make construction line (similiar to autocad function/methode)

if you familiar with autodesk autocad , you must be know about "construction line", but how to make it with librecad?
oke I'll try to explain it with my method.
here we go....
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----make construction line (similiar to autocad function/methode)----

1. go to line >> horizontal / vertical (as you need).
2. choose "middle" as snap point, for length you can fiil it as long as you need , I suggest you to fill it as long as possible.
3. you have a long line which ready to use.

how about free construction line (have a free direction)? I still try to find the way, if you have your own method, please reply this post so we can share our method...
thanks...

I'm not familiar with AutoCAD, but LibreCAD has construction layer feature.
It was called 'Help layer' in past:
https://wiki.librecad.org/index.php?title=HowTos_and_Guides#Help_Layer
And is called 'Construction layer' now:
https://wiki.librecad.org/index.php?title=Layers#Construction_Layers

Draw any line, any direction, length doesn't matter. When construction layer attribute is switched on, all lines become infinite.
There's an icon in layer list to toggle it.

Armin

but, the construction layer is unusable as "line" , it's just guide line...

Construction Lines in LibreCAD are almost the same as those in AutoCAD About Contruction Lines
The main difference seems to be that AutoCAD allows for construction circles based on arcs (something that can be replicated in LibreCAD with a normal circle suitably attributed). Either way both regard such lines as temporary guides to assist in placing other entities. While I have not used AutoCAD for about 30 years the official literature seems to make this fairly clear.

What I find fascinating about LibreCAD is that any existing straight line (excluding those that are either polylines or part of a rectangle) can be turned (temporarily) into a construction line by toggling on construction layer. You can then create a new entity remote from but in line with that existing straight line then turn off the construction layer. This gives almost the best of both worlds which I think is what you were actually hoping to achieve. Draw your straight line (horizontal, vertical or at an arbitrary angle), make it as long as it needs to be as a part of the drawing then switch on construction layer. Add other entities as required including additional straight lines which will also become temporary construction lines. If you need a permanent construction layer (or layers) simply create them and turn visibility on and off. The whole system is extremely flexible.