Python Pygame - Lighting Efftect

import pygame
from pygame import Rect
from pygame import Vector2
import lzma, base64
from random import randint
import time

class tile:
    def __init__(s, xy):
        global TILE_SIZE
        s.v = Vector2(xy) * TILE_SIZE
        s.r = Rect(s.v, (TILE_SIZE, TILE_SIZE))
        s.oc = (randint(0, 128), randint(0, 128), randint(0, 128))

    def draw(s):
        global PDS
        pygame.draw.rect(PDS, s.oc, s.r)

class timer:
    def __init__(s, seconds):
        s.ts = time.time()
        s.seconds = seconds

    def update(s):
        now = time.time()
        duration = now - s.ts
        frames = int(duration / s.seconds)
        if frames >= 1:
            s.ts = now
        return frames

def lerp(start, end, t):
    return start + t * (end - start)

def chunks(l, n):
    n = max(1, n)
    return [l[i:i+n] for i in range(0, len(l), n)]

def unzip_map(b64lztm, ms):
    tilemapData = lzma.decompress(base64.b64decode(b64lztm))
    tileData = chunks(list(bytes(tilemapData)), ms[0])
    return tileData

pygame.init()
PDR = Rect(0, 0, 1280, 720)
PDS = pygame.display.set_mode(PDR.size)

LIGHT_COLOR = (255, 255, 255)
LIGHT_RADIUS = 100
LIGHT_SIZE = (LIGHT_RADIUS * 2, LIGHT_RADIUS * 2)
LIGHT_STEP = 1 / LIGHT_RADIUS
CHANGE_LIGHT = timer(2)

B64LZ_MAP = b'/Td6WFoAAATm1rRGAgAhARYAAAB0L+Wj4I//A+FdAADv+///o7f/QH7h8+istaVmxFJbf3DyyvZOfLJYj4Vfhg0C/LVwslsyx\
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fewS/6KYw++8RgFH+GIl9U+xKxdWi1VIaxEQlFLRsQuadanXG0h+QVWHw+LG/Zwp1ekgDEWeQpIZ5w5Gox/R2DQe/vU1BlmsNVggTT8SyUnYQg1\
/S/ks3WGRBQDmB9VdW397v06wl9K62YCfkcULFRotgPasltMf/pC3MltOOc6yGZl9TtcmMsYIX3VsqKyZMZneLFtDwLRHsAPQEzDjeWlpKbgwG2\
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MAP_SIZE = (256, 144)
TILE_SIZE = 5
MAP = unzip_map(B64LZ_MAP, MAP_SIZE)
for row in range(MAP_SIZE[1]):
    for col in range(MAP_SIZE[0]):
        if not MAP[row][col]: continue
        MAP[row][col] = tile((col, row))
        MAP[row][col].draw()

# define some colors
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
RED = (128, 0, 0)

quitDemo = False
while not quitDemo:
    events = pygame.event.get()
    for event in events:
        if event.type == pygame.QUIT:
            quitDemo = True
    if CHANGE_LIGHT.update():
        LIGHT_COLOR = (randint(128, 255), randint(128, 255), randint(128, 255))


    mp = Vector2(pygame.mouse.get_pos())
    mr = Rect(mp - (LIGHT_RADIUS, LIGHT_RADIUS), LIGHT_SIZE)
    aligned_mp = mp // TILE_SIZE * TILE_SIZE
    aligned_mr = Rect(aligned_mp - (LIGHT_RADIUS, LIGHT_RADIUS), LIGHT_SIZE)
    for x in range(aligned_mr.left, aligned_mr.right, TILE_SIZE):
        for y in range(aligned_mr.top, aligned_mr.bottom, TILE_SIZE):
            if x < 0 or x >= PDR.w or y < 0 or y >= PDR.h: continue
            d = abs(Vector2(x, y).distance_to(mp))
            if d <= LIGHT_RADIUS:
                t = MAP[y // TILE_SIZE][x // TILE_SIZE]
                if not t:
                    r = int(lerp(LIGHT_COLOR[0] - 128, 0, LIGHT_STEP * d))
                    g = int(lerp(LIGHT_COLOR[1] - 128, 0, LIGHT_STEP * d))
                    b = int(lerp(LIGHT_COLOR[2] - 128, 0, LIGHT_STEP * d))
                else:
                    r = int(lerp(LIGHT_COLOR[0], t.oc[0], LIGHT_STEP * d))
                    g = int(lerp(LIGHT_COLOR[1], t.oc[1], LIGHT_STEP * d))
                    b = int(lerp(LIGHT_COLOR[2], t.oc[2], LIGHT_STEP * d))
                pygame.draw.rect(PDS, (r, g, b), (x, y, TILE_SIZE, TILE_SIZE))

    pygame.display.update()
    pygame.time.Clock().tick(120)