Highlight the conic section formed by a double cone and a plane

Questions
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1

Given a plane and a double cone, I need to highlight the conic section made by their intersection.

I’ve tried to use CSG though it does not seem to work.

Playground

2

Hmm, I would expect this PG to work, but it doesn’t. The result includes more geometry than I would expect. Seems like a possible bug.

https://playground.babylonjs.com/#VI1NQB#2

@sebavan @Evgeni_Popov Any thoughts?

4

CSG won’t work with infinitely thin geometry like a plan. Try to use a box with a very thin thickness instead.

2 Likes
5

It makes sense. I need to visualize the conic section given a mathematical plane though.
Do you have a suggestion for creating a box from a mathematical plane?

6

Here you go: https://playground.babylonjs.com/#VI1NQB#3

1 Like
8

I just got https://playground.babylonjs.com/#VI1NQB#4 working.

1 Like
9

Now, how can I only highlight the edge of the mesh (the “ring” around the edge of the ellipse)?

Edit: I’ve gotten https://playground.babylonjs.com/#VI1NQB#5 working, though it isn’t only the “ring” – it is also the edges conecting the verticies.

10

Maybe this will help? Highlighting Meshes | Babylon.js Documentation (babylonjs.com)

11

I’ve tried to use highlight layer but due to the conic being inside two other meshes, the entire mesh surface is highlighted (rather than the edge).

12

A PG showing this would be helpful. Are you saying you want just the outside ring to be highlighted?

13

Yes - much like a highlight layer usually works, I want the outside edge/ring of the conic section to be highlighted.

14

Using the edge renderer:

3 Likes
15

Thanks!

CSG won’t work with infinitely thin geometry like a plan. Try to use a box with a very thin thickness instead.

This was also very helpful.

Hopefully I’ll have my 3D conic sections editor done soon so I can show it off.

1 Like