Add rotating triangles around an icon

rotateicon.py

from PIL import Image, ImageDraw
import math, os

def DrawTri(im, draw, ang):
	vec = [math.cos(ang), -math.sin(ang)]
	cross = [vec[1], -vec[0]]

	cent = [im.size[0]/2.0, im.size[1]/2.0]
	ln = min(cent)
	pos = (cent[0]+vec[0]*ln, cent[1]+vec[1]*ln)
	tri = (cent[0]+vec[0]*ln*0.8, cent[1]+vec[1]*ln*0.8, pos[0]+ln*0.2*cross[0], pos[1]+ln*0.2*cross[1], pos[0]-ln*0.2*cross[0], pos[1]-ln*0.2*cross[1])

	draw = ImageDraw.Draw(im)
	draw.polygon(tri, fill=(255,255,255,192))
	del draw

if __name__=="__main__":

	for fina in ["arrows.png", "broken-amphora.png", "luxury.png", "pot-of-gold.png", "pyramid-of-the-sun.png", "question.png"]:
		finaSp = os.path.splitext(fina)
		print finaSp

		for i in range(10):
			im = Image.open(fina)
			im = im.convert("RGBA")

			ang = i * math.pi / 20.0

			draw = ImageDraw.Draw(im)
			DrawTri(im, draw, ang)
			DrawTri(im, draw, ang + math.pi/2.0)
			DrawTri(im, draw, ang + math.pi)
			DrawTri(im, draw, ang + math.pi*1.5)
			del draw

			im.save("{}{}{}".format(finaSp[0], i, finaSp[1]))