Fixes sheen intensity (#4697)

* Fix double clearcoat spec multiplication.

* Use CC fresnel for lights

* Use CC fresnel for lights

* Add reflection sample with base mip offset for materials

* Defer multiplication of sheen specular color to combine step.

* We don't use reciprocal PI for energy preservation, so doing it for sheen was a mistake.

Also revert the mip offset reflection sampling.
Also, sheen should not be a factor of the materials reflectivity.

src/graphics/program-lib/chunks/lit/frag/clusteredLight.js

@@ -523,14 +523,14 @@ void evaluateLight(ClusterLightData light) {
 
                 #ifdef LIT_CLEARCOAT
                     #ifdef LIT_SPECULAR_FRESNEL
-                        ccSpecularLight += getLightSpecularCC(halfDir) * dAtten * light.color * dAtten3 * getFresnel(dot(dViewDirW, halfDir), vec3(ccSpecularity));
+                        ccSpecularLight += getLightSpecularCC(halfDir) * dAtten * light.color * dAtten3 * getFresnelCC(dot(dViewDirW, halfDir));
                     #else
-                        ccSpecularLight += getLightSpecularCC(halfDir) * dAtten * light.color * dAtten3 * vec3(ccSpecularity);
+                        ccSpecularLight += getLightSpecularCC(halfDir) * dAtten * light.color * dAtten3;
                     #endif
                 #endif
 
                 #ifdef LIT_SHEEN
-                    sSpecularLight += getLightSpecularSheen(halfDir) * dAtten * light.color * dAtten3 * sSpecularity;
+                    sSpecularLight += getLightSpecularSheen(halfDir) * dAtten * light.color * dAtten3;
                 #endif
 
             #endif

src/graphics/program-lib/chunks/lit/frag/combine.js

@@ -12,9 +12,10 @@ vec3 combineColor() {
 #ifdef LIT_REFLECTIONS
     ret += dReflection.rgb * dReflection.a;
 #endif
+
 #ifdef LIT_SHEEN
     float sheenScaling = 1.0 - max(max(sSpecularity.r, sSpecularity.g), sSpecularity.b) * 0.157;
-    ret = ret * sheenScaling + sSpecularLight + sReflection.rgb * sReflection.a;
+    ret = ret * sheenScaling + (sSpecularLight + sReflection.rgb) * sSpecularity;
 #endif
 #ifdef LIT_CLEARCOAT
     float clearCoatScaling = 1.0 - ccFresnel * ccSpecularity;

src/graphics/program-lib/chunks/lit/frag/reflectionSheen.js

@@ -8,6 +8,6 @@ void addReflectionSheen() {
     float a = sGlossiness < 0.25 ? -339.2 * alphaG + 161.4 * sGlossiness - 25.9 : -8.48 * alphaG + 14.3 * sGlossiness - 9.95;
     float b = sGlossiness < 0.25 ? 44.0 * alphaG - 23.7 * sGlossiness + 3.26 : 1.97 * alphaG - 3.27 * sGlossiness + 0.72;
     float DG = exp( a * NoV + b ) + ( sGlossiness < 0.25 ? 0.0 : 0.1 * ( sGlossiness - 0.25 ) );
-    sReflection += vec4(calcReflection(dReflDirW, sGlossiness), saturate(DG * 1.0/PI));
+    sReflection += calcReflection(dNormalW, 0.0) * saturate(DG);
 }
 `;

src/graphics/program-lib/programs/lit-shader.js

@@ -1042,7 +1042,6 @@ class LitShader {
                         code += "    ccReflection.rgb *= ccFresnel;\n";
                     }  else {
                         code += "    ccFresnel = 0.0;\n";
-                        code += "    ccReflection.rgb *= ccSpecularity;\n";
                     }
                 }
                 if (options.useSpecularityFactor) {
@@ -1051,11 +1050,11 @@ class LitShader {
 
                 if (options.sheen) {
                     code += "    addReflectionSheen();\n";
-                    code += "    sReflection.rgb *= sSpecularity;\n";
                 }
 
                 // Fresnel has to be applied to reflections
                 code += "    addReflection();\n";
+
                 if (options.fresnelModel > 0) {
                     code += "    dReflection.rgb *= getFresnel(dot(dViewDirW, dNormalW), dSpecularity);\n";
                 } else {
@@ -1248,18 +1247,18 @@ class LitShader {
                     if (options.clearCoat) {
                         code += "    ccSpecularLight += getLightSpecularCC(dHalfDirW) * dAtten * light" + i + "_color";
                         code += usesCookieNow ? " * dAtten3" : "";
-                        code += calcFresnel ? " * getFresnel(dot(dViewDirW, dHalfDirW), vec3(ccSpecularity))" : " * vec3(ccSpecularity)";
+                        code += calcFresnel ? " * getFresnelCC(dot(dViewDirW, dHalfDirW))" : "";
                         code +=  ";\n";
                     }
                     if (options.sheen) {
-                        code += "    sSpecularLight += getLightSpecularSheen(dHalfDirW) * dAtten * light" + i + "_color * sSpecularity";
+                        code += "    sSpecularLight += getLightSpecularSheen(dHalfDirW) * dAtten * light" + i + "_color";
                         code += usesCookieNow ? " * dAtten3" : "";
                         code +=  ";\n";
                     }
                     if (options.useSpecular) {
                         code += "    dSpecularLight += getLightSpecular(dHalfDirW) * dAtten * light" + i + "_color";
                         code += usesCookieNow ? " * dAtten3" : "";
-                        code += calcFresnel ? " * getFresnel(dot(dViewDirW, dHalfDirW), dSpecularity)" : " * dSpecularity";
+                        code += calcFresnel ? " * getFresnel(dot(dViewDirW, dHalfDirW), dSpecularity)" : "";
                         code += ";\n";
                     }
                 }
@@ -1374,7 +1373,7 @@ class LitShader {
         if (code.includes("ccSpecularLight")) structCode += "vec3 ccSpecularLight;\n";
         if (code.includes("ccSpecularityNoFres")) structCode += "float ccSpecularityNoFres;\n";
         if (code.includes("sSpecularLight")) structCode += "vec3 sSpecularLight;\n";
-        if (code.includes("sReflection")) structCode += "vec4 sReflection;\n";
+        if (code.includes("sReflection")) structCode += "vec3 sReflection;\n";
 
         const result = this._fsGetBeginCode() +
             this.varyings +