Identifying Different surfaces in a 3D asset

Questions
1

I am trying to figure out how can i identify surfaces in a 3d object. for example if i have a cube in the scene then i want to be able to mark the faces of the cube with some numbers or tags. I am new to this framework so i was hoping to find some lead/links to solve this problem.

2

Hello and welcome!

For a cube you may use this way (only available when creating a mesh using the MeshBuilder method) - Map Materials to Individual Mesh Faces | Babylon.js Documentation
Here is another link from docs with very simple example - Getting Started - Chapter 2 - Face Materials | Babylon.js Documentation

1 Like
3

Thanks for the help @labris . This helped to get started. Although I would like to do something more general. Like I should be able to import a glb asset (not necessarily a cube) and then find the faces of that object. Right now, I am only interested with identifying flat surfaces and later maybe do something similar to curved surfaces as well.

4

Hope this helps.

5

For GLB assets see Facet Data | Babylon.js Documentation

6

I was assuming he would be importing meshes from another program and wanted some info on how to access the faces if his imported mesh …

7

Yes that’s exactly what I’m trying to do

Here is I what I managed to do following different discussions till now. I can now detect the faces of cube. But if I try the flat surface like a top of cylinder, it behaves differently, possibly because of the circle, so now the problem I’m facing is how to identify flat “curved” surface. I’m thinking I need to use the face normals somehow to achieve this.

8

yup basically the normals needs to be as close as possible so the face is as flat as possible. dot product close to one for normalized normals.

9

I did this for a dice roller that can, in theory, handle any dice model. Detecting flat mesh faces - #25 by ericwood73. PG link is https://playground.babylonjs.com/#P5F4RL#28. It may not work exactly for your use case as I was able to make assumptions about the nature of the faces (the only faces that are not on a flat side would be on the edges or pips/numbers/etc…), but you may get some ideas from it.

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