solved Vertices Position on cube

[Xav]

Hi !,

I'm looking at how vertices work so that I can work with and transform my mesh later.
For that I started with a simple box to find the order and give a number on the vertices group.
Can someone explain to me why numbers 3 and 7 are in the same place? 

https://playground.babylonjs.com/#3CZLNK

Thank you ! 

[jerome]

a cube has 6 sides

each side is composed with 2 triangular facets, so 4 vertices.

Side vertices aren't shared with other sides so they can hold different UVs and normals per side.

I total : 4 * 6 = 24 vertices... some are in the same location.

[Xav]

thank you Jerome

I'm ok with you all 24 vertices match with  nbrVertices = cube.getTotalVertices ();

I follow you well on the 6 face with 4 vertices per face.
There are then 6 vertices of each face that have the same coordinates.

What I would like to do is group them ...  like this

[jerome]

What do you mean by "to group them" ? To replace 3 vertices on the same location by only one ?

[Xav]

Create an array with vertices that are the same coordinated in the same index
for example
myCubeVertices = [[all vertices with same coordinates xyz], [all vertices with same coordinates xyz], ...] ?
Does this seem to me easier to visualize and manipulate?

 

[Arte]

27 minutes ago, Xav said:

Create an array with vertices that are the same coordinated in the same index
for example
myCubeVertices = [[all vertices with same coordinates xyz], [all vertices with same coordinates xyz], ...] ?
Does this seem to me easier to visualize and manipulate?

 

Hi @Xav

Group Vertices

https://playground.babylonjs.com/#3CZLNK#1 

[Xav]

Hi Arte

Cool 

I think I must not be good in my code because group returns only 7 differents positions while we should have 8 ?

https://playground.babylonjs.com/#3CZLNK#2

[Xav]

Ok it's good

https://playground.babylonjs.com/#3CZLNK#3

I changed my loop 

for (var i=0 ; i < nbrVertices ; i+=3){

with:

for (var i=0 ; i < nbrVertices ; i++){

[Xav]

Thanks You !

It's cood: 

https://playground.babylonjs.com/#3CZLNK#5 

[Arte]

[Xav]

I continued my research and I also found this post which helps to understand the function:

On the other side I haven't found information to adapt the uv according to the new position of vertices?

var uvs = mesh.getVerticesData(BABYLON.VertexBuffer.UVKind);

mesh.setVerticesData(BABYLON.VertexBuffer.UVKind, uvs);

What is the relationship between a vertex position vector3 and a UV position vector2 ? 

Thanks

[jerome]

some readings :

http://doc.babylonjs.com/resources/facets

http://doc.babylonjs.com/how_to/createbox_per_face_textures_and_colors