sketch_2022_05_20 (see next toot for the most recent version)
Naive sand simulator… #Processing #Python #numpy #py5

import numpy as np
import py5

def setup():

global grid
py5.size(500, 500)
grid = np.zeros((py5.width, py5.height), dtype=bool)

def draw():

py5.set_np_pixels(grid * 128, 'L')
update_grid()

def update_grid():

for i in reversed(range(grid.shape[0]-1)):
    row, next_row = grid[i], grid[i+1]
        sand = row == 1
    next_row_empty = next_row == 0
    falling = sand & next_row_empty
    row[falling] = 0
    next_row[falling] = 1
    sand_right = row[1:] == 1
    next_left_empty = next_row[:-1] == 0
    falling_left = sand_right & next_left_empty
    row[1:][falling_left] = 0        
    next_row[:-1][falling_left] = 1
    sand_left = row[:-1] == 1
    next_right_empty = next_row[1:] == 0
    falling_right = sand_left & next_right_empty
    row[:-1][falling_right] = 0        
    next_row[1:][falling_right] = 1

def key_pressed():

if py5.key == ' ':
    grid[:] = np.zeros((py5.width, py5.height), dtype=bool)

def mouse_dragged():

x = py5.mouse_x % py5.width
y = py5.mouse_y % py5.height
if py5.is_key_pressed:
    grid[y-4:y+5,x-4:x+5] = 1
else:
    grid[y,x] = 1

py5.run_sketch()