Use SafeNormalize for normals sampled from XYZ (non-DXT5nm/ASTCnm) no… (#5356)

* Use SafeNormalize for normals sampled from XYZ (non-DXT5nm/ASTCnm) normal maps

* Update changelog

Co-authored-by: Florian Penzkofer <florian@unity3d.com>

Author: hkr

com.unity.render-pipelines.universal/CHANGELOG.md

@@ -167,6 +167,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed an issue where TerrainLit was rendering color lighter than Lit [case 1340751] (https://issuetracker.unity3d.com/product/unity/issues/guid/1340751/)
 - Fixed Camera rendering when capture action and post processing present. [case 1350313]
 - Fixed artifacts in Speed Tree 8 billboard LODs due to SpeedTree LOD smoothing/crossfading [case 1348407]
+- Fix sporadic NaN when using normal maps with XYZ-encoding [case 1351020](https://issuetracker.unity3d.com/issues/android-urp-vulkan-nan-pixels-and-bloom-post-processing-generates-visual-artifacts)
 - Support undo of URP Global Settings asset assignation (case 1342987).
 - Removed unsupported fields from Presets of Light and Camera [case 1335979].
 - Fixed graphical artefact when terrain height map is used with rendering layer mask for lighting.

com.unity.render-pipelines.universal/ShaderLibrary/ShaderVariablesFunctions.hlsl

@@ -196,12 +196,21 @@ float3 NormalizeNormalPerVertex(float3 normalWS)
 
 half3 NormalizeNormalPerPixel(half3 normalWS)
 {
+// With XYZ normal map encoding we sporadically sample normals with near-zero-length causing Inf/NaN
+#if defined(UNITY_NO_DXT5nm) && defined(_NORMALMAP)
+    return SafeNormalize(normalWS);
+#else
     return normalize(normalWS);
+#endif
 }
 
 float3 NormalizeNormalPerPixel(float3 normalWS)
 {
+#if defined(UNITY_NO_DXT5nm) && defined(_NORMALMAP)
+    return SafeNormalize(normalWS);
+#else
     return normalize(normalWS);
+#endif
 }