Fix NME PBR default setup (#16806)

https://playground.babylonjs.com/#T7FXR8#78 should render both sides in
a similar way.

Author: sebavan

packages/dev/core/src/Materials/Node/Blocks/PBR/pbrMetallicRoughnessBlock.ts

@@ -786,6 +786,7 @@ export class PBRMetallicRoughnessBlock extends NodeMaterialBlock {
 
         // Advanced
         defines.setValue("BRDF_V_HEIGHT_CORRELATED", true);
+        defines.setValue("LEGACY_SPECULAR_ENERGY_CONSERVATION", true);
         defines.setValue("MS_BRDF_ENERGY_CONSERVATION", this.useEnergyConservation, true);
         defines.setValue("RADIANCEOCCLUSION", this.useRadianceOcclusion, true);
         defines.setValue("HORIZONOCCLUSION", this.useHorizonOcclusion, true);

packages/dev/core/src/Materials/Node/Blocks/PBR/subSurfaceBlock.ts

@@ -180,17 +180,19 @@ export class SubSurfaceBlock extends NodeMaterialBlock {
             ${state._declareLocalVar("vTintColor", NodeMaterialBlockConnectionPointTypes.Vector4)} = vec4${state.fSuffix}(${tintColor}, ${refractionTintAtDistance});
             ${state._declareLocalVar("vSubSurfaceIntensity", NodeMaterialBlockConnectionPointTypes.Vector3)} = vec3(${refractionIntensity}, ${translucencyIntensity}, 0.);
             ${state._declareLocalVar("dispersion", NodeMaterialBlockConnectionPointTypes.Float)} = ${dispersion};
-            #ifdef LEGACY_SPECULAR_ENERGY_CONSERVATION
-                vec3 vSpecularEnvironmentReflectance = vec3(max(colorSpecularEnvironmentReflectance.r, max(colorSpecularEnvironmentReflectance.g, colorSpecularEnvironmentReflectance.b)));
-            #endif
             subSurfaceOut = subSurfaceBlock(
                 vSubSurfaceIntensity
                 , vThicknessParam
                 , vTintColor
                 , normalW
             #ifdef LEGACY_SPECULAR_ENERGY_CONSERVATION
-                , vSpecularEnvironmentReflectance
-            #else
+        `;
+
+        code += isWebGPU
+            ? `, vec3f(max(colorSpecularEnvironmentReflectance.r, max(colorSpecularEnvironmentReflectance.g, colorSpecularEnvironmentReflectance.b)))/n`
+            : `, vec3(max(colorSpecularEnvironmentReflectance.r, max(colorSpecularEnvironmentReflectance.g, colorSpecularEnvironmentReflectance.b)))/n`;
+
+        code += `#else
                 , baseSpecularEnvironmentReflectance
             #endif
             #ifdef SS_THICKNESSANDMASK_TEXTURE