Merge pull request #5360 from aws-lumberyard-dev/Atom/santorac/FixedThinObjectTransmission

Fixed PBR Material Transmission ThinObject Mode

Gems/Atom/Feature/Common/Assets/ShaderLib/Atom/Features/PBR/BackLighting.azsli

@@ -50,8 +50,13 @@ float3 GetBackLighting(Surface surface, LightingData lightingData, float3 lightI
             // Thin object mode, using thin-film assumption proposed by Jimenez J. et al, 2010, "Real-Time Realistic Skin Translucency"
             // http://www.iryoku.com/translucency/downloads/Real-Time-Realistic-Skin-Translucency.pdf
 
-            result = shadowRatio ? float3(0.0, 0.0, 0.0) : TransmissionKernel(surface.transmission.thickness * transmissionParams.w, rcp(transmissionParams.xyz)) * 
+            float litRatio = 1.0 - shadowRatio;
-                           saturate(dot(-surface.normal, dirToLight)) * lightIntensity * shadowRatio;
+            if (litRatio)
+            {
+                result = TransmissionKernel(surface.transmission.thickness * transmissionParams.w, rcp(transmissionParams.xyz)) * 
+                    saturate(dot(-surface.normal, dirToLight)) * lightIntensity * litRatio;
+            }
+
             break;
     }
     

Gems/Atom/TestData/TestData/Materials/StandardPbrTestCases/015_SubsurfaceScattering_Transmission_Thin.material

@@ -0,0 +1,29 @@
+{
+    "description": "",
+    "parentMaterial": "",
+    "materialType": "Materials/Types/EnhancedPBR.materialtype",
+    "materialTypeVersion": 4,
+    "properties": {
+        "baseColor": {
+            "color": [
+                0.027664607390761375,
+                0.1926604062318802,
+                0.013916227966547012,
+                1.0
+            ]
+        },
+        "general": {
+            "doubleSided": true
+        },
+        "subsurfaceScattering": {
+            "thickness": 0.20000000298023224,
+            "transmissionMode": "ThinObject",
+            "transmissionTint": [
+                0.009140154346823692,
+                0.19806210696697235,
+                0.01095597818493843,
+                1.0
+            ]
+        }
+    }
+}