3d ssget (Z axis)

Hello,
Was wondering if anyone has written their own version of (ssget) that takes into account the Z axis.
eg pass one point or two points 3D points and it only selects entities that pass through that point or 3d line (if two points passed).

I have one that works for simple entities (as well as block ins. pts) and polylines but it is not very efficient. So if I have a drawing with 50 polylines that all occupy the same X and Y space but each have different elevations - my routine will only select the plines that actually intersect with the 3d line I pass to it, but it can take 10 seconds or so to filter out the others.

thanks for any help.

 

if not misinterpreted,you would to find only value of z point ? is it true?

that pass through that point or 3d line (if two points passed).

polylines but it is not very efficient. So if I have a drawing with 50
polylines that all occupy the same X and Y space but each have different
elevations - my routine will only select the plines that actually intersect
with the 3d line I pass to it, but it can take 10 seconds or so to filter
out the others.