feat: Main shader LOD detail map

Assets/_Content/Shaders/EnkiBillal/Include/EnkiBiIlal.hlsl

@@ -33,7 +33,6 @@ float3 GetScale(float3 PivotWS)
 float GetShadow(float3 PositionWS)
 {
     float4 shadowCoord = TransformWorldToShadowCoord(PositionWS);
-
     Light mainLight = GetMainLight(shadowCoord);
 
     float shadow = 1 - mainLight.shadowAttenuation;
@@ -52,6 +51,31 @@ float GetShadow(float3 PositionWS)
     return saturate(shadow);
 }
 
+void GetDetailLOD
+(
+    float Depth,
+    float DetailSize,
+    float LODJitter,
+    out float DetailSizeA,
+    out float DetailSizeB,
+    out float LODBlend
+)
+{
+    const float lodRatio = 4;
+    const float lodSize = DetailSize / lodRatio * 2;
+
+    float dist = max(Depth, 1e-5);
+    float lod = log(dist) / log(lodRatio) + LODJitter; // log2(dist);
+
+    float lodFloor = floor(lod);
+    float lodFrac = lod - lodFloor;
+
+    LODBlend = lodFrac * lodFrac * (3 - 2 * lodFrac);
+
+    DetailSizeA = lodSize * pow(lodRatio, lodFloor);
+    DetailSizeB = lodSize * pow(lodRatio, lodFloor + 1);
+}
+
 float4 SampleBombedTexture
 (
     UnityTexture2D Tex,
@@ -116,7 +140,7 @@ ProjectionData GetProjections
 (
     float3 PositionOS,
     float3 NormalOS,
-    float Blend
+    float ProjectionBlend
 )
 {
     ProjectionData data;
@@ -134,7 +158,7 @@ ProjectionData GetProjections
         float3(0, 0, 1)
     };
 
-    float sharpness = lerp(2, 32, saturate(Blend));
+    float sharpness = lerp(2, 32, saturate(ProjectionBlend));
 
     float maskSum = 0;
 
@@ -171,6 +195,69 @@ ProjectionData GetProjections
     return data;
 }
 
+float4 SampleProjectedDetailLOD
+(
+    UnityTexture2D DetailTex,
+    float3 PositionOS,
+    float3 NormalOS,
+    float ProjectionBlend,
+    float DetailSize,
+    float Depth
+)
+{
+    const float lodJitterStrength = .8;
+    const float lodJitterSize = 1.5;
+
+    float4 detail = 0;
+    float totalMask = 0;
+
+    ProjectionData projections = GetProjections
+    (
+        PositionOS,
+        NormalOS,
+        ProjectionBlend
+    );
+
+    [unroll]
+    for (int i = 0; i < 7; i++)
+    {
+        float mask = projections.mask[i];
+
+        float lodJitter = (Hash1From2D(floor(projections.uv[i] * lodJitterSize) + i * 17.13) - .5) * lodJitterStrength;
+
+        float detailSizeA;
+        float detailSizeB;
+        float lodBlend;
+
+        GetDetailLOD
+        (
+            Depth,
+            DetailSize,
+            lodJitter,
+            detailSizeA,
+            detailSizeB,
+            lodBlend
+        );
+
+        float4 detailA = SampleBombedTexture
+        (
+            DetailTex,
+            projections.uv[i] / detailSizeA
+        );
+
+        float4 detailB = SampleBombedTexture
+        (
+            DetailTex,
+            projections.uv[i] / detailSizeB
+        );
+
+        detail += lerp(detailA, detailB, lodBlend) * mask;
+        totalMask += mask;
+    }
+
+    return detail / max(totalMask, 1e-5);
+}
+
 void EnkiBillal_float
 (
     float4 Color,
@@ -179,6 +266,10 @@ void EnkiBillal_float
     float3 PositionWS,
     float3 NormalWS,
     float ProjectionsBlend,
+    float DetailSize,
+    float4 FogColor,
+    float FogMin,
+    float FogMax,
     out float3 Output
 )
 {
@@ -201,38 +292,26 @@ void EnkiBillal_float
 
     // Detail
     
-    float4 detail = 0;
-
-    ProjectionData projections = GetProjections
+    float4 detail = SampleProjectedDetailLOD
     (
+        DetailTex,
         positionOS,
         normalOS,
-        ProjectionsBlend
+        ProjectionsBlend,
+        DetailSize,
+        depth
+    
     );
-
-    float totalMask = 0;
-
-    [unroll]
-    for (int i = 0; i < 7; i++)
-    {
-        float mask = projections.mask[i];
-
-        detail += SampleBombedTexture
-        (
-            DetailTex,
-            projections.uv[i]
-        ) * mask;
-
-        totalMask += mask;
-    }
-
-    detail /= max(totalMask, 1e-5);
+    
+    float detailMask = smoothstep(0, .8, detail.a);
+    
+    // Fog
     
     // Output
     
     Output = Color.rgb;
-    Output = lerp(Color.rgb, Color.rgb * detail.rgb, detail.a);
-    //Output *= shadowAtten;
+    Output = lerp(Output.rgb, detail.rgb, detailMask);
+    Output = lerp(Output.rgb, FogColor.rgb, smoothstep(FogMin, FogMax, depth) * FogColor.a);
 }
 
 #endif