Added viewDir to vertexOutput and reused the functions from Standard LWRP shader for normal and viewDirection calculation.

Added and/or fixed precision specifiers for constants.

com.unity.render-pipelines.lightweight/LWRP/ShaderLibrary/Terrain/LightweightPassLitTerrain.hlsl

     float4 uvSplat01                : TEXCOORD0; // xy: splat0, zw: splat1
     float4 uvSplat23                : TEXCOORD1; // xy: splat2, zw: splat3
     float4 uvControlAndLM           : TEXCOORD2; // xy: control, zw: lightmap
+
+#if _TERRAIN_NORMAL_MAP
+    half4 normal                    : TEXCOORD3;    // xyz: normal, w: viewDir.x
+    half4 tangent                   : TEXCOORD4;    // xyz: tangent, w: viewDir.y
+    half4 binormal                  : TEXCOORD5;    // xyz: binormal, w: viewDir.z
+#else
-#if _TERRAIN_NORMAL_MAP
-    half3 tangent                   : TEXCOORD4;
-    half3 binormal                  : TEXCOORD5;
+    half3 viewDir                   : TEXCOORD4;
+
     half4 fogFactorAndVertexLight   : TEXCOORD6; // x: fogFactor, yzw: vertex light
     float3 positionWS               : TEXCOORD7;
     float4 shadowCoord              : TEXCOORD8;
     input.positionWS = IN.positionWS;
 
 #ifdef _TERRAIN_NORMAL_MAP
-    input.normalWS = TangentToWorldNormal(normalTS, IN.tangent, IN.binormal, IN.normal);
+    half3 viewDir = half3(IN.normal.w, IN.tangent.w, IN.binormal.w);
+    input.normalWS = TangentToWorldNormal(normalTS, IN.tangent.xyz, IN.binormal.xyz, IN.normal.xyz);
-    input.normalWS = normalize(IN.normal);
+    half3 viewDir = IN.viewDir;
+    input.normalWS = FragmentNormalWS(IN.normal);
-    input.viewDirectionWS = SafeNormalize(GetCameraPositionWS() - IN.positionWS);
+    input.viewDirectionWS = FragmentViewDirWS(viewDir);
 #ifdef _SHADOWS_ENABLED
     input.shadowCoord = IN.shadowCoord;
 #else
 void SplatmapMix(VertexOutput IN, half4 defaultAlpha, out half4 splat_control, out half weight, out half4 mixedDiffuse, inout half3 mixedNormal)
 {
     splat_control = SAMPLE_TEXTURE2D(_Control, sampler_Control, IN.uvControlAndLM.xy);
-    weight = dot(splat_control, 1);
+    weight = dot(splat_control, 1.0h);
-    clip(weight == 0.0f ? -1 : 1);
+    clip(weight == 0.0h ? -1.0h : 1.0h);
-    splat_control /= (weight + 1e-3f);
+    splat_control /= (weight + 1e-3h);
-    mixedDiffuse = 0.0f;
-    mixedDiffuse += splat_control.r * SAMPLE_TEXTURE2D(_Splat0, sampler_Splat0, IN.uvSplat01.xy) * half4(1.0, 1.0, 1.0, defaultAlpha.r);
-    mixedDiffuse += splat_control.g * SAMPLE_TEXTURE2D(_Splat1, sampler_Splat0, IN.uvSplat01.zw) * half4(1.0, 1.0, 1.0, defaultAlpha.g);
-    mixedDiffuse += splat_control.b * SAMPLE_TEXTURE2D(_Splat2, sampler_Splat0, IN.uvSplat23.xy) * half4(1.0, 1.0, 1.0, defaultAlpha.b);
-    mixedDiffuse += splat_control.a * SAMPLE_TEXTURE2D(_Splat3, sampler_Splat0, IN.uvSplat23.zw) * half4(1.0, 1.0, 1.0, defaultAlpha.a);
+    mixedDiffuse = 0.0h;
+    mixedDiffuse += splat_control.r * SAMPLE_TEXTURE2D(_Splat0, sampler_Splat0, IN.uvSplat01.xy) * half4(1.0h, 1.0h, 1.0h, defaultAlpha.r);
+    mixedDiffuse += splat_control.g * SAMPLE_TEXTURE2D(_Splat1, sampler_Splat0, IN.uvSplat01.zw) * half4(1.0h, 1.0h, 1.0h, defaultAlpha.g);
+    mixedDiffuse += splat_control.b * SAMPLE_TEXTURE2D(_Splat2, sampler_Splat0, IN.uvSplat23.xy) * half4(1.0h, 1.0h, 1.0h, defaultAlpha.b);
+    mixedDiffuse += splat_control.a * SAMPLE_TEXTURE2D(_Splat3, sampler_Splat0, IN.uvSplat23.zw) * half4(1.0h, 1.0h, 1.0h, defaultAlpha.a);
 
 #ifdef _TERRAIN_NORMAL_MAP
     half4 nrm = 0.0f;
     nrm += splat_control.a * SAMPLE_TEXTURE2D(_Normal3, sampler_Normal0, IN.uvSplat23.zw);
     mixedNormal = UnpackNormal(nrm);
 #else
-    mixedNormal = half3(0, 0, 1);
+    mixedNormal = half3(0.0h, 0.0h, 1.0h);
 #endif
 }
 
-    #ifdef TERRAIN_SPLAT_ADDPASS
-        ApplyFogColor(color.rgb, half3(0,0,0), fogCoord);
-    #else
-        ApplyFog(color.rgb, fogCoord);
-    #endif
+#ifdef TERRAIN_SPLAT_ADDPASS
+    ApplyFogColor(color.rgb, half3(0.0h, 0.0h, 0.0h), fogCoord);
+#else
+    ApplyFog(color.rgb, fogCoord);
+#endif
 }
 
 ///////////////////////////////////////////////////////////////////////////////
     o.uvControlAndLM.xy = TRANSFORM_TEX(v.texcoord, _Control);
     o.uvControlAndLM.zw = v.texcoord1 * unity_LightmapST.xy + unity_LightmapST.zw;
 
+    half3 viewDir = VertexViewDirWS(GetCameraPositionWS() - positionWS.xyz);
+
-    OutputTangentToWorld(vertexTangent, v.normal, o.tangent, o.binormal, o.normal);
+    OutputTangentToWorld(vertexTangent, v.normal, o.tangent.xyz, o.binormal.xyz, o.normal.xyz);
+
+    o.normal.w = viewDir.x;
+    o.tangent.w = viewDir.y;
+    o.binormal.w = viewDir.z;
+    o.viewDir = viewDir;
 #endif
     o.fogFactorAndVertexLight.x = ComputeFogFactor(clipPos.z);
     o.fogFactorAndVertexLight.yzw = VertexLighting(positionWS, o.normal);
 #ifdef _SHADOWS_ENABLED
-#if SHADOWS_SCREEN
-    o.shadowCoord = ComputeShadowCoord(o.clipPos);
-#else
-    o.shadowCoord = TransformWorldToShadowCoord(positionWS);
-#endif
+    #if SHADOWS_SCREEN
+        o.shadowCoord = ComputeShadowCoord(o.clipPos);
+    #else
+        o.shadowCoord = TransformWorldToShadowCoord(positionWS);
+    #endif
 #endif
 
     return o;
     half3 albedo = mixedDiffuse.rgb;
     half smoothness = mixedDiffuse.a;
     half metallic = dot(splat_control, half4(_Metallic0, _Metallic1, _Metallic2, _Metallic3));
-    half3 specular = half3(0, 0, 0);
+    half3 specular = half3(0.0h, 0.0h, 0.0h);
-    half4 color = LightweightFragmentPBR(inputData, albedo, metallic, specular, smoothness, /* occlusion */ 1.0, /* emission */ half3(0, 0, 0), alpha);
+    half4 color = LightweightFragmentPBR(inputData, albedo, metallic, specular, smoothness, /* occlusion */ 1.0h, /* emission */ half3(0.0h, 0.0h, 0.0h), alpha);
-    return half4(color.rgb, 1);
+    return half4(color.rgb, 1.0h);
 }
 
 #endif // LIGHTWEIGHT_PASS_LIT_TERRAIN_INCLUDED