Add Circle.intersect()

[itzpr3d4t0r]

Part of #169. This PR adds the .intersect() method to the Circle class. It returns a list of points of intersection if there are any, or an empty list otherwise. This is inteded to be further expanded to support all geometry shapes (Line and Polygon) as well pygame's Rect and Frect.

This is a ltl test program that demos the functionality:

from geometry import Circle
import pygame

sw, sh = 600, 600
swh, shh = sw / 2, sh / 2
c = Circle((swh, shh), 100)

pygame.init()
screen = pygame.display.set_mode((sw, sh))
clock = pygame.time.Clock()
keep = True

c2 = Circle((swh + 50, shh + 50), 100)

angle = 1

while keep:
    dt = clock.tick_busy_loop(165) / 16

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            keep = False

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

    c2.center = pygame.mouse.get_pos()

    pygame.draw.circle(screen, (255, 255, 255), c.center, c.r, 1)
    pygame.draw.circle(screen, (255, 255, 255), c2.center, c2.r, 1)

    for center in c.intersect(c2):
        pygame.draw.circle(screen, (255, 0, 0), center, 5)

    pygame.display.flip()


pygame.quit()