fix: refresh d3d12 swapchain backbuffers on resize

engine/include/XCEngine/RHI/D3D12/D3D12SwapChain.h

@@ -33,6 +33,9 @@ public:
     void* GetNativeHandle() override;
 
 private:
+    bool RefreshBackBuffers();
+    void ReleaseBackBuffers();
+
     ComPtr<IDXGISwapChain3> m_swapChain;
     ComPtr<ID3D12CommandQueue> m_commandQueue;
     uint32_t m_width;

engine/src/RHI/D3D12/D3D12SwapChain.cpp

@@ -43,14 +43,7 @@ bool D3D12SwapChain::Initialize(IDXGIFactory4* factory, ID3D12CommandQueue* comm
     m_height = height;
     m_bufferCount = bufferCount;
 
-    m_backBuffers.resize(m_bufferCount);
-    for (uint32_t i = 0; i < m_bufferCount; ++i) {
-        ID3D12Resource* resource = nullptr;
-        m_swapChain->GetBuffer(i, IID_PPV_ARGS(&resource));
-        m_backBuffers[i].InitializeFromExisting(resource, false);
-    }
-
-    return true;
+    return RefreshBackBuffers();
 }
 
 bool D3D12SwapChain::Initialize(IDXGISwapChain* swapChain, uint32_t width, uint32_t height) {
@@ -59,21 +52,25 @@ bool D3D12SwapChain::Initialize(IDXGISwapChain* swapChain, uint32_t width, uint3
         return false;
     }
 
-    m_width = width;
-    m_height = height;
-
-    m_backBuffers.resize(m_bufferCount);
-    for (uint32_t i = 0; i < m_bufferCount; ++i) {
-        ID3D12Resource* resource = nullptr;
-        m_swapChain->GetBuffer(i, IID_PPV_ARGS(&resource));
-        m_backBuffers[i].InitializeFromExisting(resource, false);
+    DXGI_SWAP_CHAIN_DESC desc = {};
+    hResult = m_swapChain->GetDesc(&desc);
+    if (FAILED(hResult) || desc.BufferCount == 0) {
+        return false;
     }
 
-    return true;
+    m_width = width;
+    m_height = height;
+    m_bufferCount = desc.BufferCount;
+
+    return RefreshBackBuffers();
 }
 
 void D3D12SwapChain::Shutdown() {
+    ReleaseBackBuffers();
+    m_commandQueue.Reset();
     m_swapChain.Reset();
+    m_width = 0;
+    m_height = 0;
 }
 
 uint32_t D3D12SwapChain::GetCurrentBackBufferIndex() const {
@@ -95,9 +92,16 @@ void D3D12SwapChain::Present(uint32_t syncInterval, uint32_t flags) {
 }
 
 void D3D12SwapChain::Resize(uint32_t width, uint32_t height) {
-    m_swapChain->ResizeBuffers(m_bufferCount, width, height, DXGI_FORMAT_R8G8B8A8_UNORM, 0);
+    ReleaseBackBuffers();
+
+    const HRESULT hResult = m_swapChain->ResizeBuffers(m_bufferCount, width, height, DXGI_FORMAT_R8G8B8A8_UNORM, 0);
+    if (FAILED(hResult)) {
+        return;
+    }
+
     m_width = width;
     m_height = height;
+    RefreshBackBuffers();
 }
 
 void* D3D12SwapChain::GetNativeHandle() {
@@ -108,5 +112,34 @@ RHITexture* D3D12SwapChain::GetCurrentBackBuffer() {
     return &GetBackBuffer(GetCurrentBackBufferIndex());
 }
 
+bool D3D12SwapChain::RefreshBackBuffers() {
+    if (!m_swapChain || m_bufferCount == 0) {
+        return false;
+    }
+
+    m_backBuffers.clear();
+    m_backBuffers.resize(m_bufferCount);
+
+    for (uint32_t i = 0; i < m_bufferCount; ++i) {
+        ComPtr<ID3D12Resource> resource;
+        const HRESULT hResult = m_swapChain->GetBuffer(i, IID_PPV_ARGS(&resource));
+        if (FAILED(hResult) || resource == nullptr) {
+            ReleaseBackBuffers();
+            return false;
+        }
+
+        m_backBuffers[i].InitializeFromExisting(resource.Get(), false);
+    }
+
+    return true;
+}
+
+void D3D12SwapChain::ReleaseBackBuffers() {
+    for (D3D12Texture& backBuffer : m_backBuffers) {
+        backBuffer.Shutdown();
+    }
+    m_backBuffers.clear();
+}
+
 } // namespace RHI
 } // namespace XCEngine

tests/RHI/D3D12/unit/test_swap_chain.cpp

@@ -175,6 +175,30 @@ TEST_F(SwapChainTestFixture, SwapChain_Present_DoesNotCrash) {
     ASSERT_NO_FATAL_FAILURE(mSwapChain.Present(0, 0));
 }
 
+TEST_F(SwapChainTestFixture, SwapChain_Resize_RecreatesBackBuffers) {
+    ASSERT_TRUE(mSwapChain.Initialize(
+        mFactory.Get(),
+        mCommandQueue.Get(),
+        mHWND,
+        800,
+        600,
+        2
+    ));
+
+    ID3D12Resource* beforeResize = mSwapChain.GetBackBuffer(0).GetResource();
+    ASSERT_NE(beforeResize, nullptr);
+    EXPECT_EQ(mSwapChain.GetBackBuffer(0).GetWidth(), 800u);
+    EXPECT_EQ(mSwapChain.GetBackBuffer(0).GetHeight(), 600u);
+
+    ASSERT_NO_FATAL_FAILURE(mSwapChain.Resize(1024, 768));
+
+    ID3D12Resource* afterResize = mSwapChain.GetBackBuffer(0).GetResource();
+    ASSERT_NE(afterResize, nullptr);
+    EXPECT_EQ(mSwapChain.GetBackBuffer(0).GetWidth(), 1024u);
+    EXPECT_EQ(mSwapChain.GetBackBuffer(0).GetHeight(), 768u);
+    EXPECT_NE(beforeResize, afterResize);
+}
+
 TEST_F(SwapChainTestFixture, SwapChain_Shutdown_Cleanup) {
     ASSERT_TRUE(mSwapChain.Initialize(
         mFactory.Get(),