Non tri faces to mesh

Questions
1

hi,

I have a model defined by a list of vertices and a list of faces. But the faces aren’t all triangles but can be any flat convex polygons (triangle, square, pentagon, etc). aka they can be tris, quads and n-gons.

// vertices, list of x,y,z
let vertices = [ 
  x1,y1,z1, 
  x2,y2,z2, 
  x3,y3,z3,
  ...
]

// faces, list of list of indices of vertices
let faces = [
  [1,2,3], // a tri
  [2,3,4,5], // a quad
  [6,7,8,9,10], // a penta
  [4,6,8], // a tri
  ...
]

(for instance a box could be defined by 6 quad faces instead of the usual 12 tris).

I’m thinking of using VertexData and converting every non tri to some tris by a simple fan triangulation but I was wondering if something like that already exists in BJS.

And is this the most efficient way to do this (I can sometimes have 300k+ faces) both in term of time to compute and memory/typescript efficiency ?

Additionally how can I render the orignal faces in wireframe (so without seeing the triangulation) ?

thx

2

You could potentially use lines to draw the faces outlines but as as bjs features to triangulate, i do not think we have such things in stock.

Maybe ear ut provide some ?

Else @jerome or @Cedric might have some ideas ?

3

If you can’t use your DCC to triangulate, then I’d add a process to do it once it’s loaded.
Maybe have 2 meshes: one triangulate for filled rendering and 1 with lines for wire display.
Also, you can try to display lines as a post process to check for normal discontinuities. This implies normals are per face and are the same for all face rasterization.

4

no DCC used. everything is generated directly in the browser by a typescript algorithm which produces tris, quads and n-gons.

So I guess so far doing fan triangulation is the only solution.

thx.

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