Cannot figure out multitouch

[Keith]

I have added the multitouch object to my frame, enabled multi touch for the frame and now what? I expected that my existing objects would react to touches on the existing User clicks the left button events. What am I not doing that I should?

[Anders]

Whenever you are only touching the screen one place it will work as if you were using your mouse on the PC. Whenever you have multiple fingers touching the screen then Xmouse and Ymouse will still only work for the first finger that was put in the display. You can instead get the other touches through expressions and conditions in the Multitouch object.

[Keith]

How would I translate that easily into a continuos "If the Touch X, Y was on a particular object"?

How does this impact non-square objects and irregulars like characters with alpha channels? Is multi touch really not useful in these scenarios?

[LB]

You could have 1-pixel objects for each touch and check for overlapping

[Keith]

Here is more detail for the benefit of others that may look to this for an answer since I found that the docs are almost non-existent and the answers here more point you in the right direction than answer the question:

The basic solution I used was to put an Always event in my Game that places existing off-screen objects at the X/Y location of the first two "touches" in the Multi Touch object. I did this using the following:

#1

Added two objects that are simply circles the size of a typical finger tip named:

Object Multi Touch 1
Object Multi Touch 2

At Start of Frame set them to "Make Invisible" so they still work just are not apparent to the user. For my App I only care about the first two concurrent Multi-Touches, but you could expand this to support the possible 10 very easily.

#2

I don't care about get the X,Y if users slide their fingers around the screen for my app. I only care about the touch end points so here is how I register them:

A touch has ended, number 0 - Set X Position of Multi Touch 0 - to XTouch( "Multi Touch Object", 0 )
A touch has ended, number 0 - Set Y Position of Multi Touch 0 - to YTouch( "Multi Touch Object", 0 )
A touch has ended, number 1 - Set X Position of Multi Touch 0 - to XTouch( "Multi Touch Object", 1 )
A touch has ended, number 1 - Set Y Position of Multi Touch 0 - to YTouch( "Multi Touch Object", 1 )

If you wanted the X/Y points to register always you going literally just use the Set X Position etc. in your Always.

#3

Since I only care about end points, I want to push my end points offscreen constantly. To do this I do the following:

// This puts each Multi Touch point object offscreen again since the Multi Touch points 0-9 (I'm only caring about the first two 0 and 1 ) X,Y coords could be constantly updating as the user slides their fingers around the screen.
Always - Set Position at - Object Multi Touch 1 - -500, -500
Always - Set Position at - Object Multi Touch 2 - -500, -500

#4

Since I want to test collisions of end points with other objects, I simply use the standard cick event for handling mouse/first touch events regularly:

User clicks with left button on "Some target object"

OR

"Object Multi Touch 0" is overlapping "Some target object"

This approach game be the desired effect of capturing the first two taps on the screen that may occur concurrently and determining if they were taps on particular objects on the screen itself while disregarding any dragging or sliding of the fingers.

[Ortmon]

Excellent Keith!
Thanks for sharing this Good luck with your projects!