NOTE: This program only works on Linux. You need to have xdotool installed.

This is a simple opencv program that uses thresholding to track
an object visible to the webcam and controls the position of the 
mouse pointer based on the position of the cetroid of the thresholded
image.

Calibration:
So this program will require you to reacalibrate everytime you use it
unless lighting conditions are identical. There are three calues you can
tweak. Hue, Saturation and Luminance.

In the main code, comment out the mousemove function call in the main function, (You'll find it near the bottom).
then compile and run the program. Manually fiddle around with the track bars until only
the object of interest is visible in the thresholded image. Record these trackbar
values. Now go to the main function in the program and change the upper and lower
thresholds for the HSV values. 
Uncomment the mousemove function, compile and run again. Now you can control the
movement of the mouse pointer on screen using your object.

I'll add in an automatic thresholding function later. When I have the time.