HDRenderLoop: Fixed issue with velocity pass + fix shader warning

- GBuffer velocity can't work as we miss prevPosition Attribute in
GBuffer pass
- #define can't be include in C# from another file...

Assets/ScriptableRenderLoop/HDRenderLoop/HDRenderLoop.asset.meta

 fileFormatVersion: 2
 guid: 2400b74f5ce370c4481e5dc417d03703
-timeCreated: 1478740672
+timeCreated: 1478744315
 licenseType: Pro
 NativeFormatImporter:
   userData: 

Assets/ScriptableRenderLoop/HDRenderLoop/HDRenderLoop.cs

+// Must be in sync with ShaderConfig.cs
+//#define VELOCITY_IN_GBUFFER
+
 using UnityEngine.Rendering;
 using UnityEngine.Experimental.Rendering;
 using System.Collections.Generic;
             // In forward we still name the buffer as if they were gbuffer, it doesn't matter            
             for (int gbufferIndex = 0; gbufferIndex < m_BuiltinRenderLoop.GetGBufferCount(); ++gbufferIndex)
             {
-                m_gbufferManager.SetBufferDescription(m_gbufferManager.gbufferCount + gbufferIndex, "_CameraGBufferTexture" + gbufferIndex, m_BuiltinRenderLoop.RTFormat[gbufferIndex], m_BuiltinRenderLoop.RTReadWrite[gbufferIndex]);
+                int textureIndex = m_gbufferManager.gbufferCount + gbufferIndex;
+                m_gbufferManager.SetBufferDescription(textureIndex, "_CameraGBufferTexture" + textureIndex, m_BuiltinRenderLoop.RTFormat[gbufferIndex], m_BuiltinRenderLoop.RTReadWrite[gbufferIndex]);
+            // Caution velocity texture name must match with Macro in Material.hlsl
             s_VelocityBuffer = Shader.PropertyToID("_VelocityTexture");
             #if VELOCITY_IN_GBUFFER
             m_gbufferManager.SetBufferDescription(m_gbufferManager.gbufferCount, "_VelocityTexture", m_BuiltinRenderLoop.GetVelocityBufferFormat(), m_BuiltinRenderLoop.GetVelocityBufferReadWrite());
                     // but when they are forward they should render a second time here in velocity pass... Maybe we should enable MRT during forward pass ?
                     // TODO: implement MRT velocity buffer as an option in case of forward
                     // Render as late as possible to benefit from an up to date depth buffer (TODO: could use equal depth test ?)
-#if VELOCITY_IN_GBUFFER
+                    #if VELOCITY_IN_GBUFFER
-#endif
+                    #endif
                         RenderVelocity(cullResults, camera, renderLoop);
 
                     FinalPass(renderLoop);

Assets/ScriptableRenderLoop/HDRenderLoop/Shaders/Material/LayeredLit/LayeredLitDefault.shader

         Tags { "RenderType"="Opaque" "PerformanceChecks"="False" }
         LOD 300
 
-        // ------------------------------------------------------------------
-        //  Deferred pass
-        Pass
+       Pass
         {
             Name "GBuffer"  // Name is not used
             Tags { "LightMode" = "GBuffer" } // This will be only for opaque object based on the RenderQueue index
             ENDHLSL
         }
 
-        // ------------------------------------------------------------------
-        //  Debug pass
         Pass
         {
             Name "Debug"
             ENDHLSL
         }
 
-        // ------------------------------------------------------------------
-        // ------------------------------------------------------------------
         Pass
         {
             Name "META"
             ENDHLSL
         }
 
-        // ------------------------------------------------------------------
-        //  Depth only
-        // ------------------------------------------------------------------
+        Pass
+        {
+            Name "Motion Vectors"
+            Tags{ "LightMode" = "MotionVectors" } // Caution, this need to be call like this to setup the correct parameters by C++ (legacy Unity)
+
+            Cull[_CullMode]
+
+            ZTest LEqual
+            ZWrite Off // TODO: Test Z equal here.
+
+            HLSLPROGRAM
+
+            #pragma vertex Vert
+            #pragma fragment Frag
+
+            #define SHADERPASS SHADERPASS_VELOCITY
+            #define LAYERED_LIT_SHADER
+            #include "../../Material/Material.hlsl"         
+            #include "../Lit/LitData.hlsl"
+            #include "../Lit/LitVelocityPass.hlsl"
+
+            #include "../../ShaderPass/ShaderPassVelocity.hlsl"
+
+            ENDHLSL
+        }
+
         Pass
         {
             Name "ShadowCaster"
             ENDHLSL
         }
 
-        // ------------------------------------------------------------------
-        //  forward pass
         Pass
         {
             Name "Forward" // Name is not used

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

 {
     PackedVaryings output;
     output.positionCS = input.positionCS;
-    output.interpolators[0].xyz = float4(input.transferPositionCS.xyw, 0.0);
-    output.interpolators[1].xyz = float4(input.transferPreviousPositionCS.xyw, 0.0);
+    output.interpolators[0] = float4(input.transferPositionCS.xyw, 0.0);
+    output.interpolators[1] = float4(input.transferPreviousPositionCS.xyw, 0.0);
 
 #if NEED_TANGENT_TO_WORLD
     output.interpolators[0].w = input.texCoord0.x;
     output.positionCS = TransformWorldToHClip(positionWS);
 
     // TODO: Clean this code, put in function ?
-    output.transferPositionCS = mul(_NonJitteredVP, mul(unity_ObjectToWorld, input.positionOS));
-    output.transferPreviousPositionCS = mul(_PreviousVP, mul(_PreviousM, _HasLastPositionData ? float4(input.previousPositionOS, 1.0) : input.positionOS));
+    output.transferPositionCS = mul(_NonJitteredVP, mul(unity_ObjectToWorld, float4(input.positionOS, 1.0)));
+    output.transferPreviousPositionCS = mul(_PreviousVP, mul(_PreviousM, _HasLastPositionData ? float4(input.previousPositionOS, 1.0) : float4(input.positionOS, 1.0)));
 
 #if NEED_TEXCOORD0
     output.texCoord0 = input.uv0;

Assets/ScriptableRenderLoop/HDRenderLoop/Shaders/Material/Material.hlsl

 
 #endif // #ifdef GBUFFERMATERIAL_COUNT
 
-// Decode velocity need to be accessible in both forward and deferred
-#ifdef VELOCITY_IN_GBUFFER
-#define DECODE_VELOCITY_BUFFER(NAME) DecodeVelocity(GBUFFER_VELOCITY_NAME(NAME))
-#else
-#define DECODE_VELOCITY_BUFFER(NAME) DecodeVelocity(GBUFFER_VELOCITY_NAME(NAME))
-#endif
-
 #endif // UNITY_MATERIAL_INCLUDED

Assets/ScriptableRenderLoop/HDRenderLoop/Shaders/ShaderConfig.cs

 // #define DIFFUSE_LAMBERT_BRDF
 // #define USE_BSDF_PRE_LAMBDAV
 
-// Caution: If you change one of the define below you need to regenerate the hlsl code (Push Generate Shader Includes)
+// Note: C# define can't be reuse in another C# file and ideally we would like that these define are present both on C# and HLSL side... How to do that ?
+// For now sync by hand within HDRenderLoop.cs file and this one
 // TODO: Currently it is not yet possible to use this feature, we need to provide previousPositionCS to the vertex shader as part of Attribute for GBuffer pass
 //#define VELOCITY_IN_GBUFFER