Animation #3 - Make snowing gif animation using OpenCV, PIL

The method of making gif animation is omitted because it was explained earlier. In this post, we use the random module to create a random number of snow particles and then shake them to the ground over time. Unlike the previous post, there is no image to prepare in advance.

Create snowing animation



import cv2
import numpy as np
from PIL import Image
from PIL import ImageDraw
import time, os
import argparse
from random import *

parser = argparse.ArgumentParser(description="OpenCV Example")
parser.add_argument("--maxcnt", default = 5, type=int, help="X axis snow max count")
parser.add_argument("--mincnt", default = 1, type=int, help="X axis snow min count")
parser.add_argument("--size", default = 5, type=int, help="snowball size(diameter)")
args = parser.parse_args()


count = 0
FPS = 5
SLEEP = 2.0 / FPS

height = 480
width = 640
canvas = np.zeros((height,width,3), np.uint8)
img = None
gif_frames = []
snow_balls = []

v_snow_cnt = int(height / (FPS * 4) )
v_step = int(height / v_snow_cnt)
h_snow_cnt = args.maxcnt
snow_balls = []
snow_color = (255, 255, 255) 

def save_gif(frames, gifname, speed):   #speed 100
    frames[0].save(gifname, format='GIF', append_images=frames[1:], save_all=True, duration=speed, loop=0)


def create_snowball():
    global snow_balls
    seed(time.time())
    snows = []
    count = randint(args.mincnt, args.maxcnt)
    for i in range(count):
        snow = randint(1, width)
        snows.append(snow)
    snow_balls.insert(0, snows)

    '''
    remove old snow
    '''
    if(len(snow_balls) > v_snow_cnt): 
        snow_balls.pop(v_snow_cnt)

'''
move the horizontal position
'''

def fall_down():
    global snow_balls
    Tsnow_balls = []
    for snows in snow_balls:
        Tsnows = []
        seed(time.time())
        for snow in snows:
            move = randint(-5, 5)
            snow += move
            Tsnows.append(snow)
        Tsnow_balls.append(Tsnows)    
    snow_balls = Tsnow_balls.copy()

def draw_image():
    global img
    img = canvas.copy()
    line = 0
    for snows in snow_balls:
        for snow in snows:
            img = cv2.circle(img, (snow, line * v_step), args.size, snow_color, -1)
        line += 1
    cv2.imshow('snow', img)
    cv2.waitKey(1)


count = 0
Save = False
while True:
    try:
        start = time.time()
        create_snowball()
        fall_down()
        draw_image()
        end = time.time()
        time.sleep(max(0, SLEEP - (end - start)))
        count += 1
        if count <= v_snow_cnt:
            im_pil = Image.fromarray(img)
            gif_frames.append(im_pil)
        else:
            if Save == False:
                Save = True
                save_gif(gif_frames, "./snawball.gif", 100)


    except KeyboardInterrupt:
        break    

cv2.destroyAllWindows()
<animation-snowball.py>

If you run the code above, you can see that the eye_test.gif file is created as follows.



By adjusting the maxcnt, mincnt, and size values, as well as the fall_down function's (-5,5) value, you can control the amount of snow particles and the animation result.

More smooth snowing animation

In the above example, the X position of the snow particles was randomly adjusted according to the time interval. This time, let's smoothly follow the sin curve.


import cv2
import numpy as np
from PIL import Image
from PIL import ImageDraw
import time, os
import argparse
import math
from random import *

parser = argparse.ArgumentParser(description="OpenCV Example")
parser.add_argument("--maxcnt", default = 5, type=int, help="X axis snow max count")
parser.add_argument("--mincnt", default = 1, type=int, help="X axis snow min count")
parser.add_argument("--size", default = 5, type=int, help="snowball size(diameter)")
args = parser.parse_args()


count = 0
FPS = 20
SLEEP = 2.0 / FPS

height = 480
width = 640
canvas = np.zeros((height,width,3), np.uint8)
img = None
gif_frames = []
snow_balls = []

v_snow_cnt = int(height / 2 )
v_step = int(height / v_snow_cnt)
h_snow_cnt = args.maxcnt
snow_balls = []
snow_balls_shift = []
snow_color = (255, 255, 255) 

def save_gif(frames, gifname, speed):   #speed 100
    frames[0].save(gifname, format='GIF', append_images=frames[1:], save_all=True, duration=speed, loop=0)


def create_snowball():
    global snow_balls, snow_balls_shift
    seed(time.time())
    snows = []
    shifts = []
    if count % 20 == 0:
        snow_count = randint(1, 3)
        for i in range(snow_count):
            shift = random() * 2 * math.pi #radian
            snow = randint(1, width)
            snows.append(snow)
            shifts.append(shift)
    elif count % 20 == 10:
        snow_count = randint(args.mincnt, args.maxcnt)
        for i in range(snow_count):
            shift = random() * 2 * math.pi #radian
            snow = randint(1, width)
            snows.append(snow)
            shifts.append(shift)
    snow_balls.insert(0, snows)
    snow_balls_shift.insert(0, shifts)

    '''
    remove old snow
    '''
    if(len(snow_balls) > v_snow_cnt): 
        snow_balls.pop(v_snow_cnt)
        snow_balls_shift.pop(v_snow_cnt)

'''
move the horizontal position
'''
A = 2
B = 8 * math.pi / v_snow_cnt
def fall_down_sin():
    global snow_balls
    Tsnow_balls = []
    lcnt = 0
    for snows in snow_balls:
        Tsnows = []
        seed(time.time())
        scnt = 0
        for snow in snows:
            angle = (B * lcnt) + snow_balls_shift[lcnt][scnt]
            move = A*math.sin(angle)
            snow += move
            Tsnows.append(snow)
            scnt += 1
        Tsnow_balls.append(Tsnows)
        lcnt += 1    
    snow_balls = Tsnow_balls.copy()

def draw_image():
    global img
    img = canvas.copy()
    line = 0
    for snows in snow_balls:
        for snow in snows:
            img = cv2.circle(img, (int(snow), line * v_step), args.size, snow_color, -1)
        line += 1
    cv2.imshow('snow', img)
    cv2.waitKey(1)


count = 0
Save = False
while True:
    try:
        start = time.time()
        create_snowball()
        fall_down_sin()
        draw_image()
        end = time.time()
        time.sleep(max(0, SLEEP - (end - start)))
        count += 1
        if count <= v_snow_cnt:
            im_pil = Image.fromarray(img)
            gif_frames.append(im_pil)
        else:
            if Save == False:
                Save = True
                save_gif(gif_frames, "./snawball.gif", 200)


    except KeyboardInterrupt:
        break    

cv2.destroyAllWindows()
<animation-snowball2.py>
If you run the code above, you can see that the eye_test.gif file is created as follows.


python animation-snowball2.py --size=8




By adjusting the maxcnt, mincnt, and size values, as well as the fall_down_sin function's A, B value, you can control the amount of snow particles and the particle's sin path.

You can download the source codes here(https://github.com/raspberry-pi-maker/OpenCV)









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