feat: performance overlay

src/DX12SwapChain.cpp

@@ -176,6 +176,29 @@ HRESULT DX12SwapChain::GetDevice(REFIID uuid, void** ppDevice)
 	return swapChain->GetDevice(uuid, ppDevice);
 }
 
+float DX12SwapChain::GetFrameTime() const
+{
+	// Calculate frame time based on swap chain presentation
+	static float lastPresentTime = 0.0f;
+	static float frameTime = 1.0f / 60.0f;  // Default to 60 fps
+	static LARGE_INTEGER frequency = {};
+	static LARGE_INTEGER currentTime = {};
+
+	if (frequency.QuadPart == 0) {
+		QueryPerformanceFrequency(&frequency);
+	}
+
+	QueryPerformanceCounter(&currentTime);
+	float time = static_cast<float>(currentTime.QuadPart) / static_cast<float>(frequency.QuadPart);
+
+	if (lastPresentTime > 0.0f) {
+		frameTime = time - lastPresentTime;
+	}
+	lastPresentTime = time;
+
+	return frameTime;
+}
+
 WrappedResource::WrappedResource(D3D11_TEXTURE2D_DESC a_texDesc, ID3D11Device5* a_d3d11Device, ID3D12Device* a_d3d12Device)
 {
 	D3D12_RESOURCE_FLAGS flags = D3D12_RESOURCE_FLAG_ALLOW_RENDER_TARGET | D3D12_RESOURCE_FLAG_ALLOW_SIMULTANEOUS_ACCESS;

src/DX12SwapChain.h

@@ -94,6 +94,9 @@ class DX12SwapChain
 
 	DXGISwapChainProxy* swapChainProxy = nullptr;
 
+	// Returns the current frame time (in seconds) for accurate FPS calculation when frame generation is active
+	float GetFrameTime() const;
+
 	void CreateD3D12Device(IDXGIAdapter* a_adapter);
 	void CreateSwapChain(IDXGIAdapter* adapter, DXGI_SWAP_CHAIN_DESC swapChainDesc);