Add Circle.intersect()

[itzpr3d4t0r]

This PR adds the general purpose Circle.intersect() function. It's a function that finds all intersection points (as long as there's a finite number of them) between the circle and any other shape. Since this is a first implementation it only supports circle-circle intesection but it will support rects/lines/polygons in the future too.

A little demo to test this:

from pygame.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:
    clock.tick_busy_loop(60)

    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()

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


pygame.quit()

Credits

Geometry Project:
For code, docs and tests:
@novialriptide @Emc2356 @itzpr3d4t0r @ScriptLineStudios @avaxar @Matiiss @newpaxonian @maqa41 @blankRiot96
Also thanks to @Starbuck5 for kickstarting the idea and the occasional help!

Functionality added in this PR

• circle.c
  https://github.com/pygame-community/pygame-geometry/blame/main/src_c/circle.c
  Credits to @Emc2356 @itzpr3d4t0r @novialriptide
• geometry.pyi
  https://github.com/pygame-community/pygame-geometry/blame/main/geometry.pyi
  Credits to @Emc2356 @itzpr3d4t0r @novialriptide @ScriptLineStudios @avaxar
• geometry_test.py
  https://github.com/pygame-community/pygame-geometry/blame/main/test/test_circle.py
  Credits to @itzpr3d4t0r @novialriptide
• geometry.rst
  https://github.com/pygame-community/pygame-geometry/blame/main/docs/circle.rst
  Credits to @itzpr3d4t0r
• geometry.h
  https://github.com/pygame-community/pygame-geometry/blame/main/src_c/include/geometry.h
  Credits to @Emc2356 @itzpr3d4t0r @maqa41

[damusss]

Any reason why it doesn't support Rects and FRects (as they exist already)?

[itzpr3d4t0r]

Any reason why it doesn't support Rects and FRects (as they exist already)?

I did a direct port from the geometry repo, which doesn’t have rectangle intersection implemented yet. We agreed to implement features there first to ensure proper code attribution.

[damusss]

I tested locally and the intersection cases worked out great (as expected since this is a direct port), so the PR LGTM. One step closer for Circle to be stable (allowing the other shapes to be ported aswell)

[bilhox]

LGTM !

[ankith26]

LGTM, thanks for the PR 🎉