Create a new mesh with a polygon points list (Triangulation)

[ElemarJR]

Hello,

Is there an way to create a mesh with an polygon points list? Is there some "triangulator" feature available?

Cheers,

[GameMonetize]

Not for now but we are open for suggestions

[JCPalmer]

Sub-classing BABYLON.Mesh & taking some data structure with the points in the constructor is a very clean way to go.  Constructor processes data into positions, normals, & indices. Keeps Mesh itself from getting to big.

[Temechon]

Check this, it might help : http://www.html5gamedevs.com/topic/3396-create-a-shape-with-more-than-4-vertices/?hl=triangulation

 (only works for planes)

[jerome]

I intend to implement (after seeing the whole video tutorial and I'm only at the end of first chapter, arrg ... great job, guys !) some kind of ribbon mesh :

- two arrays A and B of vertices, each being a kind of curve/path points : A1, A2, ... for array A and B1, B2, ... for array B

- then creation of adjacent triangles between these two pathes A1-B1-A2, B1-A2-B2, A2-B2-A3 and so on until the first end reached on one of the arrays

 

BABYLON.mesh.createRibbon(arrayA, arrayB)

 

not sure I'm very clear :-P

I will try in the playground next weeks

 

I think it could be a light usefool tool to create easily many types of surfaces.

 

By the way, why the name "BABYLON" was chosen ?

[JCPalmer]

You can certainly create a Mesh in the playGround.  Write a function:

function createRibbon(mesh, arrayA, arrayB){   var positions = [];   var indices = [];    // process Arrays into positions & indices    ...      var normals = new Array[positions.length];    BABYLON.VertexData.ComputeNormals(positions, indices, normals);    mesh.setVerticesData(BABYLON.VertexBuffer.PositionKind, positions, false);    mesh.setVerticesData(BABYLON.VertexBuffer.NormalKind, normals, false);    mesh.setIndices(indices);}

If you think it needs to become part of the repository though, I think it should be a sub-class, in its own file.  The body of the function the constructor.  Make it possible to exclude for Make your own babylon.

[jerome]

thank you for these nice advices :-)

[ElemarJR]

I would like to implement it. What's the right way to collaborate?

[GameMonetize]

We accept PR on the github repo (please use TypeScript)

 

BABYLON was chosen because I'm a huge fan of Babylon 5 (The TV show )

[ElemarJR]

Perfect! I already forked the repository. What's the policy about using external libraries? I was thinking about implement a Constrained Delaunay triangulation algorithm, to support holes, but there are good implementations available (poly2tri in https://github.com/r3mi/poly2tri.js, for example).

 

Could I use it? should I reimplement everything? Should I think about some plugin system to use it?

[ElemarJR]

I just saw that poly2tri was suggested in the http://www.html5game...l=triangulation (refereced by @temechon)

[Nikos]

 

 

By the way, why the name "BABYLON" was chosen ?

I'm also not to sure about the name, why not call it Athens?

 

btw I'm wanting to create some more primitive meshes , is this of sort of thing we can contribute to the babylon github repo?

[RaananW]

By the way, why the name "BABYLON" was chosen ?

 

Here - http://en.wikipedia.org/wiki/Kosh_Naranek ( Just add Delta :-) )

[Dad72]

I'm also not to sure about the name, why not call it Athens?

 

It's a joke ??? At this stage of development, it's a little late to suggest another name. So why a name is better than another ? And Three.js, why not name it Four.js ? Athens? Why is it better than Babylon?

[Temechon]

I think it was a joke

[jerome]

I'm sure it's a joke

antic cities competition, arf

 

@JCPalmer : thanx again for your help => http://www.html5gamedevs.com/topic/11502-ribbon-mesh-first-attempt/

[GameMonetize]

 

 

What's the policy about using external libraries?

We do not allow external dependencies. But we accept optional dependencies (like for physics)

[ElemarJR]

I did some experiments using Babylon and poly2tri (oss project thtat implements constrained delaunay algorithm).

 

Here is the result:

 

 

I created a little extension to Babylon.

 

https://github.com/ElemarJR/BABYLON.Triangulation/blob/master/src/babylon.triangulation.ts

 

What do you think? Should I try to put it into BABYLONJS? 

[GameMonetize]

Definitely!

 

IPoint2 could be replaced by BABYLON.Vector2

[ElemarJR]

Hello,

 

The implementation of triangulation with constrained delaunay (support to holes it's not trivial). poly2tri implements the algorithm in a good way and I don't think so that reimplement it is a good idea.

 

 

 

 

To create the mesh of the screenshots I wrote, using my current implementation, something like that:

var rectangle = BABYLON.Polygon.rectangle(-15, -15, 15, 15);var ground = new BABYLON.PolygonMeshBuilder("ground", rectangle, this.scene)    .addHole(BABYLON.Polygon.bird())    .build();

Do you really think that create a "PolygonMesh" class could be simpler to use? I think that is best to verify the reference to poly2tri in the build method.

[ElemarJR]

I will create a PR to discuss it in github

[GameMonetize]

Excellent. I will integrate it with babylon.js (grunt, etc..)

 

In the meantime do you think you can also integrate an extrusion option?

[GameMonetize]

Do you think you can create a wiki page like this one for your feature?

https://github.com/BabylonJS/Babylon.js/wiki/Using-the-debug-layer

[GameMonetize]

I will check-in some little fixes but here is your work integrated well done!

http://www.babylonjs-playground.com/#10IOII#1

[ElemarJR]

wow! that's huge! I'm really happy now. Yes, I will try to write an wiki (I am not sure if my english is good enough to do that, but...) page and to provide extrusion.