How To Determine if two vectors are inline for collision.

Hi there,
I want to make a function which will handle multi touch: pinch zoom and rotate camera.

I have determined that tbis is a tricky scenario. Both situations have (at times) positions which are approaching each other. The greatest difference is if they are approaching each other on the same line (will hit - pinch zoom in) or if they are approaching each other but will never hit each other as they are on opposite sides of the screen (rotate cam).

So, if I have two delta vectors, and two corresponding positional vectors.... How do I determine if these two will (most likely) hit each other or not?

Hmmmmm
Calculating.

 

To determine pinch/zoom you need to measure the distance between two touching points (using Vector3.Distance() perhaps) and compare it this frame to a previous frame distance value.

If it changes more than a threshold, you have started a pinch/zoom maneuver.

To determine two-finger rotation, you need to get the angle of the line between the two points (using Mathf.Atan2() perhaps) and compare it this frame to a previous frame angle value.

If that changes more than a threshold amount, you have started a rotation maneuver.