[XR] Make sure any model will work with the controller loop (#8758)

* Optional entity types array for XR hit-test

* defensively dealing with missing valueMesh (thou unlikely)

src/XR/motionController/webXRAbstractMotionController.ts

@@ -186,7 +186,7 @@ export interface IMotionControllerMeshMap {
     /**
      * The mesh that will be changed when axis value changes
      */
-    valueMesh: AbstractMesh;
+    valueMesh?: AbstractMesh;
 }
 
 /**
@@ -431,13 +431,13 @@ export abstract class WebXRAbstractMotionController implements IDisposable {
     }
 
     // Look through all children recursively. This will return null if no mesh exists with the given name.
-    protected _getChildByName(node: AbstractMesh, name: string): AbstractMesh {
-        return <AbstractMesh>node.getChildren((n) => n.name === name, false)[0];
+    protected _getChildByName(node: AbstractMesh, name: string): AbstractMesh | undefined {
+        return <AbstractMesh | undefined>node.getChildren((n) => n.name === name, false)[0];
     }
 
     // Look through only immediate children. This will return null if no mesh exists with the given name.
-    protected _getImmediateChildByName(node: AbstractMesh, name: string): AbstractMesh {
-        return <AbstractMesh>node.getChildren((n) => n.name == name, true)[0];
+    protected _getImmediateChildByName(node: AbstractMesh, name: string): AbstractMesh | undefined {
+        return <AbstractMesh | undefined>node.getChildren((n) => n.name == name, true)[0];
     }
 
     /**
@@ -447,7 +447,7 @@ export abstract class WebXRAbstractMotionController implements IDisposable {
      * @hidden
      */
     protected _lerpTransform(axisMap: IMotionControllerMeshMap, axisValue: number, fixValueCoordinates?: boolean): void {
-        if (!axisMap.minMesh || !axisMap.maxMesh) {
+        if (!axisMap.minMesh || !axisMap.maxMesh || !axisMap.valueMesh) {
             return;
         }
 

src/XR/motionController/webXRProfiledMotionController.ts

@@ -17,7 +17,7 @@ import { Logger } from "../../Misc/logger";
 export class WebXRProfiledMotionController extends WebXRAbstractMotionController {
     private _buttonMeshMapping: {
         [buttonName: string]: {
-            mainMesh: AbstractMesh;
+            mainMesh?: AbstractMesh;
             states: {
                 [state: string]: IMotionControllerMeshMap;
             };
@@ -89,7 +89,7 @@ export class WebXRProfiledMotionController extends WebXRAbstractMotionController
                         );
                         dot.material = new StandardMaterial(visualResponseKey + "mat", this.scene);
                         (<StandardMaterial>dot.material).diffuseColor = Color3.Red();
-                        dot.parent = this._buttonMeshMapping[type].states[visualResponseKey].valueMesh;
+                        dot.parent = this._buttonMeshMapping[type].states[visualResponseKey].valueMesh || null;
                         dot.isVisible = false;
                         this._touchDots[visualResponseKey] = dot;
                     }
@@ -145,7 +145,10 @@ export class WebXRProfiledMotionController extends WebXRAbstractMotionController
                     this._lerpTransform(meshes.states[visualResponseKey], value, visResponse.componentProperty !== "button");
                 } else {
                     // visibility
-                    meshes.states[visualResponseKey].valueMesh.isVisible = component.touched || component.pressed;
+                    const valueMesh = meshes.states[visualResponseKey].valueMesh;
+                    if (valueMesh) {
+                        valueMesh.isVisible = component.touched || component.pressed;
+                    }
                     if (this._touchDots[visualResponseKey]) {
                         this._touchDots[visualResponseKey].isVisible = component.touched || component.pressed;
                     }