[Backport 7.x.x] Fix NaN cause when a 0-length normal is generated and then normalized

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

@@ -59,6 +59,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed unneeded cookie texture allocation for cone stop lights.
 - Fixed issue when toggling anything in HDRP asset that will produce an error (case 1238155)
 - Diffusion Profile and Material references in HDRP materials are now correctly exported to unity packages. Note that the diffusion profile or the material references need to be edited once before this can work properly.
+- Fixed a cause of NaN when a normal of 0-length is generated (usually via shadergraph).
 
 ### Changed
 - Rejecting history for ray traced reflections based on a threshold evaluated on the neighborhood of the sampled history.

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

@@ -32,8 +32,8 @@ void GetNormalWS(FragInputs input, float3 normalTS, out float3 normalWS, float3
     normalTS.xy *= flipSign;
 #endif // _DOUBLESIDED_ON
 
-    // We need to normalize as we use mikkt tangent space and this is expected (tangent space is not normalize)
-    normalWS = normalize(TransformTangentToWorld(normalTS, input.tangentToWorld));
+    // We need to normalize as we use mikkt tangent space and this is expected (tangent space is not normalized)
+    normalWS = SafeNormalize(TransformTangentToWorld(normalTS, input.tangentToWorld));
 
 #endif // SURFACE_GRADIENT
 }

com.unity.shadergraph/Editor/Data/Nodes/Artistic/Normal/NormalBlendNode.cs

@@ -58,7 +58,7 @@ static string Unity_NormalBlend(
 
             return @"
 {
-    Out = normalize($precision3(A.rg + B.rg, A.b * B.b));
+    Out = SafeNormalize($precision3(A.rg + B.rg, A.b * B.b));
 }
 ";
         }

com.unity.shadergraph/Editor/Data/Nodes/Artistic/Normal/NormalFromHeightNode.cs

@@ -91,7 +91,7 @@ public void GenerateNodeFunction(FunctionRegistry registry, GenerationMode gener
                         s.AppendLine("$precision3 inToNormal = ((((In + ddx(In)) - In) * crossY) + (((In + ddy(In)) - In) * crossX)) * sign(d);");
                         s.AppendLine("inToNormal.y *= -1.0;");
                         s.AppendNewLine();
-                        s.AppendLine("Out = normalize((d * TangentMatrix[2].xyz) - inToNormal);");
+                        s.AppendLine("Out = SafeNormalize((d * TangentMatrix[2].xyz) - inToNormal);");
 
                         if(outputSpace == OutputSpace.Tangent)
                             s.AppendLine("Out = TransformWorldToTangent(Out, TangentMatrix);");