Update sheen export based on latest specifications

dist/preview release/glTF2Interface/babylon.glTF2Interface.d.ts

@@ -1032,9 +1032,9 @@ declare module BABYLON.GLTF2 {
 
     /** @hidden */
     interface IKHR_materials_sheen {
-        sheenColorFactor: number[];
-        sheenTexture: ITextureInfo;
-        sheenRoughnessFactor: number;
+        sheenColorFactor?: number[];
+        sheenTexture?: ITextureInfo;
+        sheenRoughnessFactor?: number;
     }
 
     /**

serializers/src/glTF/2.0/Extensions/KHR_materials_sheen.ts

@@ -6,15 +6,10 @@ import { PBRMaterial } from 'babylonjs/Materials/PBR/pbrMaterial';
 import { Texture } from 'babylonjs/Materials/Textures/texture';
 import { BaseTexture } from 'babylonjs/Materials/Textures/baseTexture';
 import { Nullable } from 'babylonjs/types';
+import { IKHR_materials_sheen } from 'babylonjs-gltf2interface';
 
 const NAME = "KHR_materials_sheen";
 
-interface IKHR_materials_sheen {
-    intensityFactor: number;
-    colorFactor: number[];
-    colorIntensityTexture?: ITextureInfo;
-}
-
 /**
  * @hidden
  */
@@ -90,15 +85,15 @@ export class KHR_materials_sheen implements IGLTFExporterExtensionV2 {
                     node.extensions = {};
                 }
                 const sheenInfo: IKHR_materials_sheen = {
-                    colorFactor: babylonMaterial.sheen.color.asArray(),
-                    intensityFactor: babylonMaterial.sheen.intensity
+                    sheenColorFactor: babylonMaterial.sheen.color.asArray(),
+                    sheenRoughnessFactor: babylonMaterial.sheen.roughness ?? 0
                 };
 
                 if (babylonMaterial.sheen.texture) {
                     let textureIndex = this._getTextureIndex(babylonMaterial.sheen.texture);
 
                     if (textureIndex > -1) {
-                        sheenInfo.colorIntensityTexture = this._textureInfos[textureIndex] ;
+                        sheenInfo.sheenTexture = this._textureInfos[textureIndex] ;
                     }
                 }