Clear coat fresnel fix (#4657)

* Working on clearcoat balancing

* Fix clearcoat energy balance.

* Make sure specularity factor is only factored in if we have specular colour with metalness enabled

* Simplify the ccReflection to a vec3.

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

@@ -17,8 +17,8 @@ vec3 combineColor() {
     ret = ret * sheenScaling + sSpecularLight + sReflection.rgb * sReflection.a;
 #endif
 #ifdef LIT_CLEARCOAT
-    float clearCoatScaling = 1.0 - ccFresnel * ccReflection.a;
-    ret = ret * clearCoatScaling + ccSpecularLight + ccReflection.rgb * ccReflection.a;
+    float clearCoatScaling = 1.0 - ccFresnel * ccSpecularity;
+    ret = ret * clearCoatScaling + (ccSpecularLight + ccReflection.rgb) * ccSpecularity;
 #endif
 
     return ret;

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

@@ -10,4 +10,9 @@ vec3 getFresnel(float cosTheta, vec3 f0) {
         return ret;
     #endif    
 }
+
+float getFresnelCC(float cosTheta) {
+    float fresnel = pow(1.0 - max(cosTheta, 0.0), 5.0);
+    return 0.04 + (1.0 - 0.04) * fresnel;
+}
 `;

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

@@ -1,9 +1,7 @@
 export default /* glsl */`
 #ifdef LIT_CLEARCOAT
-uniform float material_clearCoatReflectivity;
-
 void addReflectionCC() {
-    ccReflection += vec4(calcReflection(ccReflDirW, ccGlossiness), material_clearCoatReflectivity);
+    ccReflection += calcReflection(ccReflDirW, ccGlossiness);
 }
 #endif
 `;

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

@@ -4,6 +4,6 @@ void main(void) {
 
     #ifdef LIT_CLEARCOAT
     ccSpecularLight = vec3(0);
-    ccReflection = vec4(0);
+    ccReflection = vec3(0);
     #endif
 `;

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

@@ -1038,8 +1038,8 @@ class LitShader {
                 if (options.clearCoat) {
                     code += "    addReflectionCC();\n";
                     if (options.fresnelModel > 0) {
-                        code += "    ccFresnel = dot(dViewDirW, ccNormalW);\n";
-                        code += "    ccReflection.rgb *= getFresnel(ccFresnel, vec3(ccSpecularity));\n";
+                        code += "    ccFresnel = getFresnelCC(dot(dViewDirW, ccNormalW));\n";
+                        code += "    ccReflection.rgb *= ccFresnel;\n";
                     }  else {
                         code += "    ccFresnel = 0.0;\n";
                         code += "    ccReflection.rgb *= ccSpecularity;\n";
@@ -1311,7 +1311,7 @@ class LitShader {
         if (options.opacityFadesSpecular === false) {
             if (options.blendType === BLEND_NORMAL || options.blendType === BLEND_PREMULTIPLIED) {
                 code += "float specLum = dot((dSpecularLight + dReflection.rgb * dReflection.a), vec3( 0.2126, 0.7152, 0.0722 ));\n";
-                code += "#ifdef LIT_CLEARCOAT\n specLum += dot(ccSpecularLight * ccSpecularity + ccReflection.rgb * ccReflection.a * ccSpecularity, vec3( 0.2126, 0.7152, 0.0722 ));\n#endif\n";
+                code += "#ifdef LIT_CLEARCOAT\n specLum += dot(ccSpecularLight * ccSpecularity + ccReflection.rgb * ccSpecularity, vec3( 0.2126, 0.7152, 0.0722 ));\n#endif\n";
                 code += "dAlpha = clamp(dAlpha + gammaCorrectInput(specLum), 0.0, 1.0);\n";
             }
             code += "dAlpha *= material_alphaFade;\n";
@@ -1369,7 +1369,7 @@ class LitShader {
         if (code.includes("dAtten3")) structCode += "vec3 dAtten3;\n";
         if (code.includes("dMsdf")) structCode += "vec4 dMsdf;\n";
         if (code.includes("ccFresnel")) structCode += "float ccFresnel;\n";
-        if (code.includes("ccReflection")) structCode += "vec4 ccReflection;\n";
+        if (code.includes("ccReflection")) structCode += "vec3 ccReflection;\n";
         if (code.includes("ccReflDirW")) structCode += "vec3 ccReflDirW;\n";
         if (code.includes("ccSpecularLight")) structCode += "vec3 ccSpecularLight;\n";
         if (code.includes("ccSpecularityNoFres")) structCode += "float ccSpecularityNoFres;\n";

src/scene/materials/standard-material-options-builder.js

@@ -131,7 +131,7 @@ class StandardMaterialOptionsBuilder {
                              (stdMat.specularTint || (!stdMat.specularMap && !stdMat.specularVertexColor)) &&
                              notWhite(stdMat.specular);
 
-        const specularityFactorTint = useSpecular && stdMat.useMetalness &&
+        const specularityFactorTint = useSpecular && stdMat.useMetalnessSpecularColor &&
                                       (stdMat.specularityFactorTint || (stdMat.specularityFactor < 1 && !stdMat.specularityFactorMap));
 
         const emissiveTintColor = !stdMat.emissiveMap || (notWhite(stdMat.emissive) && stdMat.emissiveTint);
@@ -145,7 +145,7 @@ class StandardMaterialOptionsBuilder {
         options.diffuseTint = diffuseTint ? 2 : 0;
         options.specularTint = specularTint ? 2 : 0;
         options.specularityFactorTint = specularityFactorTint ? 1 : 0;
-        options.useSpecularityFactor = specularityFactorTint || !!stdMat.specularityFactorMap;
+        options.useSpecularityFactor = (specularityFactorTint || !!stdMat.specularityFactorMap) && stdMat.useMetalnessSpecularColor;
         options.useSpecularColor = useSpecularColor;
         options.metalnessTint = (stdMat.useMetalness && stdMat.metalness < 1) ? 1 : 0;
         options.glossTint = 1;

src/scene/materials/standard-material.js

@@ -701,7 +701,6 @@ class StandardMaterial extends Material {
         if (this.clearCoat > 0) {
             this._setParameter('material_clearCoat', this.clearCoat);
             this._setParameter('material_clearCoatGlossiness', this.clearCoatGlossiness);
-            this._setParameter('material_clearCoatReflectivity', this.clearCoat); // for now don't separate this
             this._setParameter('material_clearCoatBumpiness', this.clearCoatBumpiness);
         }