how do you read a single line from a text file

I'm making a 3d engine and I want to read an obj file as text (but that's a seperate problem) the problem i'm having is trying to distinguish the lines. as you may know if you've worked with 3d engines before, a line of obj defining a vertecie looks like:

v 0.0625 0.125 0.1875
v 0.0625 0.125 -0.1875
or something like that.

the code I want to use looks something like:

for i in obj.textline //don't know what is.
if i[0] = "v" then
local yes = 2
local verteciex = ""
local verteciey = ""
local verteciez = ""
while i[yes] != " " //space
verteciex = verteciex + i[yes]
yes += 1
end
yes += 1
while i[yes] != " " //space
verteciey = verteciey + i[yes]
yes += 1
end
yes += 1
while i[yes] != " " //space
verteciez = verteciez + i[yes]
yes += 1
end
vertecies.push([verteciex, vertecie2, vertecie3]) //should push [[0.0625, 0.125, 0.1875], [0.0625, -0.125, 0.1875]]
end
end
so does anyone know how to find: the individual line of a text document?

you could use:

lines = text.split("\n")

to turn your text into a list of lines

ok thnks

You can format source code you show here by surrounding it with tripple ``` in first and last line.
Regarding your question ... as Gilles already said :)

Comments to your code:
if i[0] = "v" then should be if i[0] == "v" then , you need to use double == to check for equality.
Also: vertecies.push([verteciex, vertecie2, vertecie3]) , I suspect this should be vertecies.push([verteciex, verteciey, verteciez])

Anyway, I found it interesting, so here is a little example. I saved cube.obj as cube.txt into the asset folder.
The source:

init = function()
  asset_manager.loadText("cube",
    function(data) 
      myText     = data                  // here we receive the text file
      myArray    = myText.split("\n")    // and split it into multiple lines (using the newline special character)
      myVertices = readVertices(myArray) // a sub routine that looks for lines that start with 'v'

      // just for testing, remove the print loop... if not needed
      for i in myVertices print(i) end
    end)  
end

update = function()
end

draw = function()
end

// helper functions

readVertices = function(array)
  local dataList = []
  for i in array
    local data = i.split("  ") // split the line at double SPACE
    if data[0]=="v" then
      verticeX = data[1]*1     // ..*1 converts a string to a number
      verticeY = data[2]*1     // remove it if you want it as string
      verticeZ = data[3]*1
      dataList.push([verticeX,verticeY,verticeZ])
    end
  end
  return dataList
end

The link:
https://microstudio.io/i/TinkerSmith/exampleparsetext/

Hope this helps :) Live Long and Tinker

P.S. ... you know that you can use the Babylon 3D extension in microStudio?