Is there any software for Mac which watches out head and focus a window that is in a specified monitor based on our head angle? I'm using 3 monitors at the same time and hitting cmd + tab is always the pain.
You may be able to craft your own solution with a combination of scripting software and assistive hardware.
Assistive hardware exists to track head movement. Most assistive hardware can be used to provide an input that can then be scripted via AppleScript or shell script.
A few examples are linked below. I have no experience with these tools but your goal appears possible.
HeadMouse® Extreme replaces the standard computer mouse for people who cannot use or have limited use of their hands when controlling a computer or alternative and augmentative communication (AAC) device. The HeadMouse translates natural movements of a user's head into directly proportional movements of the computer mouse pointer, so as the user moves their head the mouse pointer on the screen also moves.
The SmartNav 4 AT is a total hands-free mouse solution. With built-in Dwell Clicking Software and a free On-screen Keyboard created by Lake Software. The AT package is used successfully by people with ALS, spinal cord injuries, muscular dystrophy, and other special needs.
One Switch sell a wide range of assistive hardware and link to associated software.
The following list details a number of different styles of head, mouth and eye operated controllers. Most of these are for PCs and Apple computers, but there are alternatives for games consoles too. Some of these devices are very expensive, so it is always worth trying to track down some way of trying before you buy.
I haven't heard of any such software before, though it certainly may exist.
However, there are a few problems:
- It would go crazy every time you turn around or look away from your current monitor: it's probably something you do much more often than you'd realize without the camera tracking your head and doing stuff based on its position.
- Most head-tracking software isn't sensitive enough to determine where your eyes are; that is, you'd have to turn your head completely toward the display for it to switch to that display, which would get annoying after a while because you'd have to exaggerate the head motion each time.
Essentially, if you wanted it to be accurate enough to determine what you're actually focusing on, you'd have to go into eye tracking, which can be messy and not altogether accurate with a built-in camera that wasn't necessarily meant for that sort of thing.
In any case, what you're looking for probably isn't possible with the iSight camera and would require some extra hardware (Graham Miln has given you some options).
That said, you may want to look at the Leap Motion Controller, which has a fairly robust set of applications that probably has something like this (so, you'd gesture toward the display you want and it would switch), but it's probably not faster than CMD+Tab (though you wouldn't have to cycle through all of your running applications).
If that doesn't work (or you don't want to buy an $80 motion tracking device), there's always Better Touch Tool, which you could use to set up a few shortcuts (or trackpad/mouse actions) to switch displays for you.