因此如果您计算抛物线x = y ^ 2 + 30y + 450，则计算多个y值的x值并从（x0）绘制线条，y0）到（x1，y1）等等。

如果您没有线条图原语，则需要使用Bresenham's Algorithm之类的内容实现一个。