Added motion vector support to Unlit

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/Unlit/ShaderPass/UnlitSharePass.hlsl

 #define ATTRIBUTES_NEED_TEXCOORD2
 #endif
 
-#if defined(_ENABLE_FOG_ON_TRANSPARENT)
+#if defined(_ENABLE_FOG_ON_TRANSPARENT) || (SHADERPASS == SHADERPASS_VELOCITY)
 #define VARYINGS_NEED_POSITION_WS
 #endif
 

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/Unlit/Unlit.shader

         [ToggleOff] _EnableFogOnTransparent("Enable Fog", Float) = 0.0
         [ToggleOff] _DoubleSidedEnable("Double sided enable", Float) = 0.0
 
+        // Stencil state
+        [HideInInspector] _StencilRef("_StencilRef", Int) = 2 // StencilLightingUsage.RegularLighting  (fixed at compile time)
+        [HideInInspector] _StencilWriteMask("_StencilWriteMask", Int) = 7 // StencilMask.Lighting  (fixed at compile time)
+        [HideInInspector] _StencilRefMV("_StencilRefMV", Int) = 128 // StencilLightingUsage.RegularLighting  (fixed at compile time)
+        [HideInInspector] _StencilWriteMaskMV("_StencilWriteMaskMV", Int) = 128 // StencilMask.ObjectsVelocity  (fixed at compile time)
+
         // Caution: C# code in BaseLitUI.cs call LightmapEmissionFlagsProperty() which assume that there is an existing "_EmissionColor"
         // value that exist to identify if the GI emission need to be enabled.
         // In our case we don't use such a mechanism but need to keep the code quiet. We declare the value and always enable it.
             #include "ShaderPass/UnlitSharePass.hlsl"
             #include "UnlitData.hlsl"
             #include "../../ShaderPass/ShaderPassLightTransport.hlsl"
+
+            ENDHLSL
+        }
+
+        Pass
+        {
+            Name "Motion Vectors"
+            Tags{ "LightMode" = "MotionVectors" } // Caution, this need to be call like this to setup the correct parameters by C++ (legacy Unity)
+
+            // If velocity pass (motion vectors) is enabled we tag the stencil so it don't perform CameraMotionVelocity
+            Stencil
+            {
+                WriteMask [_StencilWriteMaskMV]
+                Ref [_StencilRefMV]
+                Comp Always
+                Pass Replace
+            }
+
+            Cull[_CullMode]
+
+            ZWrite On
+
+            HLSLPROGRAM
+
+            #define SHADERPASS SHADERPASS_VELOCITY
+            #include "../../ShaderVariables.hlsl"
+            #include "../../Material/Material.hlsl"
+            #include "ShaderPass/UnlitSharePass.hlsl"
+            #include "UnlitData.hlsl"
+            #include "../../ShaderPass/ShaderPassVelocity.hlsl"
 
             ENDHLSL
         }

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/Unlit/UnlitData.hlsl

 //-------------------------------------------------------------------------------------
 // Fill SurfaceData/Builtin data function
 //-------------------------------------------------------------------------------------
+#include "../MaterialUtilities.hlsl"
 
 void GetSurfaceAndBuiltinData(FragInputs input, float3 V, inout PositionInputs posInput, out SurfaceData surfaceData, out BuiltinData builtinData)
 {