Surfaces

I am not a skilled user of LibreCAD, and need to make surfices with lines and arks. May I have some advice

Hi,
I'm not a skilled user too . For the surface of a quadrilateral (a slightly twisted room) ABCD, I use these formulas :
 
2S = abs((xA-xC)*(yB-yD)) + abs((xB-xD)*(yA-yC)) Where xM,yM are the coordinate off M point...

I need  to copy manually each coordinate > Excel :( Is there a function for this ?

Or 2S = D * (H1 + H2) Where D is the diagonal BD and Hx the heights on D of A and C
I need to create 3 new lines and  > Excel ...

http://villemin.gerard.free.fr/GeomLAV/Carre/QuadAire.htm



If a programmer can look into :)

Sorry for my poor English


 

I am not sure what you mean with "make surfices".
 If you want to calculate an area, you can fill the boundaries with a hatch. When the hatch is created, the hatched area is indicated in the command line. It also works with arks. The boundaries have to be a closed shape.
 But unfortunately there is no way to ask the area of an existing shape.
There is Info - Polygonal Area, but this doesn't work with arks.

dellus wrote

But unfortunately there is no way to ask the area of an existing shape.

Seems it would be trivial to change the existing Polygonal Area tool from requiring user to click each point of a polygon to use the existing nodes of a selected polygon.

iirc Complexities include donut polygons and polygons occurring as multiple objects.