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#! /usr/bin/env python
print "OpenCV Python version of convexhull"
# import the necessary things for OpenCV
from opencv import cv
from opencv import highgui
# to generate random values
import random
# how many points we want at max
_MAX_POINTS = 100
if __name__ == '__main__':
# main object to get random values from
my_random = random.Random ()
# create the image where we want to display results
image = cv.cvCreateImage (cv.cvSize (500, 500), 8, 3)
# create the window to put the image in
highgui.cvNamedWindow ('hull', highgui.CV_WINDOW_AUTOSIZE)
while True:
# do forever
# get a random number of points
count = my_random.randrange (0, _MAX_POINTS) + 1
# initialisations
points = []
for i in range (count):
# generate a random point
points.append (cv.cvPoint (
my_random.randrange (0, image.width / 2) + image.width / 4,
my_random.randrange (0, image.width / 2) + image.width / 4
))
# compute the convex hull
hull = cv.cvConvexHull2 (points, cv.CV_CLOCKWISE, 0)
# start with an empty image
cv.cvSetZero (image)
for i in range (count):
# draw all the points
cv.cvCircle (image, points [i], 2,
cv.cvScalar (0, 0, 255, 0),
cv.CV_FILLED, cv.CV_AA, 0)
# start the line from the last point
pt0 = points [hull [-1]]
for point_index in hull:
# connect the previous point to the current one
# get the current one
pt1 = points [point_index]
# draw
cv.cvLine (image, pt0, pt1,
cv.cvScalar (0, 255, 0, 0),
1, cv.CV_AA, 0)
# now, current one will be the previous one for the next iteration
pt0 = pt1
# display the final image
highgui.cvShowImage ('hull', image)
# handle events, and wait a key pressed
k = highgui.cvWaitKey (0)
if k == '\x1b':
# user has press the ESC key, so exit
break
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