Implement D3D12 backend

Source/Core/VideoBackends/D3D12/DXVertexFormat.h

@@ -0,0 +1,33 @@
+// Copyright 2019 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <array>
+#include <d3d12.h>
+
+#include "Common/CommonTypes.h"
+#include "VideoCommon/NativeVertexFormat.h"
+
+namespace DX12
+{
+class DXVertexFormat : public NativeVertexFormat
+{
+public:
+  static const u32 MAX_VERTEX_ATTRIBUTES = 16;
+
+  DXVertexFormat(const PortableVertexDeclaration& vtx_decl);
+
+  // Passed to pipeline state creation
+  void GetInputLayoutDesc(D3D12_INPUT_LAYOUT_DESC* desc) const;
+
+private:
+  void AddAttribute(const char* semantic_name, u32 semantic_index, u32 slot, DXGI_FORMAT format,
+                    u32 offset);
+  void MapAttributes();
+
+  std::array<D3D12_INPUT_ELEMENT_DESC, MAX_VERTEX_ATTRIBUTES> m_attribute_descriptions = {};
+  u32 m_num_attributes = 0;
+};
+}  // namespace Vulkan