[HDRP] Improves robustness of detail normal mapping when scale = 0 (and not using surface gradients) #6980

Author: eturquin

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -6,8 +6,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [12.1.6] - 2022-02-09
 
-Version Updated
-The version number for this package has increased due to a version update of a related graphics package.
+### Fixed
+- Fixed issue with detail normals when scale is null (case 1399548).
 
 ## [12.1.5] - 2022-01-14
 
@@ -48,6 +48,7 @@ The version number for this package has increased due to a version update of a r
 - Fixed various issues with render graph viewer when entering playmode.
 - Fixed issue with Final Image Histogram displaying a flat histogram on certain GPUs and APIs.
 - Fixed HDRP camera debug panel rendering foldout.
+- Fixed issue with detail normals when scale is null (case 1399548).
 
 ## [12.1.4] - 2021-12-07
 

com.unity.render-pipelines.high-definition/Runtime/Material/Lit/LitDataIndividualLayer.hlsl

@@ -123,7 +123,7 @@ float3 ADD_IDX(GetNormalTS)(FragInputs input, LayerTexCoord layerTexCoord, float
         #ifdef SURFACE_GRADIENT
         normalTS += detailNormalTS * detailMask;
         #else
-        normalTS = lerp(normalTS, BlendNormalRNM(normalTS, detailNormalTS), detailMask); // todo: detailMask should lerp the angle of the quaternion rotation, not the normals
+        normalTS = lerp(normalTS, BlendNormalRNM(normalTS, normalize(detailNormalTS)), detailMask); // todo: detailMask should lerp the angle of the quaternion rotation, not the normals
         #endif
     #endif
 #else