HDRenderLoop: First draft not working of depth pixel offset

Assets/ScriptableRenderLoop/HDRenderLoop/Debug/Resources/DebugViewMaterialGBuffer.shader

 
             float4 Frag(Varyings input) : SV_Target
             {
-				float4 unPositionSS = input.positionCS; // as input we have the vpos
+				float4 unPositionSS = input.positionCS; // input.positionCS is SV_Position
 				Coordinate coord = GetCoordinate(unPositionSS.xy, _ScreenSize.zw);
 
                 float depth = LOAD_TEXTURE2D(_CameraDepthTexture, coord.unPositionSS).x;

Assets/ScriptableRenderLoop/HDRenderLoop/Lighting/Resources/Deferred.shader

 
             float4 Frag(Varyings input) : SV_Target
             {
-				float4 unPositionSS = input.positionCS; // as input we have the vpos
+				float4 unPositionSS = input.positionCS; // input.positionCS is SV_Position
                 Coordinate coord = GetCoordinate(unPositionSS.xy, _ScreenSize.zw);
 
                 // No need to manage inverse depth, this is handled by the projection matrix

Assets/ScriptableRenderLoop/HDRenderLoop/Material/Attributes.hlsl

 
 struct FragInput
 {
-    float4 unPositionSS; // This is the position return by VPOS (That is name positionCS in PackedVarying), only xy is use
+    // Contain value return by SV_POSITION (That is name positionCS in PackedVarying).
+    // xy: unormalized screen position at pixel center, z: device depth, w: depth in view space
+    float4 unPositionSS; // In case depth offset is use, positionWS.w is equal to depth offset
     float3 positionWS;
     float2 texCoord0;
     float2 texCoord1;
     float4 vertexColor;
 
-    // For velocity
-    // Note: Z component is not use
-    float4 positionCS; // This is the clip spae position. Warning, do not confuse with the value of positionCS in PackedVarying which is VPOS and store in unPositionSS
+    // CAUTION: Only use with velocity currently, null else
+    // Note: Z component is not use currently
+    // This is the clip space position. Warning, do not confuse with the value of positionCS in PackedVarying which is SV_POSITION and store in unPositionSS
+    float4 positionCS;
+    // end velocity specific
+
+float applyDepthOffsetToFragInput(float depthOffset, inout FragInput fragInput)
+{
+    fragInput.unPositionSS.w += depthOffset;
+    fragInput.positionCS.w += depthOffset;
+    fragInput.previousPositionCS.w += depthOffset;
+
+    return 
+}
 
 void GetVaryingsDataDebug(uint paramId, FragInput input, inout float3 result, inout bool needLinearToSRGB)
 {

Assets/ScriptableRenderLoop/HDRenderLoop/Material/Builtin/BuiltinData.cs

             public Vector2 distortion;
             [SurfaceDataAttributes("Distortion Blur")]
             public float distortionBlur;           // Define the color buffer mipmap level to use
+
+            // Depth
+            [SurfaceDataAttributes("Depth Offset")]
+            public float depthOffset; // define the depth in unity unit to add in Z forward direction
         };
 
         //-----------------------------------------------------------------------------

Assets/ScriptableRenderLoop/HDRenderLoop/Material/Builtin/BuiltinData.cs.hlsl

 #define DEBUGVIEW_BUILTIN_BUILTINDATA_VELOCITY (104)
 #define DEBUGVIEW_BUILTIN_BUILTINDATA_DISTORTION (105)
 #define DEBUGVIEW_BUILTIN_BUILTINDATA_DISTORTION_BLUR (106)
+#define DEBUGVIEW_BUILTIN_BUILTINDATA_DEPTH_OFFSET (107)
 
 //
 // UnityEngine.Experimental.ScriptableRenderLoop.Builtin.LighTransportData:  static fields
 	float2 velocity;
 	float2 distortion;
 	float distortionBlur;
+	float depthOffset;
 };
 
 // Generated from UnityEngine.Experimental.ScriptableRenderLoop.Builtin.LighTransportData

Assets/ScriptableRenderLoop/HDRenderLoop/Material/Builtin/BuiltinData.hlsl

     case DEBUGVIEW_BUILTIN_BUILTINDATA_DISTORTION_BLUR:
         result = builtinData.distortionBlur.xxx;
         break;
+    case DEBUGVIEW_BUILTIN_BUILTINDATA_DEPTH_OFFSET:
+        result = builtinData.depthOffset.xxx * 10.0; // * 10 assuming 1 unity unity is 1m
+        break;
     }
 }
 

Assets/ScriptableRenderLoop/HDRenderLoop/Material/Lit/LitDepthPass.hlsl

     FragInput output;
     ZERO_INITIALIZE(FragInput, output);
 
-    output.unPositionSS = input.positionCS;  // as input we have the vpos
+    output.unPositionSS = input.positionCS; // input.positionCS is SV_Position
 
 #if NEED_TANGENT_TO_WORLD
     output.positionWS.xyz = input.interpolators[0].xyz;

Assets/ScriptableRenderLoop/HDRenderLoop/Material/Lit/LitMetaPass.hlsl

     FragInput output;
     ZERO_INITIALIZE(FragInput, output);
 
-    output.unPositionSS = input.positionCS;  // as input we have the vpos
+    output.unPositionSS = input.positionCS;  // input.positionCS is SV_Position
     output.texCoord0 = input.interpolators[0].xy;
     output.texCoord1 = input.interpolators[0].zw;
 

Assets/ScriptableRenderLoop/HDRenderLoop/Material/Lit/LitSharePass.hlsl

     FragInput output;
     ZERO_INITIALIZE(FragInput, output);
 
-    output.unPositionSS = input.positionCS;  // as input we have the vpos
+    output.unPositionSS = input.positionCS; // input.positionCS is SV_Position
     output.positionWS.xyz = input.interpolators[0].xyz;
     output.tangentToWorld[0] = input.interpolators[1].xyz;
     output.tangentToWorld[1] = input.interpolators[2].xyz;

Assets/ScriptableRenderLoop/HDRenderLoop/Material/Lit/LitVelocityPass.hlsl

     FragInput output;
     ZERO_INITIALIZE(FragInput, output);
 
-    output.unPositionSS = input.positionCS;  // as input we have the vpos
+    output.unPositionSS = input.positionCS; // input.positionCS is SV_Position
     output.positionCS = float4(input.interpolators[0].xy, 0.0, input.interpolators[0].z);
     output.previousPositionCS = float4(input.interpolators[1].xy, 0.0, input.interpolators[1].z);
 

Assets/ScriptableRenderLoop/HDRenderLoop/ShaderVariables.hlsl

     return glstate_matrix_modelview0;
 }
 
+float4x4 GetViewToProjectionMatrix()
+{
+   //... return glstate_matrix_modelview0;
+}
+
 float3 TransformWorldToView(float3 positionWS)
 {
     return mul(GetWorldToViewMatrix(), float4(positionWS, 1.0)).xyz;

Assets/ScriptableRenderLoop/ShaderLibrary/Common.hlsl

 // This function is use to provide an easy way to sample into a screen texture, either from a pixel or a compute shaders.
 // This allow to easily share code.
 // If a compute shader call this function unPositionSS is an integer usually calculate like: uint2 unPositionSS = groupId.xy * BLOCK_SIZE + groupThreadId.xy
-// else it is current unormalized screen coordinate like return by VPOS
+// else it is current unormalized screen coordinate like return by SV_Position
 Coordinate GetCoordinate(float2 unPositionSS, float2 invScreenSize)
 {
     Coordinate coord;