Calculating Bearing, Elevation, and Distance with vectors

[GhostMX]

So I'm working on a laser guided turret, but I've run into a small hitch. It seems that when I calculate the bearing and elevation between two vectors, they're global and not local to the object (No matter where I point, the bearing is absolute. Even if the rotation of the object changes, the bearing doesn't. Pointing at 0* points me at the north section of the map). This is the code to calculate (Thanks Shandolum)

@I X Y Z X2 Y2 Z2
@O Bearing Elevation Distance
V1 = vector(X,Y,Z)
V2 = vector(X2, Y2, Z2)
V3 = vecsub(V2 - V1)
Bearing = vecyaw(V3)
Elevation = vecpitch(V3)
Distance = veclength(V3)

If anyone can help me make those three outputs behave more like the beacon sensor's, that would be great.

I just poked around in the beacon sensor lua code, and found out how they calculate the bearing

local MyPos = self.Entity:GetPos()
local BeaconPos = self.ToSense:GetBeaconPos(self.Entity)
local DeltaPos = self.Entity:WorldToLocal(BeaconPos)
brng = DeltaPos:Angle()

Roughly translated: My position
Their position
Delta position by converting world coordinates of them to local coordinates to me
Output that angle

I guess WorldToLocal(Vector pos) would return MyPos - pos or pos - MyPos. I'm not sure how Angle() works though

I think I need to find the acos, so acos(vecdot(MyPos,Theirpos)) but that doesn't seem to work

Thanks!

[Syranide]

You need to use a gyroscope or one more GPS to get bearing and elevation to work properly, because they are relative to the direction of the object itself, which you can't know using just one GPS. (Which means that your current solution assumes that the prop is always facing the same direction and never rotates in any way)

Hmm, might need 3 GPSes in total when I think of it, but I'm not sure. (So you can extract both an up-vector, forward-vector and right-vector)

[GhostMX]

Just a thought

I'm in class now, but I think I might have solved it. I need to convert the world coordinates to local, like this

Pos = XYZ (world)
TPos = X'Y'Z' (world)

LPos = X+cos(Yaw)*Distance,Y+sin(Yaw)*Distance,Z (The projection to create our A vector
LTPos = X'Y'Z' - XYZ
LLPos = LPos - XYZ (to localize it)

So now we have two local vectors (relative to the position of the object)

arccos(vecdot(LTPos * LLPos / |LTPos|*|LLPos|)) (normalize and dot product them)

I hope this works, I was quite excited when I drew out the diagram. I have not yet confirmed it, but I will when I get back from class. If anyone wants, they can confirm it for me.

[1xinfusion]

bump.

[jakbruce2004]

bump

[IEF015]

Why

[kuro11]

The correct way of finding bearing elevation. (distance part was right). This is relative to the chip's forward vector.

N@Bearing
I@Xt Yt Zt
O@Bearing Elevation Dist
interval(1)
Target=vecsub(vector(Xt,Yt, Zt),extpos())
TargetN=vecnormalize(Target)
Br=acos(vecdot(extdirfw(),TargetN)/(veclength(extdirfw())*veclenght(TargetN)))
En=acos(vecdot(extdirup(),TargetN)/(veclength(extdirup())*veclenght(TargetN)))-90
Trt=acos(vecdot(extdirrt(),TargetN)/(veclength(extdirrt())*veclenght(TargetN)))
Tr=angnorm(Trt-90)
Bearing=(Br>0&Br<181?Br*sgn(Tr):0)
Elevation=En
Dist=veclength(Target)

The reason I post this here was I made a turret using the idea you had here, to do everything with vectors. However, that didn't work when the turret was tilted. So, with this, it will work right. Have fun.

[BManx2000]

There's a typo in your code, you have "veclenght" instead of "veclength".

Also, I tested this with a beacon sensor linked to a laser pointer reciever, and it works most of the time, but sometimes the bearing is wrong. Maybe you should look into it.

[Bull]

You do realize this is an almost year old thread?