Slightly faster octahedron packing and ViewReflectionNormal

ScriptableRenderPipeline/Core/ShaderLibrary/CommonLighting.hlsl

 
     NdotV = dot(N, V);
 
-    N = (NdotV >= 0.0) ? N : (N - 2.0 * NdotV * V);
+    // N = (NdotV >= 0.0) ? N : (N - 2.0 * NdotV * V);
+    N += (2.0 * saturate(-NdotV)) * V;
     NdotV = abs(NdotV);
 
     return N;

ScriptableRenderPipeline/Core/ShaderLibrary/Packing.hlsl

 // Ref: http://jcgt.org/published/0003/02/01/paper.pdf
 // Encode with Oct, this function work with any size of output
 // return float between [-1, 1]
-float2 PackNormalOctEncode(float3 n)
-{
-    float l1norm    = dot(abs(n), 1.0);
-    float2 res0     = n.xy * (1.0 / l1norm);
-
-    float2 val      = 1.0 - abs(res0.yx);
-    return (n.zz < float2(0.0, 0.0) ? (res0 >= 0.0 ? val : -val) : res0);
+float2 PackNormalOctEncode(float3 n)
+{
+    //float l1norm    = dot(abs(n), 1.0);
+    //float2 res0     = n.xy * (1.0 / l1norm);
+
+    //float2 val      = 1.0 - abs(res0.yx);
+    //return (n.zz < float2(0.0, 0.0) ? (res0 >= 0.0 ? val : -val) : res0);
+
+    // Optimized version of above code:
+    n *= rcp(dot(abs(n), 1.0));
+    float t = saturate(-n.z);
+    return n.xy + (n.xy >= 0.0 ? t : -t);
 }
 
 float3 UnpackNormalOctEncode(float2 f)