[Python] How can I prevent bouncing entities from phasing through walls in pygame? [duplicate]

I've been having a lot of issues working out collision for my pygame project. I'm making a little simulation/game where horses bounce around an arena in random directions from their collisions, where the arena and horses use pixel masks for their collision. Currently, if a horse collides with the arena or another horse, the horse will reflect back in the opposite direction with 40 degrees of variance.

MirroredAngle = (180 - self.direction)
self.direction = MirroredAngle + random.randint(-20,20)


Unfortunately, the horses are prone to randomly clipping and phasing through walls, despite all the measures I've taken to prevent this.

Full code:

#settingup

import pygame
import math
import random
import os
from time import sleep
clock = pygame.time.Clock()
pygame.init()
screen = pygame.display.set_mode((629,400))
pygame.display.set_caption("Horse Race")

countdown = False
paused = False

#assetgallery
background = pygame.image.load("assets/backgrounds/paddock.png")
background = pygame.transform.scale(background,(629,400))
arena1img = pygame.image.load("assets/arenas/arena1.png")
arena1img = pygame.transform.scale(arena1img,(629,400))
arena2img = pygame.image.load("assets/arenas/arena2.png")
arena2img = pygame.transform.scale(arena2img,(629,400))
arena3img = pygame.image.load("assets/arenas/arena3.png")
arena3img = pygame.transform.scale(arena3img,(629,400))
arena1mask = pygame.mask.from_surface(arena1img.convert_alpha(),1)
arena2mask = pygame.mask.from_surface(arena2img.convert_alpha(),1)
gate = pygame.image.load("assets/general/GATE.png")

class Arena(pygame.sprite.Sprite):
def __init__(self,arena,name):
pygame.sprite.Sprite.__init__(self)
self.image = arena
self.name = name
self.mask = pygame.mask.from_surface(self.image.convert_alpha())
self.rect = arena.get_rect()
self.rect.topleft = (0,0)


allgroup = pygame.sprite.Group()

alllist = []

'''
def iterateangles(tsthorse):
foundgoodangle = False
angletoreturn = None
while True:
if foundgoodangle == True:
break
else:
randangle = random.randint(0,360)
theoreticalstepx = tsthorse.x + (4*math.sin(math.radians(tsthorse.direction)))
theoreticalstepy = tsthorse.y + (4*math.cos(math.radians(tsthorse.direction)))
theoreticalrect = tsthorse.image.get_rect()
theoreticalrect.topleft = (theoreticalstepx,theoreticalstepy)
theoreticalmask = pygame.mask.from_surface(tsthorse.image)
screen.blit(theoreticalmask.to_surface(None,None,None,(255,255,255,255),(0,0,0,255)),(theoreticalrect.x,theoreticalrect.y))
for x in alllist:
offsrt = (theoreticalrect.x - x.rect.x), (theoreticalrect.y - x.rect.y)
if x.mask.overlap(theoreticalmask,offsrt):
pass
else:
foundgoodangle = True
angletoreturn = randangle

return angletoreturn
'''



#horses
class Horse(pygame.sprite.Sprite):
def __init__(self,color,x,y,direction,name):
pygame.sprite.Sprite.__init__(self)
self.x = x
self.y = y
self.direction = direction
self.color = color
self.name = name
self.archivex = self.x
self.archivey = self.y
if self.direction > 44 and self.direction < 135:
self.image = pygame.image.load(f"assets/horses/{self.color}/down.png")
self.cardinal = "down"
elif self.direction > 134 and self.direction < 220:
self.image = pygame.image.load(f"assets/horses/{self.color}/left.png")
self.cardinal = "left"
elif self.direction > 219 and self.direction < 310:
self.image = pygame.image.load(f"assets/horses/{self.color}/up.png")
self.cardinal = "up"
elif self.direction > 310 or self.direction < 45:
self.image = pygame.image.load(f"assets/horses/{self.color}/right.png")
self.cardinal = "right"


self.image = pygame.transform.scale(self.image.convert_alpha(),(25,25))
self.mask = pygame.mask.from_surface(self.image)
self.rect = self.image.get_rect()
self.rect.topleft = (self.x,self.y)

def update(self):
if self.direction > 44 and self.direction < 135:
self.image = pygame.image.load(f"assets/horses/{self.color}/down.png")
self.cardinal = "down"
elif self.direction > 134 and self.direction < 220:
self.image = pygame.image.load(f"assets/horses/{self.color}/left.png")
self.cardinal = "left"
elif self.direction > 219 and self.direction < 310:
self.image = pygame.image.load(f"assets/horses/{self.color}/up.png")
self.cardinal = "up"
elif self.direction > 310 or self.direction < 45:
self.image = pygame.image.load(f"assets/horses/{self.color}/right.png")
self.cardinal = "right"
self.image = pygame.transform.scale(self.image.convert_alpha(),(25,25))
self.mask = pygame.mask.from_surface(self.image)
self.rect = self.image.get_rect()
self.rect.topleft = (self.x,self.y)
#collisions
for x in alllist:
if x != self:
offsrt = (self.rect.x - x.rect.x), (self.rect.y - x.rect.y)
if x.mask.overlap(self.mask,offsrt):
if isinstance(x,Horse):
print(self.name + " has ran into " + x.name)
x.x = x.archivex
x.y = x.archivey


self.x = self.archivex
self.y = self.archivey
#self.direction = iterateangles(self)
# print("collision between " + self.name +" and " + x.name)
MirroredAngle = (180 - self.direction)
self.direction = MirroredAngle + random.randint(-20,20)
'''
if self.cardinal == "right":
self.direction += (90)
elif self.cardinal == "down":
self.direction -= (180)
elif self.cardinal == "left":
self.direction -= (90)
else:
self.direction += (180)
'''
if self.direction > 360:
self.direction -= 360
elif self.direction < 0:
self.direction = 360 + self.direction
#print(self.direction)
else:
self.archivex = self.x
self.archivey = self.y





#arenas
arena2 = Arena(arena3img,"arena 3")


activearena = arena2



#horses
orange = Horse("orange",20,30,90,"Wonderful Introspective Morning")
green = Horse("green",60,30,170,"Pay Dock")
brown = Horse("brown",100,30,60,"Data Same Day")
pink = Horse("pink",20,70,90,"Troy Matthews")
cyan = Horse("cyan",60,70,100,"Cynical Chew Toy")

alllist.append(orange)
#alllist.append(green)
#alllist.append(brown)
#alllist.append(pink)
#alllist.append(cyan)
alllist.append(arena2)

horsegroup = pygame.sprite.Group()

horsegroup.add(orange)
horsegroup.add(green)
horsegroup.add(brown)
horsegroup.add(pink)
horsegroup.add(cyan)


def movehorses():
for obj in horsegroup:
# print("hi im going " + str(obj.direction))

obj.x += (2*math.sin(math.radians(obj.direction)))
obj.y += (2*math.cos(math.radians(obj.direction)))
obj.update()


def showhorses():
for obj in horsegroup:
screen.blit(obj.image,(obj.x,obj.y))
#screen.blit(obj.mask.to_surface(None,None,None,(255,255,255,255),(0,0,0,255)),(obj.x,obj.y))



while True:
if countdown == False and paused == False:
movehorses()
screen.blit(background,(0,0))
screen.blit(arena3img,(0,0))
#screen.blit(arena2.mask.to_surface(None,None,None,(255,255,255,255),(0,0,0,255)),(0,0))
showhorses()
for event in pygame.event.get():
if event.type == pygame.QUIT:
pygame.quit()
pygame.display.flip()
clock.tick(60)





I've tried making it so that the horses are set back to their last position whenever they are in a collision, but that only helped slightly and did not fully phase out the clipping. I've tried reducing the horse count to only one horse, which stopped the clipping, but when I tried to reintroduce the other horses without them being able to collide with each other, they still phased through the walls.

Here is a video of this in effect: Video

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