docs: add plugin setup guide

plugin/lib/commonlibf4/include/Scaleform/G/GFx_StateBag.h

@@ -0,0 +1,50 @@
+#pragma once
+
+#include "Scaleform/G/GFx_FileTypeConstants.h"
+#include "Scaleform/G/GFx_State.h"
+
+namespace Scaleform::GFx
+{
+	class __declspec(novtable) StateBag :
+		public FileTypeConstants  // 00
+	{
+	protected:
+		// add
+		virtual StateBag* GetStateBagImpl() const { return nullptr; }  // 00
+
+	public:
+		virtual ~StateBag() = default;  // 01
+
+		// NOLINTNEXTLINE(misc-no-recursion)
+		virtual void SetState(State::StateType a_stateType, State* a_state)  // 02
+		{
+			assert(a_state ? true : a_state->GetStateType() == a_stateType);
+			const auto bag = GetStateBagImpl();
+			if (bag) {
+				bag->SetState(a_stateType, a_state);
+			}
+		}
+
+		// NOLINTNEXTLINE(misc-no-recursion)
+		virtual State* GetStateAddRef(State::StateType a_stateType) const  // 03
+		{
+			const auto bag = GetStateBagImpl();
+			return bag ? bag->GetStateAddRef(a_stateType) : nullptr;
+		}
+
+		virtual void GetStatesAddRef(State** a_states, const State::StateType* a_stateTypes, std::uint32_t a_count) const  // 04
+		{
+			const auto bag = GetStateBagImpl();
+			if (bag) {
+				bag->GetStatesAddRef(a_states, a_stateTypes, a_count);
+			}
+		}
+
+		template <class T>
+		T* GetStateAddRef() const
+		{
+			return static_cast<T*>(GetStateAddRef(T::GFX_STATE_TYPE));
+		}
+	};
+	static_assert(sizeof(StateBag) == 0x8);
+}