Calculating faces and vertices

Questions
1

Hi,
I am trying to calculate faces and vertices. I am asking this question to know that I am in the right way.
If mesh.geometry.index.count/3 is the count of triangles in the geometry, is mesh.geometry.attributes.position.count/3 the number of vertices?
If not how do I calculate vertices?
In the mesh I tried, position.count was 828 and index.count was 2196.
I don’t understand how position works with index. I’m a bit confused here. It will be helpful if you can explain that.
Thanks,
Binoy

2

See simple examples from the Collection of examples from discourse.threejs.org

BufferGeometryNonIndexed
BufferGeometryIndexed
and
NumberingHelperExamples

somewhat more sophisticated
MorphBoxSphere
RoundedBoxFlatUV

3

No, the number of vertices is defined by mesh.geometry.attributes.position.count. If you want to read a vertex, do it like so:

const positionAttribute = mesh.geometry.getAttribute( 'position' );

const vertex= new THREE.Vector3();

for ( let i= 0; i< positionAttribute.count; i ++ ) {

	vertex.fromBufferAttribute( positionAttribute, i );

	// do something with the vertex

}
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