Tile based lighting system 2d - python-3.x

Question

I am looking for a tile based lighting system for my tile based game. I have not tried anything because I can't think of an effective way to do this. I have searched stack overflow and I found this but its not what I want. I am making a 2d version of Minecraft with pygame.
here is my tile class
class tile():
def __init__(self, block_category, block_type, x, y, world, win):
self.x, self.y, self.width, self.height = (x*64), (y*64), 64, 64
self.block_type = block_type
self.light_level = 1 # i want light level to range from 0-1
self._image = None
self.world = world
self.win = win
self.posx, self.posy = x, y
try:
self._image = self.world.block_textures[block_category][block_type]
except:
self._image = self.world.block_textures["missing"]["missing_texture"]
self.image = self._image
def draw(self):
#draw code here self.posx, self.win, self.world and self.posy are used here if you are wondering
def change_block(self, block_category, block_type):
try:
self._image = self.world.block_textures[block_category][block_type]
except:
self._image = self.world.block_textures["missing"]["missing_texture"]
self.image = self._image
and my world data looks like this
def generate_world(self):
for x in range(0, self.width):
self.tiles[x] = {}
for y in range(0, self.height):
self.tiles[x][y] = tile("terrain", "air", x, y, self, self.win)
for x in range(0, self.width):
for y in range(0, self.height):
if y == 0:
self.tiles[x][y].change_block("terrain", "bedrock")
elif y == 38:
self.tiles[x][y].change_block("terrain", "grass_block")
elif y < 38 and y > 34:
self.tiles[x][y].change_block("terrain", "dirt")
elif y < 35 and y > 0:
self.tiles[x][y].change_block("terrain", "stone")
if x == 0 or x == self.height - 1:
self.tiles[x][y].change_block("terrain", "bedrock")
return self.tiles
my game looks like this

Answer 1

For 2D games like you're making, how we could apply lighting - more like, shadowing - could go into 2 options:
Change screen color to shadow color & set transparency to objects, as OP suggested
Sandwich entire thing between screen and light layer
Let's start with problem of 1st option:
Problem of setting transparency
Here's demo code based on your idea:
"""
Demonstration of color overlapping
"""
import pygame as pg
class Player(pg.sprite.Sprite):
def __init__(self):
super(Player, self).__init__()
self.image = pg.Surface((50, 50))
self.image.fill((255, 255, 255))
self.rect = self.image.get_rect()
# setting alpha on player
self.image.set_alpha(125)
def update(self, *args, **kwargs):
x, y = pg.mouse.get_pos()
c_x, c_y = self.rect.center
self.rect.move_ip(x - c_x, y - c_y)
def mainloop():
player = Player()
screen = pg.display.set_mode((500, 500))
circle_colors = (255, 0, 0), (0, 255, 0), (0, 0, 255)
circle_coords = (150, 250), (250, 250), (350, 250)
# make surface, set alpha then draw circle
bg_surfaces = []
for (color, center) in zip(circle_colors, circle_coords):
surface = pg.Surface((500, 500), pg.SRCALPHA, 32)
surface.convert_alpha()
surface.set_alpha(125)
pg.draw.circle(surface, color, center, 75)
bg_surfaces.append(surface)
running = True
while running:
screen.fill((0, 0, 0))
# draw background
for surface in bg_surfaces:
screen.blit(surface, surface.get_rect())
for event in pg.event.get():
if event.type == pg.QUIT:
running = False
player.update()
screen.blit(player.image, player.rect)
pg.display.flip()
if __name__ == '__main__':
pg.init()
mainloop()
pg.quit()
As you see, now the player (White square)'s color is Mixed with background circles.
It's basically just like what the drawing program does with layers.
Set layer transparency 50% and stack - everything mixes, producing undesirable effect which is far from lighting effect you wanted.
Unless you want Creeper or Steve to blend with the background and become a ghosty figure, it's better to go for sandwiched layout.
Sandwiched Layout
Following is demo code which uses mouse position as light source position.
Rendering order is Ground > Player > light overlay(shadow)
Demo code:
"""
Code demonstration for https://stackoverflow.com/q/72610504/10909029
Written on Python 3.10 (Using Match on input / event dispatching)
"""
import math
import random
import itertools
from typing import Dict, Tuple, Sequence
import pygame as pg
class Position:
"""Namespace for size and positions"""
tile_x = 20
tile_size = tile_x, tile_x
class SpriteGroup:
"""Namespace for sprite groups, with chain iterator keeping the order"""
ground = pg.sprite.Group()
entities = pg.sprite.Group()
light_overlay = pg.sprite.Group()
#classmethod
def all_sprites(cls):
return itertools.chain(cls.ground, cls.entities, cls.light_overlay)
class Player(pg.sprite.Sprite):
"""Player class, which is merely a rect following pointer in this example."""
def __init__(self):
super(Player, self).__init__()
self.image = pg.Surface((50, 50))
self.image.fill((255, 255, 255))
self.rect = self.image.get_rect()
SpriteGroup.entities.add(self)
self.rect.move_ip(225, 225)
def update(self, *args, **kwargs):
pass
# Intentionally disabling mouse following code
# x, y = pg.mouse.get_pos()
# c_x, c_y = self.rect.center
# self.rect.move_ip(x - c_x, y - c_y)
class TileLightOverlay(pg.sprite.Sprite):
"""
Light overlay tile. Using separate sprites, so we don't have to blit on
every object above ground that requires lighting.
"""
# light lowest boundary
lighting_lo = 255
# light effect radius
light_radius = Position.tile_x * 8
def __init__(self, x, y):
super(TileLightOverlay, self).__init__()
self.image = pg.Surface(Position.tile_size)
self.image.fill((0, 0, 0))
self.rect = self.image.get_rect()
self.rect.move_ip(x * Position.tile_x, y * Position.tile_x)
SpriteGroup.light_overlay.add(self)
def update(self, *args, **kwargs):
self.image.set_alpha(self.brightness)
#property
def brightness(self):
"""Calculate distance between mouse & apply light falloff accordingly"""
distance = math.dist(self.rect.center, pg.mouse.get_pos())
if distance > self.light_radius:
return self.lighting_lo
return (distance / self.light_radius) * self.lighting_lo
class TileGround(pg.sprite.Sprite):
"""Ground tile representation. Not much is going on here."""
def __init__(self, x, y, tile_color: Sequence[float]):
super(TileGround, self).__init__()
self.image = pg.Surface(Position.tile_size)
self.image.fill(tile_color)
self.rect = self.image.get_rect()
self.rect.move_ip(x * Position.tile_x, y * Position.tile_x)
SpriteGroup.ground.add(self)
# create and keep its pair light overlay tile.
self.light_tile = TileLightOverlay(x, y)
class World:
"""World storing ground tile data."""
# tile type storing color etc. for this example only have color.
tile_type: Dict[int, Tuple[float, float, float]] = {
0: (56, 135, 93),
1: (36, 135, 38),
2: (135, 128, 56)
}
def __init__(self):
# coord system : +x → / +y ↓
# generating random tile data
self.tile_data = [
[random.randint(0, 2) for _ in range(25)]
for _ in range(25)
]
# generated tiles
self.tiles = []
def generate(self):
"""Generate world tiles"""
for x, row in enumerate(self.tile_data):
tiles_row = [TileGround(x, y, self.tile_type[col]) for y, col in enumerate(row)]
self.tiles.append(tiles_row)
def process_input(event: pg.event.Event):
"""Process input, in case you need it"""
match event.key:
case pg.K_ESCAPE:
pg.event.post(pg.event.Event(pg.QUIT))
case pg.K_UP:
pass
# etc..
def display_fps_closure(screen: pg.Surface, clock: pg.time.Clock):
"""FPS display"""
font_name = pg.font.get_default_font()
font = pg.font.Font(font_name, 10)
color = (0, 255, 0)
def inner():
text = font.render(f"{int(clock.get_fps())} fps", True, color)
screen.blit(text, text.get_rect())
return inner
def mainloop():
# keeping reference of method/functions to reduce access overhead
fetch_events = pg.event.get
display = pg.display
# local variable setup
screen = display.set_mode((500, 500))
player = Player()
world = World()
world.generate()
clock = pg.time.Clock()
display_fps = display_fps_closure(screen, clock)
running = True
# main loop
while running:
screen.fill((0, 0, 0))
# process event
for event in fetch_events():
# event dispatch
match event.type:
case pg.QUIT:
running = False
case pg.KEYDOWN:
process_input(event)
# draw in ground > entities > light overlay order
for sprite in SpriteGroup.all_sprites():
sprite.update()
screen.blit(sprite.image, sprite.rect)
# draw fps - not related to question, was lazy to remove & looks fancy
clock.tick()
display_fps()
display.flip()
if __name__ == '__main__':
pg.init()
pg.font.init()
mainloop()
pg.quit()
You'll see it's blending properly with shadow without mixing color with ground tiles.
There could be much better approach or ways to implement this - as I never used pygame before, there would be bunch of good/better stuffs I didn't read on document.
But one thing for sure - always approach your goal with mindset that everything is related to your problem until you reach the goal! Comment you thought it wasn't going to be helpful gave me idea for this design.

Answer 2

One option is a black background, then I use set_alpha() to set how light or dark the tile is (how much the black background is seen through the tile) and no overlay is needed. Thanks to #jupiterbjy's original answer for inspiration.