Got it working.

2d_sponge.py

@@ -0,0 +1,182 @@
+#!/usr/bin/python3
+
+import pygame
+import threading
+
+RESOLUTION = 8
+FPS = 60
+
+
+pygame.init()
+
+screen = pygame.display.set_mode((1600, 900), flags=pygame.RESIZABLE)
+
+
+white = (240, 240, 240)
+red = (200, 40, 40)
+gray = (40, 40, 40)
+
+sponge = None
+sponge_step = 0
+sponge_last_step = (RESOLUTION - 1) * 3 * 3
+
+
+clock = pygame.time.Clock()
+sponge_surface = pygame.Surface((3**RESOLUTION, 3**RESOLUTION))
+sponge_surface.fill(gray)
+font = pygame.font.Font(pygame.font.get_default_font(), 32)
+
+
+class SimpleArray:
+    def __init__(self, size: tuple, fill=None):
+        self.size = size
+        self.width, self.height = size
+
+        self.fill = fill
+
+        self.array = []
+        self.empty_array = []
+
+        self.create_array()
+
+    def __str__(self):
+        array_string = ""
+
+        for y in self.array:
+            for x in y:
+                array_string += str(x)
+
+            array_string += "\n"
+
+        return array_string
+
+    def create_array(self):
+        for y in range(self.height):
+            array = []
+            for x in range(self.width):
+                array.append(self.fill)
+
+            self.array.append(array)
+
+        self.empty_array = self.array
+
+    def set(self, pos: tuple, value):
+        x, y = pos
+
+        self.array[y - 1][x - 1] = value
+
+    def set_all(self, array: list):
+        self.array = array
+
+    def merge(self, pos: tuple, array):
+        width, height = array.size
+
+        offset_x, offset_y = pos
+
+        for y in range(height):
+            for x in range(width):
+                self.set((x + offset_x + 1, y + offset_y + 1), array.get((x + 1, y + 1)))
+
+    def get(self, pos: tuple):
+        x, y = pos
+
+        return self.array[y - 1][x - 1]
+
+    def get_all(self):
+        return self.array
+
+    def reset(self):
+        self.array = self.empty_array
+
+
+def generate_sponge():
+    global sponge
+    global sponge_step
+
+    pattern = SimpleArray((1, 1), fill=1)
+
+    for pattern_number in range(2, RESOLUTION + 1):
+        if not running:
+            return
+
+        old_size = pattern.height
+        new_size = old_size * 3
+
+        new_pattern = SimpleArray((new_size, new_size), fill=0)
+
+        for y in range(1, 4):
+            for x in range(1, 4):
+                if not x == 2 or not y == 2:
+                    new_pattern.merge((x * old_size - old_size, y * old_size - old_size), pattern)
+
+                sponge_step += 1
+
+        pattern = new_pattern
+
+    sponge = pattern
+
+    draw_sponge()
+
+
+def draw_sponge():
+    global sponge_step
+
+    sponge_surface.fill(gray)
+
+    for y in range(3**(RESOLUTION - 1)):
+        for x in range(3**(RESOLUTION - 1)):
+            if sponge.get((x + 1, y + 1)) == 1:
+                sponge_surface.set_at((x, y), white)
+
+
+def update():
+    screen.fill(gray)
+
+    screen.blit(sponge_surface, (0, 0))
+
+    calculate_progress()
+
+    check_events()
+
+    if not running:
+        return
+
+    pygame.display.update()
+
+
+def calculate_progress():
+    if not sponge_step == sponge_last_step:
+        percent = 100 / sponge_last_step
+        step_percent = round(percent * sponge_step)
+
+        loading_text = font.render("Loading: " + str(step_percent) + "%", True, red)
+
+        x, y = screen.get_size()
+        tx, ty = loading_text.get_size()
+
+        screen.blit(loading_text, (x / 2 - tx / 2, y / 2 - ty / 2))
+
+
+def check_events():
+    for event in pygame.event.get():
+        if event.type == pygame.QUIT:
+            close()
+
+
+def close():
+    global running
+
+    running = False
+
+
+running = True
+
+threading.Thread(target=generate_sponge).start()
+
+while running:
+    update()
+
+    clock.tick(FPS)
+
+pygame.quit()
+print("Exit.")