# J-Filters VI

Using a vector and an angle, rotating each pixel’s position by an angle determined by its distance to the image’s center and a constant, this filter gives the image a unique spin.
For demonstration I used – once again – an image from my post Stacking Stones.

``````# Python 2.7.7 Code
# Pygame 1.9.1 (for Python 2.7.7)
# Jonathan Frech 19th of February, 2016``````

``````# importing needed modules
import pygame, sys, time, math, os

# this constant changes the spin
CONSTANT = .9

""" FUNCTIONS """
# gets the position on a circle with a position, radius and an angle
def getCirclePos(_pos, _radius, _angle):
return [
]

# returns an integer version of given positon
def intpos(_pos):
return [int(_pos[0]), int(_pos[1])]

# basic vector functions
def vecConvert(p1, p2):
return [p2[0] - p1[0], p2[1] - p1[1]]
def vecLen(vec):
return math.sqrt( (vec[0]**2) + (vec[1]**2) )

""" GAME """
# game class
class GAME():
# initialize program
def __init__(self):
self.image = pygame.image.load(os.getcwd() + "/original.jpg")
self.rect = self.image.get_rect()
self.image = pygame.transform.scale(self.image, [self.rect.right / 2, self.rect.bottom / 2])
self.rect = self.image.get_rect()

self.shiftx, self.shifty = 300, 300

self.width, self.height = self.rect.right + self.shiftx*2, self.rect.bottom + self.shifty*2
self.size = [self.width, self.height]
self.surface = pygame.Surface(self.size)
self.screen = pygame.display.set_mode(self.size)

self.ticks = 0
self.running = True

self.i = 0

# functions
pygame.display.set_caption("J-Filters VI")

# tick function
def tick(self):
# handle events
for event in pygame.event.get():
if event.type == pygame.QUIT:
self.quit()
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_SPACE:
self.screenshot()

# loop through
for _ in range(0, self.width):
# get positions
x, y = self.i % self.rect.right, self.i / self.rect.right
p = [self.rect.right / 2., self.rect.bottom / 2.]

# calculate pixel's angle
angle = math.atan2(y - p[1], x - p[0])
angle = math.degrees(angle)

# calculate pixel's distance to the center
vec = vecConvert(p, [x, y])
vecl = vecLen(vec)

# calculate angle change
angleadd = vecl * CONSTANT

# calculate new position
P = intpos(getCirclePos(p, vecl, angle+angleadd))
P = [P[0]+self.shiftx, P[1]+self.shifty]

# draw
pygame.draw.circle(self.surface, self.image.get_at([x, y]), P, 2)

# advance running variable i
if self.i < (self.rect.right * self.rect.bottom)-1:
self.i += 1

# render function
def render(self):

# blit and flip
self.screen.blit(self.surface, [0, 0])
pygame.display.flip()

# quits
def quit(self):
self.running = False

# takes a screenshot
def screenshot(self):
path = os.getcwd() + "/out/"

try:
if not os.path.isdir(path):
os.mkdir(path)

name = "img" + str(len(os.listdir(path))) + ".png"
pygame.image.save(self.surface, path + name)
except:
pass

# run function (uses tick() and render())
def run(self):
ticksPerSecond = 60
lastTime = time.time() * 1000000000
nsPerTick =  1000000000.0 / float(ticksPerSecond)

ticks = 0
frames = 0

lastTimer = time.time() * 1000
delta = 0.0

while self.running:
now = time.time() * 1000000000
delta += float(now - lastTime) / float(nsPerTick)
lastTime = now
shouldRender = False

while delta >= 1:
ticks += 1
self.ticks += 1
self.tick()
delta -= 1
shouldRender = True

if shouldRender:
frames += 1
self.render()

if time.time() * 1000 - lastTimer >= 1000:
lastTimer += 1000

# debug
#print("Frames: " + str(frames) + ", ticks: " + str(ticks))

frames = 0
ticks = 0

# start game
G = GAME()
G.run()``````