Added TexturePadding utility

ScriptableRenderPipeline/Core/CoreRP/CoreResources/TexturePadding.compute

+#include "CoreRP/ShaderLibrary/Common.hlsl"
+
+#define DIRECTION_TOPRIGHT 0
+#define DIRECTION_TOP 1
+#define DIRECTION_RIGHT 2
+
+#pragma kernel KMainTopRight            KERNEL_NAME=KMainTopRight   DIRECTION=DIRECTION_TOPRIGHT
+#pragma kernel KMainTop                 KERNEL_NAME=KMainTop        DIRECTION=DIRECTION_TOP
+#pragma kernel KMainRight               KERNEL_NAME=KMainRight      DIRECTION=DIRECTION_RIGHT
+
+#pragma only_renderers d3d11 ps4 xboxone vulkan metal
+
+// ------------------------------------------------
+// Texture buffers
+// ------------------------------------------------
+
+RW_TEXTURE2D(float4, _Source);
+
+// ------------------------------------------------
+// Constant buffers
+// ------------------------------------------------
+CBUFFER_START(cb)
+    int2 _RectOffset;
+CBUFFER_END
+
+// ------------------------------------------------
+// Kernel
+// ------------------------------------------------
+
+[numthreads(1, 1, 1)]
+void KERNEL_NAME(uint2 dispatchThreadId : SV_DispatchThreadID)
+{
+    const int2 targetId = _RectOffset + dispatchThreadId;
+
+#if DIRECTION == DIRECTION_TOPRIGHT
+    const int2 loadId = targetId - int2(1 + dispatchThreadId.x, 1 + dispatchThreadId.y);
+#elif DIRECTION == DIRECTION_TOP
+    const int2 loadId = targetId - int2(0, 1 + dispatchThreadId.y);
+#elif DIRECTION == DIRECTION_RIGHT
+    const int2 loadId = targetId - int2(1 + dispatchThreadId.x, 0);
+#endif
+
+   _Source[targetId] = LOAD_TEXTURE2D_LOD(_Source, loadId, 0);
+}

ScriptableRenderPipeline/Core/CoreRP/CoreResources/TexturePadding.compute.meta

+fileFormatVersion: 2
+guid: 6736f53014c69f84aa2130aeae99730b
+ComputeShaderImporter:
+  externalObjects: {}
+  currentAPIMask: 262148
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

ScriptableRenderPipeline/Core/CoreRP/CoreResources/TexturePadding.cs

+using System;
+using System.Collections.Generic;
+using UnityEngine.Rendering;
+
+namespace UnityEngine.Experimental.Rendering
+{
+    public class TexturePadding
+    {
+        static readonly int _RectOffset = Shader.PropertyToID("_RectOffset");
+        static readonly int _Source = Shader.PropertyToID("_Source");
+
+        ComputeShader m_CS;
+        int m_KMainTopRight;
+        int m_KMainTop;
+        int m_KMainRight;
+
+        public TexturePadding(ComputeShader cs)
+        {
+            m_CS = cs;
+            m_KMainTopRight     = m_CS.FindKernel("KMainTopRight");
+            m_KMainTop          = m_CS.FindKernel("KMainTop");
+            m_KMainRight        = m_CS.FindKernel("KMainRight");
+        }
+        public void Pad(CommandBuffer cmd, RTHandle source, RectInt from, RectInt to)
+        {
+            if (from.width < to.width)
+            {
+                cmd.SetComputeIntParams(m_CS, _RectOffset, from.width, 0);
+                cmd.SetComputeTextureParam(m_CS, m_KMainRight, _Source, source);
+                cmd.DispatchCompute(m_CS, m_KMainRight, to.width - from.width, from.height, 1);
+            }
+            if (from.height < to.height)
+            {
+                cmd.SetComputeIntParams(m_CS, _RectOffset, 0, from.height);
+                cmd.SetComputeTextureParam(m_CS, m_KMainTop, _Source, source);
+                cmd.DispatchCompute(m_CS, m_KMainTop, from.width, to.height - from.height, 1);
+            }
+            if (from.width < to.width && from.height < to.height)
+            {
+                cmd.SetComputeIntParams(m_CS, _RectOffset, from.width, from.height);
+                cmd.SetComputeTextureParam(m_CS, m_KMainTopRight, _Source, source);
+                cmd.DispatchCompute(m_CS, m_KMainTopRight, to.width - from.width, to.height - from.height, 1);
+            }
+        }
+    }
+}

ScriptableRenderPipeline/Core/CoreRP/CoreResources/TexturePadding.cs.meta

+fileFormatVersion: 2
+guid: 51c4121b1f8d7e142931a35917400cb1
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: