code: function prepare( vector ) {
  
  		var vertex = vector.normalize().clone();
  		vertex.index = that.vertices.push( vertex ) - 1;
  
  		// Texture coords are equivalent to map coords, calculate angle and convert to fraction of a circle.
  
  		var u = azimuth( vector ) / 2 / Math.PI + 0.5;
  		var v = inclination( vector ) / Math.PI + 0.5;
  		vertex.uv = new THREE.UV( u, 1 - v );
  
  		return vertex;
  
  	}
docs: Project vector onto sphere's surface