Help with dragging

Hi guys! Hope you can help me out with a small problem here.

Attached is the .fla. Im actually trying to make this small educational app that helps children learn to find the area of triangles (1/2 x length x height).

Right now I need to make 3 draggable anchor points so the teacher is able to drag the points to create different shaped triangles.

I have a grid on one of the layers.

Currently, my 3 anchors are given instance names (n1,n2,n3) and are given the following button actions

on (press) {
	startDrag("_root.n1",true);
}

on (release) {
	stopDrag();
}

The dragging works fine but I want the anchors to snap to the grid I created. How would I go about doing that?

I was thinking of make little small MCs on the grid points and using dropTarget to snap the anchors to them, but that would require many many small MCs on the grid points. Is there any easier and more effective way?

Thanks a lot dudes :azn: