So I have been thinking of an idea for a motion tracking airsoft gun (that shoots pretty much anything "moving"). I have all of the design pretty much done (inside my head) except for what software I could use for the motion tracking part.. I understand these pieces of software are absoulty massive and would have to run on my laptop. Thus creating the need for I/O (but I can worry about that later it doesn't scare me that much). My problem is that I am looking for a free program that can analyze realtime input from a webcam or something and output cordinates. I have seen projects similair using "pixy" but I don't exactly want to drop another $74.99 on this project the stepper motors are pretty much all i really want to stomach at this point in time. I have seen projects like "http://www.instructables.com/id/Face-detection-and-tracking-with-Arduino-and-OpenC" but i don't really want to worry just about faces (It's not meant to shoot peoples eyes out!) I honestly just want to worry about movement in all reality at this point in time it almost looks easier to beg my physics teacher to let me use the schools "matLab" but I really don't want to do that. I imagine it can't be that hard to find a free piece of software to just track movement because hell if it can identify faces for free. Why can't there be a piece of software that just looks for differences in frames.
Why can't there be a piece of software that just looks for differences in frames.
What has this got to do with Arduino?
Is it just a rant about your inability to implement frame differencing?
Sorry for the rant like aspects been having computer issues (not arduino little stressed). This is ardunio related because it will be used in an arduino project hence the posting in "project feasibility" . I am really looking forward to feedback from you guys on possible ideas sorry for the ranting aspects. 
is writing the code yourself an option?
because it doesnt sound very hard to just use a computer's webcam and capture the video stream then analyse the stream for "moving objects" by checking changing pixels and set thresholds, probably 1 or 2 afternoon's time worth of coding if you are really in the zone
Programming isn't out of the question but i'll need pointing in the right direction as in like libaries and possible place to start. I don't need any coding done for me I just need some documentation on the very basics.
OpenCV
Ok cool i was kinda eyeing that but wasn't sure on how "programmable" thank you guys for the help I can't wait to get started.