[PyGame] Keeping the player within a polygon

[Atekka]

Hi, I'm trying to implement a polygonal boundary to stop the player from leaving the polygon. The player uses a circular collider. I've looked around online and haven't found anything that really helps. Below is a simple example of what I've got so far. If anyone can help explain an algorithm or at least provide a link to something that might help I would greatly appreciate it.

"""Circle with a polygonal boundary"""
import pygame as pg

pg.init()

display = pg.display.set_mode((1024, 768))

edge_poly = [(10, 10), (400, 10), (350, 300), (150, 400)]
player_pos = pg.Vector2(100, 50)
player_radius = 15
player_speed = .2

running = True
while running:
    # events
    for event in pg.event.get ():
        if event.type == pg.QUIT:
            running = False

    keys_down = pg.key.get_pressed()
    if keys_down[pg.K_w]:
        player_pos.y -= player_speed
    if keys_down[pg.K_s]:
        player_pos.y += player_speed
    if keys_down[pg.K_a]:
        player_pos.x -= player_speed
    if keys_down[pg.K_d]:
        player_pos.x += player_speed
    # updates

    # drawing
    display.fill((255, 255, 255))
    pg.draw.polygon(display, (0, 0, 0), edge_poly, 1)
    pg.draw.circle(display, (0, 0, 0), player_pos, player_radius)
    pg.display.update()

pg.quit()
quit()

Again thanks for taking the time to read, I appreciate any help you guys can offer.