generativeart/waves.py

#!/usr/bin/env python3

import cairo
import math
from utils import random_color


# dimensions of the output image
WIDTH, HEIGHT = 1024, 1024
# numbers of waves
WAVES = 10
# how much should the phases be offset?
WAVE_OFFSET = -0.7
# amplitude of the sine wave
AMPLITUDE = 25
# only 1 color with shades?
MONOCHROME = True
# background black? White otherwise:
DARK_BG = True
# precision of the calculation
PRECISION = 10000

def main():
    
    surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, WIDTH, HEIGHT)
    ctx = cairo.Context(surface)

    ctx.scale(WIDTH, HEIGHT)  # Normalizing the canvas

    wave_height = 1/WAVES
    step_size = 1/PRECISION

    lastpoints = [(x/PRECISION, 0) for x in range(PRECISION+1)]
    if DARK_BG:
        # make bg black
        ctx.rectangle(0, 0, 1, 1)
        ctx.set_source_rgb(0, 0, 0)
        ctx.fill()
    
    if MONOCHROME:
        r, g, b = random_color()
        alpha_step = 1/WAVES

    for num in range(WAVES+1):
        if not MONOCHROME:
            r, g, b = random_color()
        points = []
        x = 0
        while x < 1:
            y = math.sin(x*AMPLITUDE + (num * WAVE_OFFSET) ) * 0.1 
            points.append((x, ( (y/4) + ((0.5+num)*wave_height))))
            x += step_size
        print(f'Draw {len(points)} points for curve {num}')
        if not MONOCHROME:
            ctx.set_source_rgb(r, g, b)
        else:
            ctx.set_source_rgba(r, g, b, 1 - (alpha_step * num)) # make more transparent toward bottom
        # draw waves
        ctx.move_to(*points[0])
        for p in points[1:]:
            ctx.line_to(*p)
        for p in reversed(lastpoints):
            ctx.line_to(*p)
        ctx.line_to(*points[0])
        ctx.fill()
        lastpoints = points


    surface.write_to_png("out/waves.png")  # Output to PNG

if __name__ == '__main__':
    main()