Light tweaks and bugfix on shader

Author: ciro-unity

UOP1_Project/Assets/Shaders/CustomHLSL/CustomLighting.hlsl

@@ -3,7 +3,7 @@
 
 void MainLight_float(float3 WorldPos, out float3 Direction, out float3 Color, out float ShadowAtten)
 {
-#if SHADERGRAPH_PREVIEW
+#if defined(SHADERGRAPH_PREVIEW)
     Direction = float3(0.5, 0.5, 0);
     Color = 1;
     ShadowAtten = 1;
@@ -31,7 +31,7 @@ void DirectSpecular_float(float Smoothness, float3 Direction, float3 WorldNormal
 {
     float4 White = 1;
 
-#if SHADERGRAPH_PREVIEW
+#if defined(SHADERGRAPH_PREVIEW)
     Out = 0;
 #else
     Smoothness = exp2(10 * Smoothness + 1);
@@ -47,7 +47,7 @@ void AdditionalLights_float(float Smoothness, float3 WorldPosition, float3 World
     float3 specularColor = 0;
     float4 White = 1;
 
-#ifndef SHADERGRAPH_PREVIEW
+#if !defined(SHADERGRAPH_PREVIEW)
     Smoothness = exp2(10 * Smoothness + 1);
     WorldNormal = normalize(WorldNormal);
     WorldView = SafeNormalize(WorldView);