Implement the full screen triangle shader

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

             #include "Common.hlsl"
 
             // Note: We have fix as guidelines that we have only one deferred material (with control of GBuffer enabled). Mean a users that add a new
-            // deferred material must replace the old one here. If in the future we want to support multiple layout (cause a lot of consistency problem), 
+            // deferred material must replace the old one here. If in the future we want to support multiple layout (cause a lot of consistency problem),
- 
+
- 
+
-                float3 positionOS : POSITION;
+                uint vertexId : SV_VertexID;
             };
 
             struct Varyings
 
             Varyings Vert(Attributes input)
             {
-                // TODO: implement SV_vertexID full screen quad
-                // Lights are draw as one fullscreen quad
-                float3 positionWS = TransformObjectToWorld(input.positionOS);
-                output.positionCS = TransformWorldToHClip(positionWS);
+                // Generate a triangle in homogeneous clip space, s.t.
+			    // v0 = (-1, -1, 1), v1 = (3, -1, 1), v2 = (-1, 3, 1).
+			    output.positionCS = float4(float(input.vertexId % 2) * 4.0 - 1.0,
+			    						   float(input.vertexId / 2) * 4.0 - 1.0, 1.0, 1.0);
                 return output;
             }
 

Assets/ScriptableRenderLoop/HDRenderPipeline/Lighting/TilePass/TilePass.cs

                         m_SingleDeferredMaterial.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.One);
                         m_SingleDeferredMaterial.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.Zero);
 
-                        cmd.Blit(null, cameraColorBufferRT, m_SingleDeferredMaterial, 0);
+                        Utilities.DrawFullscreen(renderContext, m_SingleDeferredMaterial, cameraColorBufferRT, 0);
                     }
                     else
                     {

Assets/ScriptableRenderLoop/HDRenderPipeline/Utilities.cs

             cmd.Dispose();
         }
 
+        static Mesh m_ScreenSpaceTriangle = new Mesh
+        {
+            // Note: the vertex data is not actually used if the vertex shader computes vertices using 'SV_VertexID'.
+            // However, there is currently no way to bind a NULL vertex buffer.
+            vertices  = new [] { new Vector3(-1, -1, 1), new Vector3(3, -1, 1), new Vector3(-1, 3, 1) },
+            triangles = new [] { 0, 1, 2 }
+        };
+
+        // Draws a full screen triangle as a faster alternative to drawing a full-screen quad.
+        public static void DrawFullscreen(ScriptableRenderContext context, Material material, RenderTargetIdentifier colorBuffer, int shaderPassID = 0)
+        {
+            var cmd = new CommandBuffer() { name = material.GetPassName(shaderPassID) };
+            cmd.SetRenderTarget(colorBuffer);
+            cmd.DrawMesh(m_ScreenSpaceTriangle, Matrix4x4.identity, material, 0, shaderPassID);
+            context.ExecuteCommandBuffer(cmd);
+            cmd.Dispose();
+        }
+
         // Miscellanous
         public static Material CreateEngineMaterial(string shaderPath)
         {