Dynamically resizing an offset polygon by specifying area

Grasshopper
1

Playing with a Coverage/FAR tool that is constrained on 3 sides and dynamically offsets to meet an area slider. Works fine on a rectangle (top definition) but more complex on the lower when the polygon has different sides. Without using code (only GH components, but can use Expression Editor), any idea how I can make the lower one work like the top one?
Any advice is appreciated!

Code Exercise 4 Sided Polygon.gh (29.3 KB)

Code Exercise 4 Sided Polygon.3dm (1.9 MB)

3

Can you explain the problem again/better?

4

Thanks @maje90 for your reply.

In the definition, there are two definitions, and I want the second definition to work like the first one:

  • The top definition is based on a rectangular parcel/lot that divides an area by the length of a line to determine the offset of the line to achieve that area (using width by depth for the area of a rectangle). This example shows how I would like the second to function similarly
  • The bottom definition is for a non-rectangular 4-sided polygon that I would like to function the same way but cannot find an area formula for that I can use to do the same thing.
5

umm… :thinking:

This definition:

2021-09-13 13_32_12-Grasshopper - area_
2021-09-13 13_32_12-Grasshopper - area_2118×415 97.7 KB

target polygon area.gh (18.0 KB)
given an area factor, calculate the needed offset distance of a planar XY polyline.
There is a small c# script to ensure the polyline is counterclockwise and a cluster that does the main math and outputs the needed offset distance.

The c# script:

 private void RunScript(Curve C, ref object CCWC)
  {
    if(C.ClosedCurveOrientation() == Rhino.Geometry.CurveOrientation.Clockwise) C.Reverse();
    CCWC = C;
  }

The cluster:

2021-09-13 13_29_30-Grasshopper - Edit_ Cluster_
2021-09-13 13_29_30-Grasshopper - Edit_ Cluster_2232×398 106 KB

Works with any point-count polyline.
Works also for >1 factors, meaning the final area will be larger than the original curve’s.
Fails if self-intersections happens in original or final curve…

Barely tested. :sweat_smile: :laughing:

I still am unable to “navigate” your definition, but I hope this cluster will helps you somehow…