pythonによる円と線分の交差判定テスト

circle_line_intersection.py

# -*- coding: utf-8 -*-
import pygame
import sys
import random
import shapely.geometry as sg


class Pos:
    def __init__(self, x, y):
        self.x = x
        self.y = y

    def __add__(self, other):
        return Pos(self.x + other.x, self.y + other.y)

    def __sub__(self, other):
        return Pos(self.x - other.x, self.y - other.y)

    def __mul__(self, other):
        return Pos(self.x * other.x, self.y * other.y)

    def norm(self):
        return Pos(self.y, -self.x)

    def pos(self):
        return (self.x, self.y)


class Line:
    def __init__(self, p1, p2):
        self.p1 = p1
        self.p2 = p2

        self.color = (255, 255, 255)

        self.sg_line = sg.LineString([p1.pos(), p2.pos()])

    def draw(self, canvas, screen):
        canvas.line(screen, self.color, self.p1.pos(), self.p2.pos())


class Circle:
    def __init__(self, center, r):
        self.center = center
        self.r = r

        self.color = (255, 255, 255)
        self.sg_circle = sg.Point(center.x, center.y).buffer(r).boundary

    def intersection(self, line):
        points = self.sg_circle.intersection(line.sg_line)
        if isinstance(points, sg.Point):
            return [points.coords[0]]
        return [
            geom.coords[0] for geom in self.sg_circle.intersection(line.sg_line).geoms
        ]

    def draw(self, canvas, screen):
        canvas.circle(screen, self.color, self.center.pos(), self.r, 1)


WID = 800
HEI = 800

def draw(pos_list):
    (w, h) = (WID, HEI)
    (x, y) = (w//2, h//2)
    pygame.init()
    pygame.display.set_mode((w, h), 0, 32)
    screen = pygame.display.get_surface()
    turn = 0
    circle = Circle(Pos(WID // 2, HEI // 2), 100)

    while True:
        pygame.display.update()
        pygame.time.wait(30)
        screen.fill((0, 20, 0, 0))
        circle.draw(pygame.draw, screen)
        if turn < len(pos_list):
            pos_list[turn].draw(pygame.draw, screen)
            for pos in circle.intersection(pos_list[turn]):
                pygame.draw.circle(screen, (0, 255, 255), (int(pos[0]), int(pos[1])), 5)

        pressed = pygame.key.get_pressed()
        if pressed[pygame.K_LEFT] and turn > 0:
            turn -= 1
        if pressed[pygame.K_RIGHT] and turn < len(pos_list)-1:
            turn += 1

        for event in pygame.event.get():
            if is_exit(event):
                pygame.quit()
                return


def is_exit(event):
    return (
        event.type == pygame.KEYDOWN and
        event.key == pygame.K_ESCAPE or
        event.type == pygame.QUIT
    )


def create_pos_list():
    pos_n = 100
    pos_list = []
    for i in range(pos_n):
        x1 = random.random() * 300 + 100
        y1 = random.random() * 300 + 100
        x2 = random.random() * 300 + 300
        y2 = random.random() * 300 + 300
        pos_list.append(Line(Pos(x1, y1), Pos(x2, y2)))
    return pos_list


if __name__ == '__main__':
    pos_list = create_pos_list()
    draw(pos_list)