Ripples

ripple_demo.py

# Import a library of functions called 'pygame'
import pygame
import numpy as np

# Width and height of display
WIDTH = 255>>0
HEIGHT = 65>>0

# Downscale to ripple grid
SHFT = 2
R_WIDTH = (WIDTH>>SHFT)+1
R_HEIGHT = (HEIGHT>>SHFT)+1

# Initialise front and back buffers
frontbuffer = np.random.randint(255,size=R_WIDTH*R_HEIGHT)
backbuffer = np.random.randint(255,size=R_WIDTH*R_HEIGHT)
print("Using {} bytes of memory".format(R_WIDTH*R_HEIGHT*2))
 
# Initialize the game engine
pygame.init()
screen = pygame.display.set_mode((WIDTH, HEIGHT*2))

done = False
clock = pygame.time.Clock()
while not done:
 
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            done = True
        if event.type == pygame.MOUSEBUTTONDOWN:

            # get mouse position and translate to grid
            x, y = pygame.mouse.get_pos()
            x = min(x>>SHFT, R_WIDTH-1)
            y = min(y>>SHFT, R_HEIGHT-1)
            frontbuffer[x + R_WIDTH*y] = 255 # create ripple

    # Draw screen based on backbuffer
    for x in range(0, WIDTH):
        for y in range(0, HEIGHT):
            x_ = min(x>>SHFT, R_WIDTH-1)
            y_ = min(y>>SHFT, R_HEIGHT-1)
            color = backbuffer[x_ + R_WIDTH*y_]
            try:
                pygame.draw.rect(screen, (color,color,color), [x, y, 1, 1], 2)
            except:
                print(color)

    for x in range(0, WIDTH):
        for y in range(HEIGHT, HEIGHT*2):
            x_ = min(x>>SHFT, R_WIDTH-1)
            y_ = min((y-HEIGHT)>>SHFT, R_HEIGHT-1)
            color = frontbuffer[x_ + R_WIDTH*y_]
            try:
                pygame.draw.rect(screen, (color,color,color), [x, y, 1, 1], 2)
            except:
                print(color)

    # Calculate wave propogation as in
    # https://web.archive.org/web/20160418004149/http://freespace.virgin.net/hugo.elias/graphics/x_water.htm
    for x in range(0, R_WIDTH):
        for y in range(0, R_HEIGHT):
            x_n = x-1 if x != 0 else x+1
            x_p = x+1 if x != R_WIDTH-1 else x-1
            y_n = y-1 if y != 0 else y+1
            y_p = y+1 if y != R_HEIGHT-1 else y-1
            backbuffer[x + R_WIDTH*y] = min(max((frontbuffer[x_p + R_WIDTH*y] +
                                               frontbuffer[x_n + R_WIDTH*y] +
                                               frontbuffer[x + R_WIDTH*y_p] +
                                               frontbuffer[x + R_WIDTH*y_n] ) // 2 - \
                                               backbuffer[x + R_WIDTH*y], 0), 255)

            backbuffer[x + R_WIDTH*y] -= int(backbuffer[x + R_WIDTH*y])>>5
 

    # swap buffers
    temp = frontbuffer
    frontbuffer = backbuffer
    backbuffer = temp

    pygame.display.flip()
 
# Be IDLE friendly
pygame.quit()