I currently have a set of vectors and would like to perform triangulation.
I know there’s earcut but it only performs on 2D.
My question is the following:
if I have a custom shape or a set of vectors how can I get all the triangles coordinates (I guess it’s also named faces) of this shape.
Thanks in advance
That is a very general formulation. How specifically is the shape described? Where do the vectors come from? Are they points on a surface?
I have carried out special triangulations.
Addon for triangulation of implicit surfaces/ forms with holes
Triangulation sphere with holes
Triangulation cylinder with holes
Inner Geometry (Triangulation)
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@hofk First thank you for your answer.
The points represents a set of speakers positionned in space onto a convex hull (Sphere). I need to get speakers by triplets ( faces )
According the documentation there is a third parameter dim that represents the dimension of the vertices. For 3D vertices you should be using dim=3. Have you tried whether 3D earcut works fine?
BTW, I’m not sure you actually need triangulation (i.e. I’m still struggling to understand what you actually want to do).
@PavelBoytchev thanks for your answer
the documentation of earcut says
Note that Earcut is a 2D triangulation algorithm, and handles 3D data as if it was projected onto the XY plane (with Z component ignored).
I’m implementing the VBAP alogrihtm where a certain number of speakers are positionned onto a convex hull.The sound is then played on a set of three speakers (triplet).The triangulation algorithm would help me get the sets of speakers 3 by 3.Any ideas?
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The link to the paper is not accessible to me. I do not understand “get the sets of speakers 3 by 3”. Somehow there must be some rule how to select 3x3 speakers out of all speakers. I have absolutely no idea what this rule might be. If you can formalize the rule of selection, then you might be able to translate it into code.
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If I’m right, it’s this topic - isn’t it? Working with Sphere 
@hofk exactly
@PavelBoytchev if you have let’s say 4 speakers ( 4 points ) Then you have 2 sets of 3 speakers. just a simple triangulation but in 3D
Still struggling. Am I close with this:
- you have a cloud of points in 3D space
- the points are on (or approximately on) the surface of an imaginary sphere
- you want to make a mesh of triangles using these points as vertices.
If this is the case, I’d suggest to try the ConvexGeometry. If all points are on a sphere, then there are no internal points and all points will all take part in the convex hull … which is made of triangles.
@PavelBoytchev so yes all the points are onto the convex hull but my question is how can I get all the coordinates of one mesh of the geometry?thanks
Generally the coordinates of all vertices of a mesh are stored in the position attribute of its geometry. You can get this data and retrieve the XYZ of each vertex.
@PavelBoytchev I know that but I need the vertices of one mesh by one mesh.I don’t need only the vertices.
I’m sorry. My confusion increases exponentially. I do not understand this “one mesh by one mesh”. I do not understand how knowing vertex position will help you with triangulation. I do not understand how 4 speakers will make 2 sets of three speakers (as I can see 4 sets of 3 speakers each – the number of faces of tetrahedron). As I’m not native English speaker, it is most likely my fault for this misunderstanding. Again, I’m sorry. I hope someone could provide adequate help.
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@PavelBoytchev I’ll try one last time
I need the coordinates of each triangles vertices ( first triangle [[ x, y, z ],[x,y,z],[x,y,z]] then second triangle [[ x, y, z ],[x,y,z],[x,y,z]]) THanks in advance, if you don’t understand I won’t bother.
@hofk I’ve looked a bit sounds great but how can I install it I don’t see any npm packages (I guess I need to import the script in my project). Isn’t there a more lightweight solution, I will use that in a commercial app so I hope the licence is MIT? Thanks
This demo defines randomly N positions on a sphere (the speakers), then builds a triangular mesh from their positions and finally shows one by one the triangles (marking their vertices with red spheres).
https://codepen.io/boytchev/full/emOjwOB
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@PavelBoytchev I guess this is exactly what I need. I’ll dive into the code and once understood I’ll mark that as a solution.You have done this just for me or is this an already made script?If you have done this just for me I really appreciate that.Thank you a lot
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I did it just now to show what I mean by using ConvexGeometry and its position attribute.
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There are different variants:
See the examples e.g.
THREEi.js/examples/InnerGeometryTHREEi_01.html at 6864a2786ca533edb59fb0bccf1df6bab1b664b9 · hofk/THREEi.js · GitHub
THREEi.js/examples/sphereWithHolesTHREEi.html at 6864a2786ca533edb59fb0bccf1df6bab1b664b9 · hofk/THREEi.js · GitHub
< script src=“…/js/THREEi.js”>< /script>
or as function see e.g. TriangulationSphereWithHoles
"THREEi
three.js addon for triangulation of implicit surfaces and for forms with holes. The addon generates indexed BufferGeometries.
License identical to three.js "
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