Get position

[Cristofer]

I am building a escort mission, where you are escorting a C130. I want a radio item (F10) that sends a text message about the C130 position relative yours. How exactlyis is that done?

 

I have tried getposition in do script, but I don´t seem to get it. I know nothing about scripting, so easy instructions please :)

 

Unit name of the C130: C130

Unit name of the player: Player

 

I have done a radio item add, that set flag 999 to true, or 1.

Then when 999 is true, the action is "do script". What exactly should I enter? (if it is possible at all)

[sea2sky]

local unitPos = Unit.getByName('My unit'):getPosition()

[Cristofer]

local unitPos = Unit.getByName('My unit'):getPosition()

 

Nothing happens.

[sea2sky]

Nothing happens.

 

try this:

 

local group = Group.getByName('Your unit group name')

local unitPos = nil

local units = group:getUnits()

if units then

unitPos = Unit.getByName(units[1]:getName()):getPosition()

end

[Cristofer]

No, nothing.

 

Where should I put the text?

 

My unit name is Player. The C130 unit name is C130.

 

Is this correct?

 

local group = Group.getByName('Player')

local unitPos = nil

local units = group:getUnits()

if units then

unitPos = Unit.getByName(units[1]:getName()):getPosition()

end

[sea2sky]

no, this is correct:

 

local group = Group.getByName('C130')

local unitPos = nil

local units = group:getUnits()

if units then

unitPos = Unit.getByName(units[1]:getName()):getPosition()

end

[Cristofer]

Still nothing. What exactly shall happen?

 

I want a text message to appear, with the C130 position

[sea2sky]

Still nothing. What exactly shall happen?

 

I want a text message to appear, with the C130 position

 

Ah, then you need to add an extra line (also, I assume 'C130' is a name of the group the unit belongs to):

 

local group = Group.getByName('C130')

local unitPos = nil

local units = group:getUnits()

if units then

unitPos = Unit.getByName(units[1]:getName()):getPosition()

end

trigger.action.outText("Position X is: "..unitPos.x.z, 5)

[Cristofer]

It works, thanks :)

 

But is it possible to use heading and range from your aircraft, or relative from bullseye? Now it says something like 0.5343242345 and that doesn´t say much to me :)

[sea2sky]

It works, thanks :)

 

But is it possible to use heading and range from your aircraft, or relative from bullseye? Now it says something like 0.5343242345 and that doesn´t say much to me :)

 

I knew that would be your next step :), but was kinda lazy to dig into the code... Ok, so here what you need to do:

 

- get position with the code I gave you

- get position of your own aircraft (same method, but use the name of your aircraft's group)

- convert positions above from Vec3 to Vec2 coordinates

- calculate a heading and distance using functions below

 

Conversion from Vec3 to Vec2 example:

local myVec2Position = {x = myVec3Position.p.x, y = myVec3Position.p.z}

 

These functions will calculate distance and heading between two positions respectively using Vec2 positions:

 

function GetDistance(Vec2a, Vec2b)

local deltax = Vec2b.x - Vec2a.x

local deltay = Vec2b.y - Vec2a.y

return math.sqrt(math.pow(deltax, 2) + math.pow(deltay, 2))

end

 

function GetHeadingBetween(Vec2a, Vec2b)

local deltax = Vec2b.x - Vec2a.x

local deltay = Vec2b.y - Vec2a.y

if (deltax > 0) and (deltay == 0) then

return 360

elseif (deltax > 0) and (deltay > 0) then

return math.deg(math.atan(deltay / deltax))

elseif (deltax == 0) and (deltay > 0) then

return 90

elseif (deltax < 0) and (deltay > 0) then

return 90 - math.deg(math.atan(deltax / deltay))

elseif (deltax < 0) and (deltay == 0) then

return 180

elseif (deltax < 0) and (deltay < 0) then

return 180 + math.deg(math.atan(deltay / deltax))

elseif (deltax == 0) and (deltay < 0) then

return 270

elseif (deltax > 0) and (deltay < 0) then

return 270 - math.deg(math.atan(deltax / deltay))

end

end

[Steggles]

This is a hell of a lot cleaner to get a bearing between 2 objects:

 

function getBearing(obj1PosX, obj1PosZ, obj2PosX, obj2PosZ)
    local bearing = math.atan2(obj2PosZ - obj1PosZ, obj2PosX - obj1PosX)
    if bearing < 0 then
         bearing = bearing + 2 * math.pi
    end
    bearing = bearing * 180 / math.pi
    return bearing    -- degrees
end

[Cristofer]

Thanks for the replies. But I can´t get it to work. Remember that I´m a newbie with scripting. When pressing F10 and then activate the script I want a text message to appear with the information (distance and heading to the C130 from me/or Bulls eye). I have tried both Ruskybeavers and Steggles versions.

 

 

Is this correct?:

 

local group = Group.getByName('C130')

local unitPos = nil

local units = group:getUnits()

if units then

unitPos = Unit.getByName(units[1]:getName()):getPosition()

end

 

local group = Group.getByName('Player')

local unitPos = nil

local units = group:getUnits()

if units then

unitPos = Unit.getByName(units[1]:getName()):getPosition()

end

 

local myVec2Position = {x = myVec3Position.p.x, y = myVec3Position.p.z}

 

function GetDistance(Vec2a, Vec2b)

local deltax = Vec2b.x - Vec2a.x

local deltay = Vec2b.y - Vec2a.y

return math.sqrt(math.pow(deltax, 2) + math.pow(deltay, 2))

end

 

function GetHeadingBetween(Vec2a, Vec2b)

local deltax = Vec2b.x - Vec2a.x

local deltay = Vec2b.y - Vec2a.y

if (deltax > 0) and (deltay == 0) then

return 360

elseif (deltax > 0) and (deltay > 0) then

return math.deg(math.atan(deltay / deltax))

elseif (deltax == 0) and (deltay > 0) then

return 90

elseif (deltax < 0) and (deltay > 0) then

return 90 - math.deg(math.atan(deltax / deltay))

elseif (deltax < 0) and (deltay == 0) then

return 180

elseif (deltax < 0) and (deltay < 0) then

return 180 + math.deg(math.atan(deltay / deltax))

elseif (deltax == 0) and (deltay < 0) then

return 270

elseif (deltax > 0) and (deltay < 0) then

return 270 - math.deg(math.atan(deltax / deltay))

end

end

 

 

 

Or the same start but with Steggles code.

[sea2sky]

No, if that would be your final script - it is far from being correct. It seems like you need to get familiar with some basic programming concepts, i.e. how to call functions, how to pass variables etc etc.

[Steggles]

Here you go. Make sure you set the PILOT names for the units in the editor. You will have to format the output too cause it has a heap of decimal places.

 

function getBearing(obj1PosX, obj1PosZ, obj2PosX, obj2PosZ)
   local bearing = math.atan2(obj2PosZ - obj1PosZ, obj2PosX - obj1PosX)
   if bearing < 0 then
       bearing = bearing + 2 * math.pi
   end
   bearing = bearing * 180 / math.pi
   return bearing    -- degrees
end

function getDistance(obj1PosX, obj1PosZ, obj2PosX, obj2PosZ)
   local xDiff = obj1PosX - obj2PosX
   local yDiff = obj1PosZ - obj2PosZ
   return math.sqrt(xDiff * xDiff + yDiff * yDiff) -- meters
end


local unit = Unit.getByName('C130') -- Set Pilot name (not group name) of the C130 in the editor to C130
local unitPos = unit:getPosition()

local player = Unit.getByName('Player') -- Set Pilot name (not group name) of player slot to Player
local playerPos = player:getPosition()

local distance = getDistance(playerPos.p.x, playerPos.p.z, unitPos.p.x, unitPos.p.z)
local bearing = getBearing(playerPos.p.x, playerPos.p.z, unitPos.p.x, unitPos.p.z) --bearing from playerPos to unitPos

trigger.action.outText("BRA: C130 " .. bearing .. " degrees for " .. distance .. " meters.",10)

 

Hint: If you want the units altitude too, its unitPos.p.y and its in meters

Edited November 11, 2016 by Steggles

[Cristofer]

Yeah, it works. Thanks alot.:thumbup:

 

How do I format the output?

[Steggles]

Yeah, it works. Thanks alot.:thumbup:

 

How do I format the output?

 

http://lua-users.org/wiki/StringLibraryTutorial

 

Look at the string.format() function.

 

Something like this:

trigger.action.outText("BRA: C130 " .. string.format("%03d",bearing) .. " degrees for " .. string.format("%8.1f",distance) .. " meters.",10)

 

You can of course apply some maths to change meters to NM or KM etc before displaying as well if you wanted.