How to do a random "scene.pick" on a mesh

[elkyu]

Hi !

 

I have a plane with several faces.

 

I want to do a random scene pick on my mesh. With the picking info I want to get the faceId (pickingInfo.faceId).

 

I tried with scene.pick() with random x and y parameter but it's not working. It always returns me the same face of my plane.

 

How to generate a random scene pick ? (without mouse click)

I think it's very simple but .. my method does'nt work 

 

 

Thanks

[iiceman]

Well... why? Why not use Math.random to get a random face id?

[elkyu]

because I divide my plane in 4 part and I want to pick a face in a part. And the faceId are placed completely randomly in the plane.



Oh, the x and y coordinate are the screen coordinate .. that's why I find always the same face .. (coordinate of my plane its between -1 and 1 ...)

There is a way to do the pick with the plane coordinate ?

I can get a random face id with Math.random, get the 3 vertices of this face and check if it is in the correct part of the plane and try again if not.

But it's very .. painful

I think there is a better way to do that

[jahow]

If you want to pick a face, and not a point in a face, you can do as iiceman suggested:

var indices = mesh.getIndices();var face_count = indices.length/3;var selected_face = Math.floor(Math.random() * face_count);

[elkyu]

 

If you want to pick a face, and not a point in a face, you can do as iiceman suggested:

var indices = mesh.getIndices();var face_count = indices.length/3;var selected_face = Math.floor(Math.random() * face_count);

Read my last post (We posted at the same time, I think ) , So, I can't really do that

[adam]

Do a playground.  Someone might be able to easily see what you are doing wrong.

[iiceman]

Well, I am still not convinced that this approach is the best way, but here is how you do basic ray picking (from a position in a certain direction): http://www.babylonjs-playground.com/#1WI0CZ