Mr B, can you explain how to convert between Nether and overworld coordinates? I found out when using TeleportSigns that they're on different systems, but I don't know how great the divergence is, in terms of numbers.
I honestly don't know the answer to that, but you shouldn't have to convert any coordinates between Nether and surface. Instead, record the coordinates in each world separately. Just follow the process in the first post so that you have a linked pair of portals in the correct locations in both worlds, and then do as mantissa128 said earlier:
Quote from mantissa128 »
Using MGPS, the process is the same - divide the location difference in blocks by 8, then add to your Nether coordinates and go geocaching!
I'm not familiar with the TeleportSigns mod, so I can't really help with that. But if it is able to display coordinates like Sign Tags, then you can record coordinates for each world. Just remember to ignore elevation when you record coordinates, because elevation doesn't matter for linking portals.
edit: You posted while I was writing this, and that method does seem to work, except you divide coordinates in the real world by 8 to get the coordinates in the Nether. I guess you can just directly convert coordinates. I feel stupid now. I've been tracking the coordinates for each world separately, then dividing the difference by 8. I'll have to test further.
Quote from petrus4 »
So if I take the three coordinate numbers of a gate's position in the real world, and then divide each number by 8, will that give me the coordinates in the Nether? I apologise if that sounds stupid; mathematics is not a strong point of mine. If that is correct, however, that should be quite simple.
I'm not familiar with the TeleportSigns mod, so I can't really help with that. But if it is able to display coordinates like Sign Tags, then you can record coordinates for each world. Just remember to ignore elevation when you record coordinates, because elevation doesn't matter for linking portals.
It does. It just displays the coords statically on each sign, is all; so I have to put signs all over the place if I want to be able to compare locations. It's a bit annoying, but I don't mind too much. I enjoy tree farming. :wink.gif:
edit: You posted while I was writing this, and that method does seem to work, except you divide coordinates in the real world by 8 to get the coordinates in the Nether. I guess you can just directly convert coordinates. I feel stupid now. I've been tracking the coordinates for each world separately, then dividing the difference by 8. I'll have to test further.
I've since reverted this save to a pre-Halloween update backup which I had, and regenerated the Nether. The initial Hell build I had was absolutely horrible, but my overworld gate room works a treat, now. So no complaints there, but I'm still interested in this, in terms of trying to figure out how portals work.
Gate coords in the Nether are 3, 43, 44
Gate coords in the Gateroom are 4, 53, 303
Nether number was taken by knocking a block out of the gate, and then placing the sign on the center block of the gate. Gateroom number was taken by clicking the sign on the inside of the gate, which attached the sign to the outer edge of the gate; so I am not exactly sure which of those two numbers is correct.
The second number being the Z axis, implies that my gate is 10 blocks higher in the gateroom (although it is still around 18 blocks below sealevel) but I can remember you saying that Z axis is apparently irrelevant, so I will disregard that.
The one number difference which I cannot account for is the last one. The distance from the gate to 303 Y in the Nether is, as expected, quite large. Does this indicate a large variance in the position of the gateroom gate, relative to where it should be, in order to be properly aligned?
Gate coords in the Nether are 3, 43, 44
Gate coords in the Gateroom are 4, 53, 303
Nether number was taken by knocking a block out of the gate, and then placing the sign on the center block of the gate. Gateroom number was taken by clicking the sign on the inside of the gate, which attached the sign to the outer edge of the gate; so I am not exactly sure which of those two numbers is correct.
The second number being the Z axis, implies that my gate is 10 blocks higher in the gateroom (although it is still around 18 blocks below sealevel) but I can remember you saying that Z axis is apparently irrelevant, so I will disregard that.
Note that the Y axis is the vertical one, the one that doesn't matter. X and Z positions are both important. And a sign on the outside of the gate will be off by one or two blocks (but there's a bit of uncertainty in the positioning anyway, since the gate itself is two blocks wide -- in theory that could cause some weird behaviour if you happen to get it spanning a chunk boundary, although I haven't tested that myself).
So assuming the two coordinate systems meet at 0,0 (which I'm not entirely certain about), your gateroom portal would be trying to establish a portal at approx 0, 53, 38 in the Nether (assuming those were XYZ). So it's close, but not quite right. Both the "real" and "expected" positions are within the same Nether chunk, though, so this still ought to be work fully two-way as it stands.
So assuming the two coordinate systems meet at 0,0 (which I'm not entirely certain about), your gateroom portal would be trying to establish a portal at approx 0, 53, 38 in the Nether (assuming those were XYZ). So it's close, but not quite right. Both the "real" and "expected" positions are within the same Nether chunk, though, so this still ought to be work fully two-way as it stands.
I'm trying to work out where the 38 comes from. I subtracted 44 from 303 and got 259. I then divided that by 8, and got 32, rounded off. So are the correct coords 0, 53, 32, or is my formula incorrect?
I'm trying to work out where the 38 comes from. I subtracted 44 from 303 and got 259. I then divided that by 8, and got 32, rounded off. So are the correct coords 0, 53, 32, or is my formula incorrect?
Formula is wrong. Divide overworld coordinates by 8 to derive Nether coordinates, but ignore elevation. I have no idea how elevation is determined for portals since I just place them where I want them to be. Do the reverse in the Nether; multiply by 8 to derive overworld coordinates. I just checked all my portals' coordinates, and they all follow this rule. However, all of my portals are close together, and I only have 8(4 linked pairs), so I need more data.
So when you posted:
Gate coords in the Nether are 3, 43, 44
Gate coords in the Gateroom are 4, 53, 303
The expected coordinates for the Nether portal would be: 0, (?), 38(303/8=37.875). Numbers are approximate, as I don't know how rounding is handled. Actually, that Nether portal should link to a different location in the overworld, but I think Notch's post-Halloween update increased the margin for error.
In case it's helpful, I'll just post coordinates of all my portals.
I'm fairly sure that the "desired" Y coordinate between the two dimensions are mapped 1:1. But the game will vary this as well when it tries to locate a safe spot to place the created portal. Even so, a portal near bedrock on one side will tend to create a portal near bedrock on the other side (provided that there's a landing spot). Portals near the surface will probably be better matched at first, though, since there's more open space and less chance of a obstruction at the desired coordinates.
Best guess, but I haven't done any testing on this, is that it first searches for any existing portals in the same chunk as where it's supposed to land, and failing that searches outwards in a sphere from the desired coordinates and creates a new portal in the closest direct-line location that's large enough and has a safe floor. (Although since some people have reported flying portals, it's likely that it only needs one or two blocks of floor, and it replaces them as part of creation.)
I'm fairly sure that the "desired" Y coordinate between the two dimensions are mapped 1:1. But the game will vary this as well when it tries to locate a safe spot to place the created portal. Even so, a portal near bedrock on one side will tend to create a portal near bedrock on the other side (provided that there's a landing spot). Portals near the surface will probably be better matched at first, though, since there's more open space and less chance of a obstruction at the desired coordinates.
Best guess, but I haven't done any testing on this, is that it first searches for any existing portals in the same chunk as where it's supposed to land, and failing that searches outwards in a sphere from the desired coordinates and creates a new portal in the closest direct-line location that's large enough and has a safe floor. (Although since some people have reported flying portals, it's likely that it only needs one or two blocks of floor, and it replaces them as part of creation.)
I think this is true, i've noticed that mountain top portals will appear higher and bedrock portals will appear lower in the Nether.
What I'm not sure about is whether or not the game will search the entire Nether vertically before moving to a "closer" horizontal safe location.
If there is a safe spot 50 blocks vertically (which would maintain a functional 2 way portal) and another safe spot 10 blocks horizontally (which will begin the portal problem) will it choose to move horizontally?
Hopefully the portals exhaust all possible vertical locations before moving horizontally but this would be tough to confirm.
Formula is wrong. Divide overworld coordinates by 8 to derive Nether coordinates, but ignore elevation. I have no idea how elevation is determined for portals since I just place them where I want them to be. Do the reverse in the Nether; multiply by 8 to derive overworld coordinates. I just checked all my portals' coordinates, and they all follow this rule. However, all of my portals are close together, and I only have 8(4 linked pairs), so I need more data.
I would view your success as reason for optimism, personally. Portals that are close together, are the type which have been most problematic, at least for me, and for some others I've seen as well. My main interest is in seeing how fine grained the system can be. I'm not expecting more than one portal per overworld chunk, for hopefully obvious reasons; but at least two portals per Nether chunk should be feasible, and maybe even three.
The expected coordinates for the Nether portal would be: 0, (?), 38(303/8=37.875).
I appreciate those numbers, but unfortunately I already went ahead and built another portal at the coords that I reached with the bad formula. Still, the difference is only 6 blocks, (32 vs 38) so it shouldn't be a huge issue in this case, as I am not planning on building a second portal close to that one in the overworld, at least not at any time reasonably soon. I should probably do some tests with nearby portals, to see how robust the linking is. I will also have to ensure that I use the other formula next time.
but I think Notch's post-Halloween update increased the margin for error.
It did. That's actually the main problem at the moment. My experience suggests that the search radius is at least 32 blocks, and other people's experiences imply that it could be much larger. For those of us doing the work of manually setting coordinates, that is not a problem, but unfortunately, the best guess scenario is what most people rely on.
BTW this glitch can be used for free obsidian. Enter portal A and come out portal C then enter portal C and come out portal D, mine the obsidian from Port D and walk back to port A, then repeat.
I'm fairly sure that the "desired" Y coordinate between the two dimensions are mapped 1:1. But the game will vary this as well when it tries to locate a safe spot to place the created portal. Even so, a portal near bedrock on one side will tend to create a portal near bedrock on the other side (provided that there's a landing spot). Portals near the surface will probably be better matched at first, though, since there's more open space and less chance of a obstruction at the desired coordinates.
Best guess, but I haven't done any testing on this, is that it first searches for any existing portals in the same chunk as where it's supposed to land, and failing that searches outwards in a sphere from the desired coordinates and creates a new portal in the closest direct-line location that's large enough and has a safe floor. (Although since some people have reported flying portals, it's likely that it only needs one or two blocks of floor, and it replaces them as part of creation.)
I think this is true, i've noticed that mountain top portals will appear higher and bedrock portals will appear lower in the Nether.
What I'm not sure about is whether or not the game will search the entire Nether vertically before moving to a "closer" horizontal safe location.
If there is a safe spot 50 blocks vertically (which would maintain a functional 2 way portal) and another safe spot 10 blocks horizontally (which will begin the portal problem) will it choose to move horizontally?
Hopefully the portals exhaust all possible vertical locations before moving horizontally but this would be tough to confirm.
Then my question is why when I build a portal way above in the nether, and it takes me to a cave even though when I dig up sometimes I find tons of land where the portal could have gone.
Also I am wondering why sometimes people just find portals that they never created. As in say a player creates portal D and C, and they link to eachother, and they find portal A, a portal they never created.
Also I am wondering why sometimes people just find portals that they never created. As in say a player creates portal D and C, and they link to eachother, and they find portal A, a portal they never created.
There has been some speculation, that a portal is created on player death in the Nether, at the point where the player died. Notch may have implemented that, to try and ensure that people have at least some chance of getting their equipment back.
This is pure speculation, but it is also possible that the system occasionally tries to create duplicate portals, which have a closer overworld correspondence with the Nether location that is being asked for, as well; but that for some reason, the player is still only sent through the portal they themselves created. Such a duplication effect would most likely occur when the player goes to leave the Nether.
Also I am wondering why sometimes people just find portals that they never created. As in say a player creates portal D and C, and they link to eachother, and they find portal A, a portal they never created.
There has been some speculation, that a portal is created on player death in the Nether, at the point where the player died. Notch may have implemented that, to try and ensure that people have at least some chance of getting their equipment back.
This is pure speculation, but it is also possible that the system occasionally tries to create duplicate portals, which have a closer overworld correspondence with the Nether location that is being asked for, as well; but that for some reason, the player is still only sent through the portal they themselves created. Such a duplication effect would most likely occur when the player goes to leave the Nether.
Portals spawned on death? I'll have to test this now...
I don't know yet.
These are a good questions and i've experienced those problems before.
Personally i consider extra portals to be the real portal bug because they seem, so far, to be illogical actions performed by the portals.
One of my first portals would spawn an extra portal somewhere within ~200 blocks every time i used it but still acted as a 2 way portal... I adjusted the location of the Nether portal slightly and the extra portals stopped spawning.
Those extra portals appeared even though i never entered or exited them plus They appeared at distances and in directions that didn't make any sense.
At first i thought these were the so called "natural portals" but they stop spawning once all your portals are properly linked so they are somehow connected to the same issue of safe spots and Nether obstructions.
Portals getting spawned on death is a real bug(?). I've managed to get them quite a few times, they really stick out with a Cartograph of your map.
It's basically the result of the game making you exit the Nether on death the same way it normally swaps dimensions: with the Portals. Your point of death is treated as the entry Portal, and an Exit Portal is generated at the corresponding spot in the Overworld before you are moved back to spawn.
You can test this by entering the Nether, picking a random direction and moving that way for a significant distance. Then get killed by whatever means (Ghast, lava, Zombie Pigman, burning.... so much choice!). Now you should see a random chunk, with a portal directly at the centre (unless it spawned underground), when you render your map with Cartograph.
At first i thought these were the so called "natural portals" but they stop spawning once all your portals are properly linked so they are somehow connected to the same issue of safe spots and Nether obstructions.
Notch has fairly obviously tried to come up with some AI to handle portal generation, for those of us who aren't willing/able to wade into (basic) Cartesian mathematics. The broad concept is relatively solid, but the devil is always in the details. He also seems to have tried to build in the assumption that players will usually not build portals in safe/intelligent areas themselves, but rather that the player's creation of a portal should be interpreted as a general statement of, "I want to go to the Nether," and then for the system to take over and completely link/generate viable portals in both worlds, automatically.
I think he is doing a little too much work. There should be an assumption that whichever portal that the player builds is fine, (and he could, and perhaps should, write code to detect if a gate has been built by a player manually placing obsidian, if such is possible) and therefore that the system only has to worry about making sure that the portal at the other end is viable.
I would also suggest the idea of an interface which could let players who were so inclined, enter in their own coordinates to re-orient portals. The game could then check the provided coords, and if they are considered a closer match than what the game itself has attempted to provide, the game should then move the gate to said coords, without the player having to manually build another gate. This would take the most laborious element out of manually fixing malfunctioning gates.
Personally, I'd rather portals didn't try to be clever about moving around. Maybe allow it to shift Y position (up/down) to get somewhere "safe" for the very first portal, but after that it should just spawn in the "correct" corresponding position, regardless of what else is there at the moment (with maybe a small concession for lava -> netherstone or obsidian, otherwise the player will be trapped if they didn't bring a bucket). It's not hard to dig your way out if the portal spawns into solid rock, after all.
I would, though, like it to keep the current behaviour of happily linking back to a portal that's at the right XZ coords but has a completely different Y. That's very handy to get from my sealevel base to my bedrock mining zone, while staying on the level...
Portals getting spawned on death is a real bug(?). I've managed to get them quite a few times, they really stick out with a Cartograph of your map.
It's basically the result of the game making you exit the Nether on death the same way it normally swaps dimensions: with the Portals. Your point of death is treated as the entry Portal, and an Exit Portal is generated at the corresponding spot in the Overworld before you are moved back to spawn.
You can test this by entering the Nether, picking a random direction and moving that way for a significant distance. Then get killed by whatever means (Ghast, lava, Zombie Pigman, burning.... so much choice!). Now you should see a random chunk, with a portal directly at the centre (unless it spawned underground), when you render your map with Cartograph.
Personally, I'd rather portals didn't try to be clever about moving around. Maybe allow it to shift Y position (up/down) to get somewhere "safe" for the very first portal, but after that it should just spawn in the "correct" corresponding position, regardless of what else is there at the moment (with maybe a small concession for lava -> netherstone or obsidian, otherwise the player will be trapped if they didn't bring a bucket). It's not hard to dig your way out if the portal spawns into solid rock, after all.
I would, though, like it to keep the current behaviour of happily linking back to a portal that's at the right XZ coords but has a completely different Y. That's very handy to get from my sealevel base to my bedrock mining zone, while staying on the level...
In mathematical illustrations of two-dimensional Cartesian systems, the first coordinate (traditionally called the abscissa) is measured along a horizontal axis, oriented from left to right. The second coordinate (the ordinate) is then measured along a vertical axis, usually oriented from bottom to top.
However, in computer graphics and image processing one often uses a coordinate system with the y axis pointing down (as displayed on the computer's screen). This convention developed in the 1960s (or earlier) from the way that images were originally stored in display buffers.
For three-dimensional systems, mathematicians usually draw the z axis as vertical and pointing up, so that the x and y axes lie on an horizontal plane. There is no prevalent convention for the directions of these two axes, but the orientations are usually chosen according to the right-hand rule. In three dimensions, the names "abscissa" and "ordinate" are rarely used for x and y, respectively. When they are, the z-coordinate is sometimes called the applicate.
I prefer to speak of the z axis referring to the vertical dimension, personally; but I don't know whether it's a "potayto/potahto," issue or not. Z is apparently vertical primarily outside of computer-related usage.
Thank you very much for this guide. Fortunately I haven't had a broken portal yet, but I only have one world with with only two portals so I know I will eventually run into this problem. Nice to know how to fix it when it does happen.
Incidentally, Notch has added coordinates to the F3 debug screen, so it's even easier to get these portals aligned (you don't need to download an extra program). Just remember: the X and Z coordinates in the Nether should be 1/8th of the values in the overworld. (The Y coordinate doesn't matter, but technically it should be the same in both.)
I honestly don't know the answer to that, but you shouldn't have to convert any coordinates between Nether and surface. Instead, record the coordinates in each world separately. Just follow the process in the first post so that you have a linked pair of portals in the correct locations in both worlds, and then do as mantissa128 said earlier:
I'm not familiar with the TeleportSigns mod, so I can't really help with that. But if it is able to display coordinates like Sign Tags, then you can record coordinates for each world. Just remember to ignore elevation when you record coordinates, because elevation doesn't matter for linking portals.
edit: You posted while I was writing this, and that method does seem to work, except you divide coordinates in the real world by 8 to get the coordinates in the Nether. I guess you can just directly convert coordinates. I feel stupid now. I've been tracking the coordinates for each world separately, then dividing the difference by 8. I'll have to test further.
It does. It just displays the coords statically on each sign, is all; so I have to put signs all over the place if I want to be able to compare locations. It's a bit annoying, but I don't mind too much. I enjoy tree farming. :wink.gif:
I've since reverted this save to a pre-Halloween update backup which I had, and regenerated the Nether. The initial Hell build I had was absolutely horrible, but my overworld gate room works a treat, now. So no complaints there, but I'm still interested in this, in terms of trying to figure out how portals work.
Gate coords in the Nether are 3, 43, 44
Gate coords in the Gateroom are 4, 53, 303
Nether number was taken by knocking a block out of the gate, and then placing the sign on the center block of the gate. Gateroom number was taken by clicking the sign on the inside of the gate, which attached the sign to the outer edge of the gate; so I am not exactly sure which of those two numbers is correct.
The second number being the Z axis, implies that my gate is 10 blocks higher in the gateroom (although it is still around 18 blocks below sealevel) but I can remember you saying that Z axis is apparently irrelevant, so I will disregard that.
The one number difference which I cannot account for is the last one. The distance from the gate to 303 Y in the Nether is, as expected, quite large. Does this indicate a large variance in the position of the gateroom gate, relative to where it should be, in order to be properly aligned?
Note that the Y axis is the vertical one, the one that doesn't matter. X and Z positions are both important. And a sign on the outside of the gate will be off by one or two blocks (but there's a bit of uncertainty in the positioning anyway, since the gate itself is two blocks wide -- in theory that could cause some weird behaviour if you happen to get it spanning a chunk boundary, although I haven't tested that myself).
So assuming the two coordinate systems meet at 0,0 (which I'm not entirely certain about), your gateroom portal would be trying to establish a portal at approx 0, 53, 38 in the Nether (assuming those were XYZ). So it's close, but not quite right. Both the "real" and "expected" positions are within the same Nether chunk, though, so this still ought to be work fully two-way as it stands.
I'm trying to work out where the 38 comes from. I subtracted 44 from 303 and got 259. I then divided that by 8, and got 32, rounded off. So are the correct coords 0, 53, 32, or is my formula incorrect?
Formula is wrong. Divide overworld coordinates by 8 to derive Nether coordinates, but ignore elevation. I have no idea how elevation is determined for portals since I just place them where I want them to be. Do the reverse in the Nether; multiply by 8 to derive overworld coordinates. I just checked all my portals' coordinates, and they all follow this rule. However, all of my portals are close together, and I only have 8(4 linked pairs), so I need more data.
So when you posted:
The expected coordinates for the Nether portal would be: 0, (?), 38(303/8=37.875). Numbers are approximate, as I don't know how rounding is handled. Actually, that Nether portal should link to a different location in the overworld, but I think Notch's post-Halloween update increased the margin for error.
In case it's helpful, I'll just post coordinates of all my portals.
Surface ----> Nether
1. 142 & 143, 63, -260 (Home) ----> 17, 55, -31 & -32
2. 131 & 132, 18, -208 (Mine) ----> 15 & 16, 55, -26
3. 118, 67, -50 & -51(Spawn) ----> 14 & 15, 51, -6
4. 140 & 141, 111, -217 (Lava sphere) ----> 17, 94, -26 & -27 (Portal is the only entrance.)
Best guess, but I haven't done any testing on this, is that it first searches for any existing portals in the same chunk as where it's supposed to land, and failing that searches outwards in a sphere from the desired coordinates and creates a new portal in the closest direct-line location that's large enough and has a safe floor. (Although since some people have reported flying portals, it's likely that it only needs one or two blocks of floor, and it replaces them as part of creation.)
I think this is true, i've noticed that mountain top portals will appear higher and bedrock portals will appear lower in the Nether.
What I'm not sure about is whether or not the game will search the entire Nether vertically before moving to a "closer" horizontal safe location.
If there is a safe spot 50 blocks vertically (which would maintain a functional 2 way portal) and another safe spot 10 blocks horizontally (which will begin the portal problem) will it choose to move horizontally?
Hopefully the portals exhaust all possible vertical locations before moving horizontally but this would be tough to confirm.
viewtopic.php?f=35&t=93046&start=30
I would view your success as reason for optimism, personally. Portals that are close together, are the type which have been most problematic, at least for me, and for some others I've seen as well. My main interest is in seeing how fine grained the system can be. I'm not expecting more than one portal per overworld chunk, for hopefully obvious reasons; but at least two portals per Nether chunk should be feasible, and maybe even three.
I appreciate those numbers, but unfortunately I already went ahead and built another portal at the coords that I reached with the bad formula. Still, the difference is only 6 blocks, (32 vs 38) so it shouldn't be a huge issue in this case, as I am not planning on building a second portal close to that one in the overworld, at least not at any time reasonably soon. I should probably do some tests with nearby portals, to see how robust the linking is. I will also have to ensure that I use the other formula next time.
It did. That's actually the main problem at the moment. My experience suggests that the search radius is at least 32 blocks, and other people's experiences imply that it could be much larger. For those of us doing the work of manually setting coordinates, that is not a problem, but unfortunately, the best guess scenario is what most people rely on.
Then my question is why when I build a portal way above in the nether, and it takes me to a cave even though when I dig up sometimes I find tons of land where the portal could have gone.
Also I am wondering why sometimes people just find portals that they never created. As in say a player creates portal D and C, and they link to eachother, and they find portal A, a portal they never created.
There has been some speculation, that a portal is created on player death in the Nether, at the point where the player died. Notch may have implemented that, to try and ensure that people have at least some chance of getting their equipment back.
This is pure speculation, but it is also possible that the system occasionally tries to create duplicate portals, which have a closer overworld correspondence with the Nether location that is being asked for, as well; but that for some reason, the player is still only sent through the portal they themselves created. Such a duplication effect would most likely occur when the player goes to leave the Nether.
Portals spawned on death? I'll have to test this now...
I don't know yet.
These are a good questions and i've experienced those problems before.
Personally i consider extra portals to be the real portal bug because they seem, so far, to be illogical actions performed by the portals.
One of my first portals would spawn an extra portal somewhere within ~200 blocks every time i used it but still acted as a 2 way portal... I adjusted the location of the Nether portal slightly and the extra portals stopped spawning.
Those extra portals appeared even though i never entered or exited them plus They appeared at distances and in directions that didn't make any sense.
At first i thought these were the so called "natural portals" but they stop spawning once all your portals are properly linked so they are somehow connected to the same issue of safe spots and Nether obstructions.
viewtopic.php?f=35&t=93046&start=30
It's basically the result of the game making you exit the Nether on death the same way it normally swaps dimensions: with the Portals. Your point of death is treated as the entry Portal, and an Exit Portal is generated at the corresponding spot in the Overworld before you are moved back to spawn.
You can test this by entering the Nether, picking a random direction and moving that way for a significant distance. Then get killed by whatever means (Ghast, lava, Zombie Pigman, burning.... so much choice!). Now you should see a random chunk, with a portal directly at the centre (unless it spawned underground), when you render your map with Cartograph.
Notch has fairly obviously tried to come up with some AI to handle portal generation, for those of us who aren't willing/able to wade into (basic) Cartesian mathematics. The broad concept is relatively solid, but the devil is always in the details. He also seems to have tried to build in the assumption that players will usually not build portals in safe/intelligent areas themselves, but rather that the player's creation of a portal should be interpreted as a general statement of, "I want to go to the Nether," and then for the system to take over and completely link/generate viable portals in both worlds, automatically.
I think he is doing a little too much work. There should be an assumption that whichever portal that the player builds is fine, (and he could, and perhaps should, write code to detect if a gate has been built by a player manually placing obsidian, if such is possible) and therefore that the system only has to worry about making sure that the portal at the other end is viable.
I would also suggest the idea of an interface which could let players who were so inclined, enter in their own coordinates to re-orient portals. The game could then check the provided coords, and if they are considered a closer match than what the game itself has attempted to provide, the game should then move the gate to said coords, without the player having to manually build another gate. This would take the most laborious element out of manually fixing malfunctioning gates.
I would, though, like it to keep the current behaviour of happily linking back to a portal that's at the right XZ coords but has a completely different Y. That's very handy to get from my sealevel base to my bedrock mining zone, while staying on the level...
This is interesting and makes a lot of sense.
Thanks for the information!
viewtopic.php?f=35&t=93046&start=30
From Wikipedia:-
In mathematical illustrations of two-dimensional Cartesian systems, the first coordinate (traditionally called the abscissa) is measured along a horizontal axis, oriented from left to right. The second coordinate (the ordinate) is then measured along a vertical axis, usually oriented from bottom to top.
However, in computer graphics and image processing one often uses a coordinate system with the y axis pointing down (as displayed on the computer's screen). This convention developed in the 1960s (or earlier) from the way that images were originally stored in display buffers.
For three-dimensional systems, mathematicians usually draw the z axis as vertical and pointing up, so that the x and y axes lie on an horizontal plane. There is no prevalent convention for the directions of these two axes, but the orientations are usually chosen according to the right-hand rule. In three dimensions, the names "abscissa" and "ordinate" are rarely used for x and y, respectively. When they are, the z-coordinate is sometimes called the applicate.
I prefer to speak of the z axis referring to the vertical dimension, personally; but I don't know whether it's a "potayto/potahto," issue or not. Z is apparently vertical primarily outside of computer-related usage.
(Just checked: yes. In MC, south is +X, up is +Y, and west is +Z. This is a right-handed coordinate system...)