Add OpenPBR's base_weight material parameter

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

@@ -974,10 +974,11 @@ export class PBRMetallicRoughnessBlock extends NodeMaterialBlock {
                 ,vec4${state.fSuffix}(1.)
                 ,vec2${state.fSuffix}(1., 1.)
             #endif
+                ,1. // Base Weight
             #ifdef OPACITY
                 ,vec4${state.fSuffix}(${opacity})
                 ,vec2${state.fSuffix}(1., 1.)
-            #endif                
+            #endif
             );
 
             ${state._declareLocalVar("surfaceAlbedo", NodeMaterialBlockConnectionPointTypes.Vector3)} = albedoOpacityOut.surfaceAlbedo;

packages/dev/core/src/Materials/PBR/pbrBaseMaterial.ts

@@ -100,6 +100,9 @@ export class PBRMaterialDefines extends MaterialDefines implements IImageProcess
     public ALBEDODIRECTUV = 0;
     public VERTEXCOLOR = false;
 
+    public BASEWEIGHT = false;
+    public BASEWEIGHTDIRECTUV = 0;
+
     public BAKED_VERTEX_ANIMATION_TEXTURE = false;
 
     public AMBIENT = false;
@@ -417,6 +420,12 @@ export abstract class PBRBaseMaterial extends PushMaterial {
      */
     public _albedoTexture: Nullable<BaseTexture> = null;
 
+    /**
+     * OpenPBR Base Weight (multiplier to the diffuse and metal lobes).
+     * @internal
+     */
+    public _baseWeightTexture: Nullable<BaseTexture> = null;
+
     /**
      * AKA Occlusion Texture in other nomenclature.
      * @internal
@@ -559,6 +568,12 @@ export abstract class PBRBaseMaterial extends PushMaterial {
      */
     public _albedoColor = new Color3(1, 1, 1);
 
+    /**
+     * OpenPBR Base Weight (multiplier to the diffuse and metal lobes).
+     * @internal
+     */
+    public _baseWeight = 1;
+
     /**
      * AKA Specular Color in other nomenclature.
      * @internal
@@ -1111,6 +1126,12 @@ export abstract class PBRBaseMaterial extends PushMaterial {
                     }
                 }
 
+                if (this._baseWeightTexture && MaterialFlags.BaseWeightTextureEnabled) {
+                    if (!this._baseWeightTexture.isReadyOrNotBlocking()) {
+                        return false;
+                    }
+                }
+
                 if (this._ambientTexture && MaterialFlags.AmbientTextureEnabled) {
                     if (!this._ambientTexture.isReadyOrNotBlocking()) {
                         return false;
@@ -1413,6 +1434,7 @@ export abstract class PBRBaseMaterial extends PushMaterial {
             "vLightsType",
             "vAmbientColor",
             "vAlbedoColor",
+            "baseWeight",
             "vReflectivityColor",
             "vMetallicReflectanceFactors",
             "vEmissiveColor",
@@ -1422,6 +1444,7 @@ export abstract class PBRBaseMaterial extends PushMaterial {
             "vFogColor",
             "pointSize",
             "vAlbedoInfos",
+            "vBaseWeightInfos",
             "vAmbientInfos",
             "vOpacityInfos",
             "vReflectionInfos",
@@ -1437,6 +1460,7 @@ export abstract class PBRBaseMaterial extends PushMaterial {
             "vLightmapInfos",
             "mBones",
             "albedoMatrix",
+            "baseWeightMatrix",
             "ambientMatrix",
             "opacityMatrix",
             "reflectionMatrix",
@@ -1478,6 +1502,7 @@ export abstract class PBRBaseMaterial extends PushMaterial {
 
         const samplers = [
             "albedoSampler",
+            "baseWeightSampler",
             "reflectivitySampler",
             "ambientSampler",
             "emissiveSampler",
@@ -1612,6 +1637,7 @@ export abstract class PBRBaseMaterial extends PushMaterial {
             }
             if (scene.texturesEnabled) {
                 defines.ALBEDODIRECTUV = 0;
+                defines.BASEWEIGHTDIRECTUV = 0;
                 defines.AMBIENTDIRECTUV = 0;
                 defines.OPACITYDIRECTUV = 0;
                 defines.EMISSIVEDIRECTUV = 0;
@@ -1633,6 +1659,12 @@ export abstract class PBRBaseMaterial extends PushMaterial {
                     defines.ALBEDO = false;
                 }
 
+                if (this._baseWeightTexture && MaterialFlags.BaseWeightTextureEnabled) {
+                    PrepareDefinesForMergedUV(this._baseWeightTexture, defines, "BASEWEIGHT");
+                } else {
+                    defines.BASEWEIGHT = false;
+                }
+
                 if (this._ambientTexture && MaterialFlags.AmbientTextureEnabled) {
                     PrepareDefinesForMergedUV(this._ambientTexture, defines, "AMBIENT");
                     defines.AMBIENTINGRAYSCALE = this._useAmbientInGrayScale;
@@ -1981,6 +2013,7 @@ export abstract class PBRBaseMaterial extends PushMaterial {
         // Order is important !
         const ubo = this._uniformBuffer;
         ubo.addUniform("vAlbedoInfos", 2);
+        ubo.addUniform("vBaseWeightInfos", 2);
         ubo.addUniform("vAmbientInfos", 4);
         ubo.addUniform("vOpacityInfos", 2);
         ubo.addUniform("vEmissiveInfos", 2);
@@ -1993,6 +2026,7 @@ export abstract class PBRBaseMaterial extends PushMaterial {
         ubo.addUniform("vReflectionSize", 3);
         ubo.addUniform("vBumpInfos", 3);
         ubo.addUniform("albedoMatrix", 16);
+        ubo.addUniform("baseWeightMatrix", 16);
         ubo.addUniform("ambientMatrix", 16);
         ubo.addUniform("opacityMatrix", 16);
         ubo.addUniform("emissiveMatrix", 16);
@@ -2005,6 +2039,7 @@ export abstract class PBRBaseMaterial extends PushMaterial {
 
         ubo.addUniform("vReflectionColor", 3);
         ubo.addUniform("vAlbedoColor", 4);
+        ubo.addUniform("baseWeight", 1);
         ubo.addUniform("vLightingIntensity", 4);
 
         ubo.addUniform("vReflectionMicrosurfaceInfos", 3);
@@ -2107,6 +2142,11 @@ export abstract class PBRBaseMaterial extends PushMaterial {
                         BindTextureMatrix(this._albedoTexture, ubo, "albedo");
                     }
 
+                    if (this._baseWeightTexture && MaterialFlags.BaseWeightTextureEnabled) {
+                        ubo.updateFloat2("vBaseWeightInfos", this._baseWeightTexture.coordinatesIndex, this._baseWeightTexture.level);
+                        BindTextureMatrix(this._baseWeightTexture, ubo, "baseWeight");
+                    }
+
                     if (this._ambientTexture && MaterialFlags.AmbientTextureEnabled) {
                         ubo.updateFloat4(
                             "vAmbientInfos",
@@ -2268,6 +2308,8 @@ export abstract class PBRBaseMaterial extends PushMaterial {
                     ubo.updateColor4("vAlbedoColor", this._albedoColor, this.alpha);
                 }
 
+                ubo.updateFloat("baseWeight", this._baseWeight);
+
                 // Misc
                 this._lightingInfos.x = this._directIntensity;
                 this._lightingInfos.y = this._emissiveIntensity;
@@ -2290,6 +2332,10 @@ export abstract class PBRBaseMaterial extends PushMaterial {
                     ubo.setTexture("albedoSampler", this._albedoTexture);
                 }
 
+                if (this._baseWeightTexture && MaterialFlags.BaseWeightTextureEnabled) {
+                    ubo.setTexture("baseWeightSampler", this._baseWeightTexture);
+                }
+
                 if (this._ambientTexture && MaterialFlags.AmbientTextureEnabled) {
                     ubo.setTexture("ambientSampler", this._ambientTexture);
                 }
@@ -2424,6 +2470,10 @@ export abstract class PBRBaseMaterial extends PushMaterial {
             results.push(this._albedoTexture);
         }
 
+        if (this._baseWeightTexture && this._baseWeightTexture.animations && this._baseWeightTexture.animations.length > 0) {
+            results.push(this._baseWeightTexture);
+        }
+
         if (this._ambientTexture && this._ambientTexture.animations && this._ambientTexture.animations.length > 0) {
             results.push(this._ambientTexture);
         }
@@ -2492,6 +2542,10 @@ export abstract class PBRBaseMaterial extends PushMaterial {
             activeTextures.push(this._albedoTexture);
         }
 
+        if (this._baseWeightTexture) {
+            activeTextures.push(this._baseWeightTexture);
+        }
+
         if (this._ambientTexture) {
             activeTextures.push(this._ambientTexture);
         }
@@ -2553,6 +2607,10 @@ export abstract class PBRBaseMaterial extends PushMaterial {
             return true;
         }
 
+        if (this._baseWeightTexture === texture) {
+            return true;
+        }
+
         if (this._ambientTexture === texture) {
             return true;
         }
@@ -2632,6 +2690,7 @@ export abstract class PBRBaseMaterial extends PushMaterial {
             }
 
             this._albedoTexture?.dispose();
+            this._baseWeightTexture?.dispose();
             this._ambientTexture?.dispose();
             this._opacityTexture?.dispose();
             this._reflectionTexture?.dispose();

packages/dev/core/src/Materials/PBR/pbrMaterial.ts

@@ -92,6 +92,13 @@ export class PBRMaterial extends PBRBaseMaterial {
     @expandToProperty("_markAllSubMeshesAsTexturesDirty")
     public albedoTexture: Nullable<BaseTexture>;
 
+    /**
+     * OpenPBR Base Weight (multiplier to the diffuse and metal lobes).
+     */
+    @serializeAsTexture()
+    @expandToProperty("_markAllSubMeshesAsTexturesDirty")
+    public baseWeightTexture: Nullable<BaseTexture>;
+
     /**
      * AKA Occlusion Texture in other nomenclature.
      */
@@ -270,6 +277,13 @@ export class PBRMaterial extends PBRBaseMaterial {
     @expandToProperty("_markAllSubMeshesAsTexturesDirty")
     public albedoColor = new Color3(1, 1, 1);
 
+    /**
+     * OpenPBR Base Weight (multiplier to the diffuse and metal lobes).
+     */
+    @serialize("baseWeight")
+    @expandToProperty("_markAllSubMeshesAsTexturesDirty")
+    public baseWeight = 1;
+
     /**
      * AKA Specular Color in other nomenclature.
      */

packages/dev/core/src/Materials/materialFlags.ts

@@ -22,6 +22,22 @@ export class MaterialFlags {
         AbstractEngine.MarkAllMaterialsAsDirty(Constants.MATERIAL_TextureDirtyFlag);
     }
 
+    private static _BaseWeightTextureEnabled = true;
+    /**
+     * Is the OpenPBR Base Weight texture enabled in the application.
+     */
+    public static get BaseWeightTextureEnabled(): boolean {
+        return this._BaseWeightTextureEnabled;
+    }
+    public static set BaseWeightTextureEnabled(value: boolean) {
+        if (this._BaseWeightTextureEnabled === value) {
+            return;
+        }
+
+        this._BaseWeightTextureEnabled = value;
+        AbstractEngine.MarkAllMaterialsAsDirty(Constants.MATERIAL_TextureDirtyFlag);
+    }
+
     private static _DetailTextureEnabled = true;
     /**
      * Are detail textures enabled in the application.

packages/dev/core/src/Shaders/ShadersInclude/pbrBlockAlbedoOpacity.fx

@@ -10,6 +10,11 @@ albedoOpacityOutParams albedoOpacityBlock(
 #ifdef ALBEDO
     ,in vec4 albedoTexture
     ,in vec2 albedoInfos
+#endif
+    , in float baseWeight
+#ifdef BASEWEIGHT
+    , in vec4 baseWeightTexture
+    , in vec2 vBaseWeightInfos
 #endif
 #ifdef OPACITY
     ,in vec4 opacityMap
@@ -22,7 +27,7 @@ albedoOpacityOutParams albedoOpacityBlock(
 #ifdef DECAL
     ,in vec4 decalColor
     ,in vec4 vDecalInfos
-#endif 
+#endif
 )
 {
     albedoOpacityOutParams outParams;
@@ -63,6 +68,17 @@ albedoOpacityOutParams albedoOpacityBlock(
 
     #define CUSTOM_FRAGMENT_UPDATE_ALBEDO
 
+    // According to OpenPBR:
+    // - for metals, base_weight is a factor to the base_color (F0, thus surfaceAlbedo in
+    //   Babylons.js).
+    // - for dielectrics, base_weight is a factor to the diffuse BRDF (i.e. it should be
+    //   applied in computeDiffuseLighting), but with the diffuse model *currently* used
+    //   in Babylon.js, factoring it into the surfaceAlbedo is equivalent.
+    surfaceAlbedo *= baseWeight;
+    #if BASEWEIGHT
+        surfaceAlbedo *= baseWeightTexture.r;
+    #endif
+
     // _____________________________ Alpha Information _______________________________
     #ifdef OPACITY
         #ifdef OPACITYRGB
@@ -79,7 +95,7 @@ albedoOpacityOutParams albedoOpacityBlock(
     #endif
 
     #if !defined(SS_LINKREFRACTIONTOTRANSPARENCY) && !defined(ALPHAFRESNEL)
-        #ifdef ALPHATEST 
+        #ifdef ALPHATEST
             #if DEBUGMODE != 88
                 if (alpha < ALPHATESTVALUE)
                     discard;

packages/dev/core/src/Shaders/ShadersInclude/pbrFragmentDeclaration.fx

@@ -2,6 +2,7 @@ uniform vec4 vEyePosition;
 
 uniform vec3 vReflectionColor;
 uniform vec4 vAlbedoColor;
+uniform float baseWeight;
 
 // CUSTOM CONTROLS
 uniform vec4 vLightingIntensity;
@@ -19,6 +20,10 @@ uniform vec3 vAmbientColor;
 uniform vec2 vAlbedoInfos;
 #endif
 
+#ifdef BASEWEIGHT
+uniform vec2 vBaseWeightInfos;
+#endif
+
 #ifdef AMBIENT
 uniform vec4 vAmbientInfos;
 #endif
@@ -64,14 +69,14 @@ uniform mat4 view;
 
     #if defined(USE_LOCAL_REFLECTIONMAP_CUBIC) && defined(REFLECTIONMAP_CUBIC)
 	    uniform vec3 vReflectionPosition;
-	    uniform vec3 vReflectionSize; 
+	    uniform vec3 vReflectionSize;
     #endif
 #endif
 
 // Refraction
 #if defined(SS_REFRACTION) && defined(SS_USE_LOCAL_REFRACTIONMAP_CUBIC)
     uniform vec3 vRefractionPosition;
-    uniform vec3 vRefractionSize; 
+    uniform vec3 vRefractionSize;
 #endif
 
 // Clear Coat

packages/dev/core/src/Shaders/ShadersInclude/pbrFragmentSamplersDeclaration.fx

@@ -1,4 +1,5 @@
 #include<samplerFragmentDeclaration>(_DEFINENAME_,ALBEDO,_VARYINGNAME_,Albedo,_SAMPLERNAME_,albedo)
+#include<samplerFragmentDeclaration>(_DEFINENAME_,BASEWEIGHT,_VARYINGNAME_,BaseWeight,_SAMPLERNAME_,baseWeight)
 #include<samplerFragmentDeclaration>(_DEFINENAME_,AMBIENT,_VARYINGNAME_,Ambient,_SAMPLERNAME_,ambient)
 #include<samplerFragmentDeclaration>(_DEFINENAME_,OPACITY,_VARYINGNAME_,Opacity,_SAMPLERNAME_,opacity)
 #include<samplerFragmentDeclaration>(_DEFINENAME_,EMISSIVE,_VARYINGNAME_,Emissive,_SAMPLERNAME_,emissive)
@@ -42,7 +43,7 @@
         #define sampleReflection(s, c) textureCube(s, c)
 
         uniform samplerCube reflectionSampler;
-        
+
         #ifdef LODBASEDMICROSFURACE
             #define sampleReflectionLod(s, c, l) textureCubeLodEXT(s, c, l)
         #else
@@ -88,7 +89,7 @@
     #ifdef SS_REFRACTION
         #ifdef SS_REFRACTIONMAP_3D
             #define sampleRefraction(s, c) textureCube(s, c)
-            
+
             uniform samplerCube refractionSampler;
 
             #ifdef LODBASEDMICROSFURACE
@@ -99,7 +100,7 @@
             #endif
         #else
             #define sampleRefraction(s, c) texture2D(s, c)
-            
+
             uniform sampler2D refractionSampler;
 
             #ifdef LODBASEDMICROSFURACE