Duplicate vertices in buffergeometry

[hofk]

Possibly the example contributes to the understanding of the matter.

From the Collection of examples from discourse.threejs.org

Curved2Geometry

The vertices and normals can be determined in various ways to achieve appropriate effects. See the source code of the example.

function generateCap( top ) { ... }

---

if ( wTop && !flatTop ) { // calculate new normals at top seam
	
	for( let j = 0; j <= g.radial; j ++ ) {
		
		smoothEdge( ( g.radial + 1 ) * ( g.vertical + 1 ) + 1 + j, j );
		
	}
	
}

---

function smoothEdge( idxa, idxb ) {
	
	let v3a = new THREE.Vector3( );
	let v3b = new THREE.Vector3( );
	
	v3a.set( g.attributes.normal.getX( idxa ), g.attributes.normal.getY( idxa ), g.attributes.normal.getZ( idxa ) );
	v3b.set( g.attributes.normal.getX( idxb ), g.attributes.normal.getY( idxb ), g.attributes.normal.getZ( idxb ) );
	
	v3.addVectors( v3a, v3b ).normalize( );
	
	g.attributes.normal.setXYZ( idxa, v3.x, v3.y, v3.z );
	g.attributes.normal.setXYZ( idxb, v3.x, v3.y, v3.z );
	
}