How to draw a simple line "as if done with the pencil over a 3D drawing in real life"?

I am developing an architecture application with webgl where i render some 3D shapes and i need to display the dimensions.

To express myself better i ask you to refer to this screenshot (found on google):



Somehow in unity i already did the "3d shape work" and now i need to "draw" over it the lines with the dimensions.
I do not want to use small arrows (like in the picture above) but just simple lines and writing numbers close to them.
When i zoom (=when i move the camera) i do not want that the lines become bigger.

I tried with tiny cilynders but on zooming the cilynders stop to be lines and become "bold objcets".

I think i am missing some basic technique here. I hope you can suggest a way to perform this task. Thanks.

 

For lines, could try:
https://docs.unity3d.com/ScriptReference/GL.LINES.html
But it wont have those line arrows, you'd have to draw them also yourself..

This might work better,
http://forum.unity3d.com/threads/vectrosity-fast-and-easy-line-drawing.49941/

For numbers, maybe this
https://docs.unity3d.com/Manual/class-TextMesh.html
Or
https://github.com/aras-p/UnityStbEasyFont

 

Thanks, Vectrosity seems to do what I need, I do not understand why a so basic thing is not part of Unity itself, but the price is not high at all.

About numbers i am ok with unity 3d text.

Thanks.

 

Because it's not a required/needed tool used by very many developers to create games, unlike the sprite packer or mecanim, or animator, particle systems etc etc.