randomart.py

import random
import math
import PIL.Image

funcs = [
    ('add', 2, 1),
    ('mult', 2, 1),
    #('atan2', 2, 1),
    #('floor', 1, 1),
    #('ceil', 1, 1),
    #('sin', 1, 1),
    #('logistics', 1, 1),
    #('sqrt_squared', 1, 1),
    ('if_then_else', 3, 1),
    ('dist', 2, 1),
    ('copysign', 2, 1),
]

funcs.append(('terminator', 0, sum(f[2] for f in funcs) / 4))

evaluators = {
    'add': lambda x, y: x + y,
    'mult': lambda x, y: x * y,
    'sin': lambda x: math.sin(x),
    'sqrt_squared': lambda x: math.sqrt(x**2),
    'if_then_else': lambda x, y, z: y if x > 0 else z,
    'logistics': lambda x: 1 / (1 + math.exp(-1)),
    'dist': lambda x, y: math.sqrt(x**2 + y**2),
    'atan2': lambda x, y: math.atan2(y, x),
    'floor': math.floor,
    'ceil': math.ceil,
    'copysign': math.copysign,
}

def generate(depth):
    while depth > 0 and random.random() < 0.5:
        depth -= 1
    func = random.choices(funcs, weights=[f[2] for f in funcs])[0]
    if depth <= 0:
        func = funcs[-1]
    if func[0] == 'terminator':
        return random.choice(['x', 'y', random.uniform(-1, 1)])
    ret = [func[0]]
    for i in range(func[1]):
        ret.append(generate(depth-1))
    return ret

def evaluate(expr, x, y):
    if isinstance(expr, list):
        args = []
        for a in expr[1:]:
            args.append(evaluate(a, x, y))
        return evaluators[expr[0]](*args)
    elif expr == 'x':
        return x
    elif expr == 'y':
        return y
    else:
        return expr

DEPTH = 15
MODE = 'HSV' # RGB
WIDTH = 400
HEIGHT = 400

def main():
    r_expr = generate(DEPTH)
    g_expr = generate(DEPTH)
    b_expr = generate(DEPTH)
    print(f'{r_expr = }')
    print(f'{g_expr = }')
    print(f'{b_expr = }')
    img = bytearray()
    for y_px in range(HEIGHT):
        y = (y_px / HEIGHT) * 2 - 1
        for x_px in range(WIDTH):
            x = (x_px / WIDTH) * 2 - 1
            r = int(((evaluate(r_expr, x, y) + 1) / 2) * 255) % 256
            g = int(((evaluate(g_expr, x, y) + 1) / 2) * 255) % 256
            b = int(((evaluate(b_expr, x, y) + 1) / 2) * 255) % 256
            img.append(r)
            img.append(g)
            img.append(b)
    out = PIL.Image.frombytes(MODE, (WIDTH, HEIGHT), img)
    out.convert('RGB').save('output.png')

if __name__ == '__main__':
    main()