Merge pull request #7404 from barroij/meshCloneReturnType

restore Mesh.clone return type

src/Meshes/instancedMesh.ts

@@ -390,7 +390,7 @@ export class InstancedMesh extends AbstractMesh {
      *
      * Returns the clone.
      */
-    public clone(name: string, newParent: Nullable<Node>= null, doNotCloneChildren?: boolean): Nullable<AbstractMesh> {
+    public clone(name: string, newParent: Nullable<Node>= null, doNotCloneChildren?: boolean): InstancedMesh {
         var result = this._sourceMesh.createInstance(name);
 
         // Deep copy

src/Meshes/linesMesh.ts

@@ -13,7 +13,6 @@ import { MaterialHelper } from '../Materials/materialHelper';
 
 import "../Shaders/color.fragment";
 import "../Shaders/color.vertex";
-import { AbstractMesh } from './abstractMesh';
 
 /**
  * Line mesh
@@ -224,7 +223,7 @@ export class LinesMesh extends Mesh {
     /**
      * Returns a new LineMesh object cloned from the current one.
      */
-    public clone(name: string, newParent: Nullable<Node> = null, doNotCloneChildren?: boolean): Nullable<AbstractMesh> {
+    public clone(name: string, newParent: Nullable<Node> = null, doNotCloneChildren?: boolean): LinesMesh {
         return new LinesMesh(name, this.getScene(), newParent, this, doNotCloneChildren);
     }
 

src/Meshes/mesh.ts

@@ -2201,7 +2201,7 @@ export class Mesh extends AbstractMesh implements IGetSetVerticesData {
      * @param clonePhysicsImpostor allows/denies the cloning in the same time of the original mesh `body` used by the physics engine, if any (default `true`)
      * @returns a new mesh
      */
-    public clone(name: string = "", newParent: Nullable<Node> = null, doNotCloneChildren?: boolean, clonePhysicsImpostor: boolean = true): Nullable<AbstractMesh> {
+    public clone(name: string = "", newParent: Nullable<Node> = null, doNotCloneChildren?: boolean, clonePhysicsImpostor: boolean = true): Mesh {
         return new Mesh(name, this.getScene(), newParent, this, doNotCloneChildren, clonePhysicsImpostor);
     }
 

src/Meshes/transformNode.ts

@@ -1224,7 +1224,7 @@ export class TransformNode extends Node {
      * @param doNotCloneChildren Do not clone children hierarchy
      * @returns the new transform node
      */
-    public clone(name: string, newParent: Nullable<Node>, doNotCloneChildren?: boolean): Nullable<TransformNode> {
+    public clone(name: string, newParent: Nullable<Node>, doNotCloneChildren?: boolean) : Nullable<TransformNode> {
         var result = SerializationHelper.Clone(() => new TransformNode(name, this.getScene()), this);
 
         result.name = name;