message: added Loci.getPrincipalAxes
diff: @@ -13,6 +13,7 @@ import { Vec3 } from '../mol-math/linear-algebra';
  import { OrderedSet } from '../mol-data/int';
  import { Structure } from './structure/structure';
  import { capitalize } from '../mol-util/string';
  +import { PrincipalAxes } from '../mol-math/linear-algebra/matrix/principal-axes';
  /** A Loci that includes every loci */
  export const EveryLoci = { kind: 'every-loci' as 'every-loci' }
  @@ -154,6 +155,28 @@ namespace Loci {
  return boundingSphere ? Vec3.copy(center || Vec3.zero(), boundingSphere.center) : undefined
  }
  + export function getPrincipalAxes(loci: Loci): PrincipalAxes | undefined {
  + if (loci.kind === 'every-loci' || loci.kind === 'empty-loci') return void 0;
  +
  + if (loci.kind === 'structure-loci') {
  + return StructureElement.Loci.getPrincipalAxes(Structure.toStructureElementLoci(loci.structure))
  + } else if (loci.kind === 'element-loci') {
  + return StructureElement.Loci.getPrincipalAxes(loci)
  + } else if (loci.kind === 'link-loci') {
  + // TODO
  + return void 0;
  + } else if (loci.kind === 'shape-loci') {
  + // TODO
  + return void 0;
  + } else if (loci.kind === 'group-loci') {
  + // TODO
  + return void 0;
  + } else if (loci.kind === 'data-loci') {
  + // TODO maybe add loci.getPrincipalAxes()???
  + return void 0;
  + }
  + }
  +
  //
  const Granularity = {
  