Using Get Control Rotation YAW, are these correct?
0.0 - East
90 - South
180 - West
270 - North
That would make World +X East, -X West. -Y North, +Y South?
1 Like
it can be whatever you want. Its not built into the engine. Scale isn’t built into the engine, you can work at almost any scale you want. There isn’t a world, so how could there be directions?
Is there something that you were referencing to know directions?
I went with -Y as North because I was using Character Yaw as my baseline
Please note that skeletal meshes coming from Maya, for example the default Blue Guy, has a 90 degree offset and faces +Y by default until you correct it in the component transform. The character class should have an arrow showing you forward, which should be +X.
I suggest not trying to use any other direction as the built in Blueprint library expects +X as forward vector, +Y as side vector and +Z as up vector (as previously mentioned).
For simplicities sake I can see why you would use +X as north, 0.0 degrees Yaw is on the +X axis. In the real world that means East but I guess in the end it doesn’t really matter much, this question was so I could set up a compass using my characters yaw rotation, which I have already done. It’s easy for me to change the letters , I already have the range values for each direction, all they do is set a string variable to whatever letter I assign them
That should be perfectly fine. I didn’t think you literally meant north, as in using a compass. 
Funny, I was looking for an answer to this to name meshes and reference docs, but it just hit me that it is better to just go with ExteriorWall+X 
Stupidity attack
YES
Importing a real point cloud with correct coordinates result:
+X East, -X West. -Y North, +Y South
I think this is important for when you are simulating geolocated sunlight. Did you work out which axis is North?
1 Like
Which axis is “north” depends entirely on your code and assumptions and input data, not on the engine.
If you have built a model of the world that puts East along X and North along -Y, then that’s what your sunlight shader and general logic should assume. (Also note: Unreal Engine uses left-handed interpretation of coordinates, like a compass, not right-handed, like you’d typically draw a unit circle!)
Another way to think about this: “When a character controller has a yaw of 0, and moves straight forward, which axis does it move along?” (IIRC, It moves along the X axis.) Now, asking yourself “Which direction do I want a character controller to move when it has 0 yaw?” will answer “what cardinal direction should I make the X axis correspond to?”
This whole subject makes 0 sense. In all possible sense.
NORTH is a human construct derived from the earth’s natural magnetic field.
So much so that we have True North and Magnetic North just to confuse navigational matter further.
In an environment that you define, how can we tell you what You made your cardinal directions out to be?
You can adjust the rotation of the sun/sky actor to match taste too, so it wouldn’t make much sense even when using cookie cutter pieces…
Yes, I’m doing that.
lol, dig this thread.
But if using Ultra Dynamic Skys simulate mode ( like I am) it states in the readme by default +X is North. but of course, can be adjusted clockwise for one’s needs!
I feel like this is a topic that could live forever.
In kung fu we always began facing North.
In that sense X+ is North.
Why? For one it means you’re paying attention, you’re thinking, you’re aware of the world and where you are and nature. Connecting with nature.
Another reason might be if it’s the morning do you want to face East with the sun in your eyes? Or West at sundown? Not a good way to begin. In Samurai 3, the opponent fell because he wasn’t aware of where the sun was and the hero was. He used it to his advantage, so the other guy couldn’t see.
Maybe you are the needle and the most natural thing you can do is face north. It can represent the path of least resistance.
And if X+ is North, by default the sun is somewhat South. Does that mean we’re in the northern hemisphere? Maybe it’s an alien planet where the equator is too hot and so everyone settles toward the poles. They say in the north pole the sun only rises and sets once a year. Where does it set from? How do you measure direction if you’re at the north pole? There is no East or West, only South.
I had no intention of writing all this, but it’s kind of fascinating.
It’s not as unreasonable a question as you posit. Some 3D software - probably almost exclusivley CAD software - have a pre-assigned compass to its 3D axis. I can tell you for certain that Revit does. I think AutoCAD might too…
Its not an environment (like earth) where someone long ago decided to call it north and it stuck.
You literally make your own cardinal conventions in any and all 3d applications - since always - given that the purpose of 3rd is to generate whatever you want to represent however you want it represented.
So, no. Even in revit someone went in and said “point that way” and you can likely edit that setting.
But more likely, what you have is cardinality rather than a compass.
X/Y/Z and whatever they point to on negative or positive side.
Generally you even get to make up what is up and what is down since the axis can be shifted to taste (in some programs anyway).
Its the whole concept behind left handed and right handed environments - ei Unreal and Blender which are exactly left and right coordinate driven…
@MostHost_LA, no. Just… no. 
You’re thinking of the freedom you have in UE and applying it unilaterally. I am telling you right now, that isn’t always the case - and the more specialised the software, the less likely these sorts of things are to be freely changeable.
Using the Revit example, you do not just get to rotate the axis. If you need to move true north, technically you rotate the entire bloody world (I am not kidding here 
) to suit Revit’s axis. You don’t move Revit’s axis to suit the world - Y is always North; X is always West.
Programs like that are used for fairly complex solar analysis studies and the like. So I understand why their devs don’t let end users mess with its internal coordinate system. So that, and the fact you can export from Revit to Unreal renders the question reasonable. Just because the answer is “it’s redundant/irrelevant/immaterial” doesn’t make the question so…
Maybe you don’t know how to use revit, but you can literally just project the north axis to whatever angle you want.
In real world (and paricularly in science based applications or archviz) application (like I already mentioned but you just think you know better) you have True and Magnetic North.
Both conventions can vastly differ for specific locations.
In essence, even on Earth North means next to nothing since one first has to define which convention to adhere to.
Dude, I’ve been using Revit for 25 years… It sounds to me like you’ve never even opened it.
What I said above is 1000000% correct. In Revit, Y is always north. X is always west. Argue that point all you like. You will be wrong if you do though.
There’s a Sun Position Calculator default plugin, so you could say that’s the closest thing to a default preference (North is X+). But there’s also a North Offset built into it so it’s easy to change.
Second thought, if you bring in a heightmap for a landscape, is that using X+ for up/north? I’ve never double checked.
Landscapes can rotate as well, so its also inconsequential.