code: function make( v1, v2, v3 ) {
  
  		var face = new THREE.Face3( v1.index, v2.index, v3.index, [ v1.clone(), v2.clone(), v3.clone() ] );
  		face.centroid.add( v1 ).add( v2 ).add( v3 ).divideScalar( 3 );
  		that.faces.push( face );
  
  		var azi = azimuth( face.centroid );
  
  		that.faceVertexUvs[ 0 ].push( [
  			correctUV( v1.uv, v1, azi ),
  			correctUV( v2.uv, v2, azi ),
  			correctUV( v3.uv, v3, azi )
  		] );
  
  	}
docs: Approximate a curved face with recursively sub-divided triangles.