Mesh perimeters

Questions
1

Hi
I have a mesh loaded and now need to generate another mesh parallel to the surface of my original mesh
Can someone please point me in the right direction on how to get the perimeter of my mesh (at a given height)

I also need to be able to tell if the perimeter is the internal / external one as my original mesh can be hollow

thanks

2

I am not sure to understand exactly the need and what would happen with let s say a sphere ?

3

Ok
so we have a 1m diameter sphere at {0, 0.5, 0}
At y = 0.5 a horizontal plane slicing through the sphere would give me an object (in this instance it is a 1m diameter circle)
I want to get the perimeter of this object so that I can create something parallel to it x metres distant

Hope this makes sense & thanks for taking time to help

4

This is the part that confuses me. what do you mean by parallel to a perimeter ?

Could you draw a picture, maybe this would help ?

Sorry again… my brain is on slomo those days :slight_smile:

5

Hopefully this well help
Continuing with sphere as an example

image
image772×423 71.6 KB

red line is the perimeter of the sphere at y = 0.5m
green line is parallel to red line but 0.25m distant from it

Sphere makes it look easy - but imagine a non-regular object as the starting point

Also object is likely to be hollow so I need to be able to distinguish between internal/external perimeter

Hope this clarifies my problem
Thanks for any help you can offer

6

this is definitely not something simple and some libraries are doing only this :slight_smile:

Basically you need a triangulation library and probably more for the instersection detection.

I d suggest to have a look at earcut for instance to see if they support such use cases.

7

You might want to take a look into convex hull algorithms? Convex hull algorithms - Wikipedia