pinch in/out in any point

Techniques
1

Hi,

I make multi touch 2D application.
My app has some geos and ortho camera, and I want to pinch in/out in any point and scroll position, almost the same touch designer’s Network Editor.

I use multi touch dat and set null comp as parent of all geos.
I succeeded scroll position and pinch in/out , but scale pivot in screen is different from center of two fingers.

I guess I have to change camera position and null position at sametime when I pinch in/out, but I have no idea.

Any ideas are greatly appreciated.
pinch.toe (6.43 KB)