I am developing a JavaScript multi-player game which I want to make multi touch compatible. When shopping for large multi touch overlays such as PQlabs G5 which espouses the capability of detecting up to 50 touch points simultaneously; I see they don't indicate the number of touch screen users that can be processed simultaneously in their features. If the answer is "it depends", what are the limiting factors?

  • 3
    Touch screens generally can't differentiate between different users, since the only kind of input they can detect is physically touching the screen. That means it's up to your interaction design to figure out how many users you could accommodate physically (50 fingers could mean 5 users using their whole hands or 50 users using one finger each)
    – Kit Grose
    Commented Jan 1, 2016 at 3:06
  • Can you make your question clearer?
    – Midas
    Commented Jan 4, 2016 at 16:30
  • As said by Kit, the screen itself can't do this. I've seen projects involving a Kinect to detect & recognise the different users.
    – Marcy
    Commented Jan 6, 2016 at 8:45

1 Answer 1


As Kit says in their comment the screen itself can't distinguish from 10 people using all five digits on one hand and 50 people using a single finger.

What you'll have to do is work out some way of grouping the touches into a single user's interaction. This could be proximity in distance - all touches within a couple of centimetres of each other are likely to be from a single user - however that doesn't help if people can move their hands past each others. It could also be proximity in time - if the touches are within (say) 500 milliseconds of each other then it's likely it's the same user.

A third alternative would be to have specific locations on the screen that the users touch (on screen controllers, avatars etc.). With this approach you "know" that all touches within this area are from a single user.

Making your game turn based so only one player is touching the screen at any one time might help - if only to allow them physical access to the screen - but this might not be compatible with the game modes you require.

Perhaps the best approach would be to use a combination of these.

  • Not just proximity. As it is a game that OP is referring to then I would assume that each player will have an avatar / on-screen controller of some kind. By specifying 10 users the system can then display 10 avatars / controllers, so you know if someone presses 'left' on controller 5 then that is being used by User 5.
    – JonW
    Commented Jan 6, 2016 at 10:55
  • @JonW - I was going to add something about touching on specific places on the screen, but I thought I'd leave it more general - but that's also a possibility.
    – ChrisF
    Commented Jan 6, 2016 at 10:57
  • Another idea is to make the game for 5 users, each with their own iPad, which have 11 points of touch. Commented Mar 7, 2016 at 19:07

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