Leaderboard

Define your second line. In 3D, you can get infinite number of angles, depending of this second line definition. (This is true for 2D too, but considering Ox axis as reference, there is only one possibility) It seems you know the angle in your code is wrong, so you know what this angle should be. If you cannot describe the problem better, then upload a dwg and explain the desired output.

rough direction, I think 1. start by creating multiple offsets inside the room. ( https://forums.autodesk.com/t5/visual-lisp-autolisp-and-general/continuous-offset-command/m-p/6296766/highlight/true#M340946 ) 2. and it stops when the distance between each vertex of entlast is less than the offset value. Since we are going to unite the lines, this loop must be an even number. If the counting result is an odd number, delete the last loop (entlast) 3. Select the starting edge as user input. Among the vertices of the first selected boundary, the nearest point is selected. Explode the first and second created loops among the created loops and extend them to the boundary room. this is in & out. 4. Twist and connect all loops after the 3rd, based on the corner. connect Inside and outside with 2 pairs. This connection is sufficient because it is only based on vertices close to the selected edge. 5. Connect them all with pedit and fillet all vertices with Lisp like FMP. ( https://forums.autodesk.com/t5/visual-lisp-autolisp-and-general/fillet-multiple-polyline-all-at-once-by-lisp/m-p/6473166/highlight/true#M343470 )

Does that mean that you have one polyline in a drawing ? And what about the related texts ? You need to elaborate your request a bit further.