# Fillet tangent to 3 surfaces (tritangent fillet) command

**URL:** <https://discourse.mcneel.com/t/fillet-tangent-to-3-surfaces-tritangent-fillet-command/151442>\
**Category:** Serengeti (Rhino BETA)\
**Tags:** windows\
**Created:** [December 1, 2022, 10:09am UTC](https://discourse.mcneel.com/t/fillet-tangent-to-3-surfaces-tritangent-fillet-command/151442 "2022-12-01T10:09:22Z")\
**Posts on this page:** 1\
**Showing post:** 10

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**Author:** ![Tom\_P](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/tom_p/32/766520_2.png) [@Tom\_P](https://discourse.mcneel.com/u/Tom_P)\
**Post date:** [December 2, 2022, 12:00am UTC](https://discourse.mcneel.com/t/fillet-tangent-to-3-surfaces-tritangent-fillet-command/151442/10 "2022-12-02T00:00:56Z")

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> [@davidcockey](#):
>
> the orientation of the fillet sections.

those sections should be part of sphere that roles along those three surfaces.  
So each section is an arc.  
the shortest distance of the arc’s center to the 3 surfaces is start, tangent, end on the 3 surfaces.  
or in other, rhino words:  
if you pull the center (violet) of the arc back to the 3 surfaces you should get start, endpoint of arc, and intersection of arc and surface. (blue)  
if the pulled center does not hit the arc (cyan/green points) the section is wrong.

 ![tritangent](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/3/5/2/3523b8128a41d8a8e0acfbac6fafc1985cd63fcb.jpeg)

fare from a robust algorithm … some a simple result full-filling above rule

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/5/0/f/50fbd0463f79fa1158c568d45cbbed9e8abce78a.jpeg)

I see a huge potential in some nice new (nurbs) surface Functions.  
(@pascal - my chrismas-wish 😉 as [patch](https://discourse.mcneel.com/t/xmas-wish-improve-patch/151187) did not make it)  
TritangentSurface  
Sphere tangent to 4 Surfaces  
Fillet with given first rail ( @jordi.rovira “something similar, but with an additional thing”)

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