# Straight Skeleton

![](https://3521261292-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LPHXQ1FZ8W_xSW4Nb61%2Fuploads%2Fgit-blob-ee9456f985063dd18300a40de6d56829a4522ac7%2FStraight_Skeleton.png?alt=media)

![](https://3521261292-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LPHXQ1FZ8W_xSW4Nb61%2Fuploads%2Fgit-blob-8c7c305c1b274fd2ae506f8a1df8242731ab1fa3%2FStraight_Skeleton.png?alt=media) - [\[source code\]](https://github.com/ladybug-tools/honeybee-grasshopper-core/blob/master/honeybee_grasshopper_core/src/HB%20Straight%20Skeleton.py)

Get the straight skeleton and core/perimeter sub-faces for any planar geometry.

This component uses a modified version of the the polyskel package (<https://github.com/Botffy/polyskel>) by Armin Scipiades (aka. @Bottfy), which is, itself, a Python implementation of the straight skeleton algorithm as described by Felkel and Obdrzalek in their 1998 conference paper Straight skeleton implementation (<https://github.com/Botffy/polyskel/blob/master/doc/StraightSkeletonImplementation.pdf>).

### Inputs

* **floor\_geo \[Required]**

Horizontal Rhino surfaces for which the straight skeleton will be computed.

* **offset**

An optional positive number that will be used to offset the perimeter of the geometry to output core/perimeter polygons. If a value is plugged in here and the straight skeleton is not self-intersecting, perim\_poly and core\_poly will be ouput.

### Outputs

* **report**

Reports, errors, warnings, etc.

* **skeleton**

A list of line segments that represent the straight skeleton of the input \_floor\_geo. This will be output from the component no matter what the input \_floor\_geo is.

* **perim\_poly**

A list of breps representing the perimeter polygons of the input *floor\_geo. This will only be ouput if an offset* is input.

* **core\_poly**

A list of breps representing the core polygons of the input *floor\_geo. This will only be ouput if an offset* is input and the offset is not so great as to eliminate the core.