Nether Spawns: Y Axis Relevant?

Question

Alright, I have two spawns in the Normal World:

one at: (which I will call Main)

x: -22
y: 65
z: 261

and another at: (which I will call Tower)

x: 17
y: 244
z: 296

Yes, I know that I should have a distance between the two portals of 1024 on either the x or y axis, but shouldn't the scan in the Nether pick up the closest portal within a 128 block range?

Get this...

Main translates to:

x: -2.75
y: 8.125
z: 32.625

and Tower translates to:

x: 2.125
y: 30.5
z: 37

... in the Nether. Now, in the Nether, I have constructed two portals:

One at: (which I will call nMain)

x: -2
y: 60
z: 31

and the second at: (which I will call nTower)

x: 2
y: 67
z: 36

Now, Main links to nMain and Tower links to nTower, yet both nMain and nTower link to Main. I can't get nTower to link back to Tower, which is what I want.

I have:

Tower -> nTower
Main  -> nMain

nMain
      } Main
nTower

..but I want:

Tower <-> nTower
Main  <-> nMain

So, here is my question. Have I configured my Nether portals incorrectly in some way (as in, is Y-Axis now relevant?), or have I simply placed my Normal World portals far too close together (which would suck)?

Thanks everybody!

Answer 1

While converting between Overworld and Nether coordinates, only X and Z are scaled by 8, y remains the same (in your calculation y is also divided by 8). This is not the problem, actually.

Here is how it works: When you enter a portal, the game calculates the ideal point where you should appear on the other side (by scaling X and Z with 8). Then it searches the closest portal to that ideal point.

If you do the calculations backwards (Nether -> Overworld coordinates), you get that entering nMain will try to go to here in the Overworld (let's call it nMainOut):

x: -16
y: 60
z: 248

...and 'nTower' will go to here (let's call it nTowerOut):

x: 16
y: 67
z: 288

The game searches the closest portal to those 'out' points. For both of these 'out' points the closest portal happens to be the Main portal at:

x: -22
y: 65
z: 261

The distance between points is euclidean distance, that is

distance = sqrt( (x1-x0)^2 + (y1-y0)^2 + (z1-z0)^2 )

If we calculate the distance between nTowerOut and Main we get 55.1

If we calculate the distance between nTowerOut and Tower we get 177.2

That is why nTower goes to Main.

With your current setup, I'm afraid it is not possible to build a Nether portal that goes to your Tower portal, unless you move the Main portal down near bedrock and also move nTower near the top of the Nether.