Backends: DX12: tidying up, added a ImGui_ImplDX12_Texture helper struct.

Ref 7708

backends/imgui_impl_dx12.cpp

@@ -6,6 +6,9 @@
 //  [X] Renderer: Large meshes support (64k+ vertices) with 16-bit indices.
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
 
+// The aim of imgui_impl_dx12.h/.cpp is to be usable in your engine without any modification.
+// IF YOU FEEL YOU NEED TO MAKE ANY CHANGE TO THIS CODE, please share them and your feedback at https://github.com/ocornut/imgui/
+
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
 // Learn about Dear ImGui:
@@ -16,6 +19,8 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2024-11-15: DirectX12: *BREAKING CHANGE* Changed ImGui_ImplDX12_Init() signature to take a ImGui_ImplDX12_InitInfo struct. Legacy ImGui_ImplDX12_Init() signature is still supported (will obsolete).
+//  2024-11-15: DirectX12: *BREAKING CHANGE* User is now required to pass function pointers to allocate/free SRV Descriptors. We provide convenience legacy fields to pass a single descriptor, matching the old API, but upcoming features will want multiple.
 //  2024-10-23: DirectX12: Unmap() call specify written range. The range is informational and may be used by debug tools.
 //  2024-10-07: DirectX12: Changed default texture sampler to Clamp instead of Repeat/Wrap.
 //  2024-10-07: DirectX12: Expose selected render state in ImGui_ImplDX12_RenderState, which you can access in 'void* platform_io.Renderer_RenderState' during draw callbacks.
@@ -50,17 +55,24 @@
 #pragma comment(lib, "d3dcompiler") // Automatically link with d3dcompiler.lib as we are using D3DCompile() below.
 #endif
 
-// DirectX data
+// DirectX12 data
 struct ImGui_ImplDX12_RenderBuffers;
+
+struct ImGui_ImplDX12_Texture
+{
+    ID3D12Resource*             pTextureResource;
+    D3D12_CPU_DESCRIPTOR_HANDLE hFontSrvCpuDescHandle;
+    D3D12_GPU_DESCRIPTOR_HANDLE hFontSrvGpuDescHandle;
+};
+
 struct ImGui_ImplDX12_Data
 {
+    ImGui_ImplDX12_InitInfo     InitInfo;
     ID3D12Device*               pd3dDevice;
     ID3D12RootSignature*        pRootSignature;
     ID3D12PipelineState*        pPipelineState;
     DXGI_FORMAT                 RTVFormat;
-    ID3D12Resource*             pFontTextureResource;
-    D3D12_CPU_DESCRIPTOR_HANDLE hFontSrvCpuDescHandle;
-    D3D12_GPU_DESCRIPTOR_HANDLE hFontSrvGpuDescHandle;
+    ImGui_ImplDX12_Texture      FontTexture;
     ID3D12DescriptorHeap*       pd3dSrvDescHeap;
     UINT                        numFramesInFlight;
 
@@ -310,6 +322,7 @@ static void ImGui_ImplDX12_CreateFontsTexture()
     io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);
 
     // Upload texture to graphics system
+    ImGui_ImplDX12_Texture* font_tex = &bd->FontTexture;
     {
         D3D12_HEAP_PROPERTIES props;
         memset(&props, 0, sizeof(D3D12_HEAP_PROPERTIES));
@@ -440,13 +453,13 @@ static void ImGui_ImplDX12_CreateFontsTexture()
         srvDesc.Texture2D.MipLevels = desc.MipLevels;
         srvDesc.Texture2D.MostDetailedMip = 0;
         srvDesc.Shader4ComponentMapping = D3D12_DEFAULT_SHADER_4_COMPONENT_MAPPING;
-        bd->pd3dDevice->CreateShaderResourceView(pTexture, &srvDesc, bd->hFontSrvCpuDescHandle);
-        SafeRelease(bd->pFontTextureResource);
-        bd->pFontTextureResource = pTexture;
+        bd->pd3dDevice->CreateShaderResourceView(pTexture, &srvDesc, font_tex->hFontSrvCpuDescHandle);
+        SafeRelease(font_tex->pTextureResource);
+        font_tex->pTextureResource = pTexture;
     }
 
     // Store our identifier
-    io.Fonts->SetTexID((ImTextureID)bd->hFontSrvGpuDescHandle.ptr);
+    io.Fonts->SetTexID((ImTextureID)font_tex->hFontSrvGpuDescHandle.ptr);
 }
 
 bool    ImGui_ImplDX12_CreateDeviceObjects()
@@ -692,8 +705,15 @@ void    ImGui_ImplDX12_InvalidateDeviceObjects()
     ImGuiIO& io = ImGui::GetIO();
     SafeRelease(bd->pRootSignature);
     SafeRelease(bd->pPipelineState);
-    SafeRelease(bd->pFontTextureResource);
-    io.Fonts->SetTexID(0); // We copied bd->pFontTextureView to io.Fonts->TexID so let's clear that as well.
+
+    // Free SRV descriptor used by texture
+    ImGui_ImplDX12_Texture* font_tex = &bd->FontTexture;
+#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
+    if (bd->InitInfo.SrvDescriptorFreeFn != NULL)
+#endif
+        bd->InitInfo.SrvDescriptorFreeFn(&bd->InitInfo, font_tex->hFontSrvCpuDescHandle, font_tex->hFontSrvGpuDescHandle);
+    SafeRelease(font_tex->pTextureResource);
+    io.Fonts->SetTexID(0); // We copied bd->hFontSrvGpuDescHandle to io.Fonts->TexID so let's clear that as well.
 
     for (UINT i = 0; i < bd->numFramesInFlight; i++)
     {
@@ -703,8 +723,7 @@ void    ImGui_ImplDX12_InvalidateDeviceObjects()
     }
 }
 
-bool ImGui_ImplDX12_Init(ID3D12Device* device, int num_frames_in_flight, DXGI_FORMAT rtv_format, ID3D12DescriptorHeap* cbv_srv_heap,
-                         D3D12_CPU_DESCRIPTOR_HANDLE font_srv_cpu_desc_handle, D3D12_GPU_DESCRIPTOR_HANDLE font_srv_gpu_desc_handle)
+bool ImGui_ImplDX12_Init(ImGui_ImplDX12_InitInfo* init_info)
 {
     ImGuiIO& io = ImGui::GetIO();
     IMGUI_CHECKVERSION();
@@ -712,21 +731,39 @@ bool ImGui_ImplDX12_Init(ID3D12Device* device, int num_frames_in_flight, DXGI_FO
 
     // Setup backend capabilities flags
     ImGui_ImplDX12_Data* bd = IM_NEW(ImGui_ImplDX12_Data)();
+
+    bd->InitInfo = *init_info; // Deep copy
+    bd->pd3dDevice = init_info->Device;
+    bd->RTVFormat = init_info->RTVFormat;
+    bd->numFramesInFlight = init_info->NumFramesInFlight;
+    bd->pd3dSrvDescHeap = init_info->SrvDescriptorHeap;
+
     io.BackendRendererUserData = (void*)bd;
     io.BackendRendererName = "imgui_impl_dx12";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
 
-    bd->pd3dDevice = device;
-    bd->RTVFormat = rtv_format;
-    bd->hFontSrvCpuDescHandle = font_srv_cpu_desc_handle;
-    bd->hFontSrvGpuDescHandle = font_srv_gpu_desc_handle;
-    bd->pFrameResources = new ImGui_ImplDX12_RenderBuffers[num_frames_in_flight];
-    bd->numFramesInFlight = num_frames_in_flight;
-    bd->pd3dSrvDescHeap = cbv_srv_heap;
-    bd->frameIndex = UINT_MAX;
+    // Allocate 1 SRV descriptor for the font texture
+    if (init_info->SrvDescriptorAllocFn != NULL)
+    {
+        IM_ASSERT(init_info->SrvDescriptorFreeFn != NULL);
+        init_info->SrvDescriptorAllocFn(&bd->InitInfo, &bd->FontTexture.hFontSrvCpuDescHandle, &bd->FontTexture.hFontSrvGpuDescHandle);
+    }
+    else
+    {
+#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
+        IM_ASSERT(init_info->LegacySingleSrvCpuDescriptor.ptr != 0 && init_info->LegacySingleSrvGpuDescriptor.ptr != 0);
+        bd->FontTexture.hFontSrvCpuDescHandle = init_info->LegacySingleSrvCpuDescriptor;
+        bd->FontTexture.hFontSrvGpuDescHandle = init_info->LegacySingleSrvGpuDescriptor;
+#else
+        IM_ASSERT(init_info->SrvDescriptorAllocFn != NULL);
+        IM_ASSERT(init_info->SrvDescriptorFreeFn != NULL);
+#endif
+    }
 
     // Create buffers with a default size (they will later be grown as needed)
-    for (int i = 0; i < num_frames_in_flight; i++)
+    bd->frameIndex = UINT_MAX;
+    bd->pFrameResources = new ImGui_ImplDX12_RenderBuffers[bd->numFramesInFlight];
+    for (int i = 0; i < (int)bd->numFramesInFlight; i++)
     {
         ImGui_ImplDX12_RenderBuffers* fr = &bd->pFrameResources[i];
         fr->IndexBuffer = nullptr;
@@ -738,6 +775,22 @@ bool ImGui_ImplDX12_Init(ID3D12Device* device, int num_frames_in_flight, DXGI_FO
     return true;
 }
 
+#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
+// Legacy initialization API Obsoleted in 1.91.5
+// font_srv_cpu_desc_handle and font_srv_gpu_desc_handle are handles to a single SRV descriptor to use for the internal font texture, they must be in 'srv_descriptor_heap'
+bool ImGui_ImplDX12_Init(ID3D12Device* device, int num_frames_in_flight, DXGI_FORMAT rtv_format, ID3D12DescriptorHeap* srv_descriptor_heap, D3D12_CPU_DESCRIPTOR_HANDLE font_srv_cpu_desc_handle, D3D12_GPU_DESCRIPTOR_HANDLE font_srv_gpu_desc_handle)
+{
+    ImGui_ImplDX12_InitInfo init_info;
+    init_info.Device = device;
+    init_info.NumFramesInFlight = num_frames_in_flight;
+    init_info.RTVFormat = rtv_format;
+    init_info.SrvDescriptorHeap = srv_descriptor_heap;
+    init_info.LegacySingleSrvCpuDescriptor = font_srv_cpu_desc_handle;
+    init_info.LegacySingleSrvGpuDescriptor = font_srv_gpu_desc_handle;;
+    return ImGui_ImplDX12_Init(&init_info);
+}
+#endif
+
 void ImGui_ImplDX12_Shutdown()
 {
     ImGui_ImplDX12_Data* bd = ImGui_ImplDX12_GetBackendData();
@@ -747,6 +800,7 @@ void ImGui_ImplDX12_Shutdown()
     // Clean up windows and device objects
     ImGui_ImplDX12_InvalidateDeviceObjects();
     delete[] bd->pFrameResources;
+
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
     io.BackendFlags &= ~ImGuiBackendFlags_RendererHasVtxOffset;

backends/imgui_impl_dx12.h

@@ -6,6 +6,9 @@
 //  [X] Renderer: Large meshes support (64k+ vertices) with 16-bit indices.
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
 
+// The aim of imgui_impl_dx12.h/.cpp is to be usable in your engine without any modification.
+// IF YOU FEEL YOU NEED TO MAKE ANY CHANGE TO THIS CODE, please share them and your feedback at https://github.com/ocornut/imgui/
+
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
 // Learn about Dear ImGui:
@@ -18,24 +21,42 @@
 #include "imgui.h"      // IMGUI_IMPL_API
 #ifndef IMGUI_DISABLE
 #include <dxgiformat.h> // DXGI_FORMAT
+#include <d3d12.h>      // D3D12_CPU_DESCRIPTOR_HANDLE
 
-struct ID3D12Device;
-struct ID3D12DescriptorHeap;
-struct ID3D12GraphicsCommandList;
-struct D3D12_CPU_DESCRIPTOR_HANDLE;
-struct D3D12_GPU_DESCRIPTOR_HANDLE;
+// Initialization data, for ImGui_ImplDX12_Init()
+struct ImGui_ImplDX12_InitInfo
+{
+    ID3D12Device*               Device;
+    ID3D12CommandQueue*         CommandQueue;
+    int                         NumFramesInFlight;
+    DXGI_FORMAT                 RTVFormat;
+    void*                       UserData;
+
+    // Allocating SRV descriptors for textures is up to the application, so we provide callbacks.
+    // (current version of the backend will only allocate one descriptor, future versions will need to allocate more)
+    ID3D12DescriptorHeap*       SrvDescriptorHeap;
+    void                        (*SrvDescriptorAllocFn)(ImGui_ImplDX12_InitInfo* info, D3D12_CPU_DESCRIPTOR_HANDLE* out_cpu_desc_handle, D3D12_GPU_DESCRIPTOR_HANDLE* out_gpu_desc_handle);
+    void                        (*SrvDescriptorFreeFn)(ImGui_ImplDX12_InitInfo* info, D3D12_CPU_DESCRIPTOR_HANDLE cpu_desc_handle, D3D12_GPU_DESCRIPTOR_HANDLE gpu_desc_handle);
+#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
+    D3D12_CPU_DESCRIPTOR_HANDLE LegacySingleSrvCpuDescriptor; // To facilitate transition from single descriptor to allocator callback, you may use those.
+    D3D12_GPU_DESCRIPTOR_HANDLE LegacySingleSrvGpuDescriptor;
+#endif
+
+    ImGui_ImplDX12_InitInfo()   { memset(this, 0, sizeof(*this)); }
+};
 
 // Follow "Getting Started" link and check examples/ folder to learn about using backends!
-
-// Before calling the render function, caller must prepare the command list by resetting it and setting the appropriate
-// render target and descriptor heap that contains font_srv_cpu_desc_handle/font_srv_gpu_desc_handle.
-// font_srv_cpu_desc_handle and font_srv_gpu_desc_handle are handles to a single SRV descriptor to use for the internal font texture.
-IMGUI_IMPL_API bool     ImGui_ImplDX12_Init(ID3D12Device* device, int num_frames_in_flight, DXGI_FORMAT rtv_format, ID3D12DescriptorHeap* cbv_srv_heap,
-                                            D3D12_CPU_DESCRIPTOR_HANDLE font_srv_cpu_desc_handle, D3D12_GPU_DESCRIPTOR_HANDLE font_srv_gpu_desc_handle);
+IMGUI_IMPL_API bool     ImGui_ImplDX12_Init(ImGui_ImplDX12_InitInfo* info);
 IMGUI_IMPL_API void     ImGui_ImplDX12_Shutdown();
 IMGUI_IMPL_API void     ImGui_ImplDX12_NewFrame();
 IMGUI_IMPL_API void     ImGui_ImplDX12_RenderDrawData(ImDrawData* draw_data, ID3D12GraphicsCommandList* graphics_command_list);
 
+#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
+// Legacy initialization API Obsoleted in 1.91.5
+// font_srv_cpu_desc_handle and font_srv_gpu_desc_handle are handles to a single SRV descriptor to use for the internal font texture, they must be in 'srv_descriptor_heap'
+IMGUI_IMPL_API bool     ImGui_ImplDX12_Init(ID3D12Device* device, int num_frames_in_flight, DXGI_FORMAT rtv_format, ID3D12DescriptorHeap* srv_descriptor_heap, D3D12_CPU_DESCRIPTOR_HANDLE font_srv_cpu_desc_handle, D3D12_GPU_DESCRIPTOR_HANDLE font_srv_gpu_desc_handle);
+#endif
+
 // Use if you want to reset your rendering device without losing Dear ImGui state.
 IMGUI_IMPL_API bool     ImGui_ImplDX12_CreateDeviceObjects();
 IMGUI_IMPL_API void     ImGui_ImplDX12_InvalidateDeviceObjects();

docs/CHANGELOG.txt

@@ -35,6 +35,28 @@ HOW TO UPDATE?
   and API updates have been a little more frequent lately. They are documented below and in imgui.cpp and should not affect all users.
 - Please report any issue!
 
+-----------------------------------------------------------------------
+ VERSION 1.91.6 WIP (In Progress)
+-----------------------------------------------------------------------
+
+Breaking changes:
+
+- Backends: DX12: Changed ImGui_ImplDX12_Init() signature to take a
+  ImGui_ImplDX12_InitInfo struct.
+  - Using the new API, application is now required to pass function pointers
+    to allocate/free SRV Descriptors.
+  - We provide convenience legacy fields to pass a single descriptor,
+    matching the old API, but upcoming features will want multiple.
+  - Legacy ImGui_ImplDX12_Init() signature is still supported (will obsolete).
+
+Other changes:
+
+- Error Handling: fixed cases where recoverable error handling would crash when 
+  processing errors outside of the NewFrame()..EndFrame() scope. (#1651)
+- Examples: Win32+DX12: Using a basic free-list allocator to manage multiple
+  SRV descriptors.
+
+
 -----------------------------------------------------------------------
  VERSION 1.91.5 (Released 2024-11-07)
 -----------------------------------------------------------------------
@@ -64,6 +86,11 @@ Other changes:
   between _Header and _HeaderHovered which was introduced v1.91 (#8106, #1861)
 - Buttons: using ImGuiItemFlags_ButtonRepeat makes default button behavior use
   PressedOnClick instead of PressedOnClickRelease when unspecified.
+  - This is intended to make the +/- buttons of InputInt/InputFloat react on the
+    initial mouse down event.
+  - Note that it may reveal incorrect usage if you were using InputInt/InputFloat
+    without persistent storage by relying solely on e.g. IsItemDeactivatedAfterEdit():
+    this was never supported and didn't work consistantly (see #8149).
 - InputText: fixed a bug (regression in 1.91.2) where modifying text buffer within
   a callback would sometimes prevents further appending to the buffer.
 - Tabs, Style: made ImGuiCol_TabDimmedSelectedOverline alpha 0 (not visible) in default
@@ -86,6 +113,7 @@ Other changes:
 - Examples: Android+OpenGL: Using ALooper_pollOnce() instead of ALooper_pollAll()
   which has been deprecated. (#8013) [@feather179]
 
+
 -----------------------------------------------------------------------
  VERSION 1.91.4 (Released 2024-10-18)
 -----------------------------------------------------------------------

examples/example_win32_directx12/main.cpp

@@ -22,23 +22,70 @@
 #pragma comment(lib, "dxguid.lib")
 #endif
 
-#include "imgui_internal.h"
+// Config for example app
+static const int APP_NUM_FRAMES_IN_FLIGHT = 3;
+static const int APP_NUM_BACK_BUFFERS = 3;
+static const int APP_SRV_HEAP_SIZE = 64;
 
 struct FrameContext
 {
-    ID3D12CommandAllocator* CommandAllocator;
-    UINT64                  FenceValue;
+    ID3D12CommandAllocator*     CommandAllocator;
+    UINT64                      FenceValue;
+};
+
+// Simple free list based allocator
+struct ExampleDescriptorHeapAllocator
+{
+    ID3D12DescriptorHeap*       Heap = nullptr;
+    D3D12_DESCRIPTOR_HEAP_TYPE  HeapType = D3D12_DESCRIPTOR_HEAP_TYPE_NUM_TYPES;
+    D3D12_CPU_DESCRIPTOR_HANDLE HeapStartCpu;
+    D3D12_GPU_DESCRIPTOR_HANDLE HeapStartGpu;
+    UINT                        HeapHandleIncrement;
+    ImVector<int>               FreeIndices;
+
+    void Create(ID3D12Device* device, ID3D12DescriptorHeap* heap)
+    {
+        IM_ASSERT(Heap == nullptr && FreeIndices.empty());
+        Heap = heap;
+        D3D12_DESCRIPTOR_HEAP_DESC desc = heap->GetDesc();
+        HeapType = desc.Type;
+        HeapStartCpu = Heap->GetCPUDescriptorHandleForHeapStart();
+        HeapStartGpu = Heap->GetGPUDescriptorHandleForHeapStart();
+        HeapHandleIncrement = device->GetDescriptorHandleIncrementSize(HeapType);
+        FreeIndices.reserve((int)desc.NumDescriptors);
+        for (int n = desc.NumDescriptors; n > 0; n--)
+            FreeIndices.push_back(n);
+    }
+    void Destroy()
+    {
+        Heap = NULL;
+        FreeIndices.clear();
+    }
+    void Alloc(D3D12_CPU_DESCRIPTOR_HANDLE* out_cpu_desc_handle, D3D12_GPU_DESCRIPTOR_HANDLE* out_gpu_desc_handle)
+    {
+        IM_ASSERT(FreeIndices.Size > 0);
+        int idx = FreeIndices.back();
+        FreeIndices.pop_back();
+        out_cpu_desc_handle->ptr = HeapStartCpu.ptr + (idx * HeapHandleIncrement);
+        out_gpu_desc_handle->ptr = HeapStartGpu.ptr + (idx * HeapHandleIncrement);
+    }
+    void Free(D3D12_CPU_DESCRIPTOR_HANDLE out_cpu_desc_handle, D3D12_GPU_DESCRIPTOR_HANDLE out_gpu_desc_handle)
+    {
+        int cpu_idx = (int)((out_cpu_desc_handle.ptr - HeapStartCpu.ptr) / HeapHandleIncrement);
+        int gpu_idx = (int)((out_gpu_desc_handle.ptr - HeapStartGpu.ptr) / HeapHandleIncrement);
+        IM_ASSERT(cpu_idx == gpu_idx);
+        FreeIndices.push_back(cpu_idx);
+    }
 };
 
 // Data
-static int const                    NUM_FRAMES_IN_FLIGHT = 3;
-static FrameContext                 g_frameContext[NUM_FRAMES_IN_FLIGHT] = {};
+static FrameContext                 g_frameContext[APP_NUM_FRAMES_IN_FLIGHT] = {};
 static UINT                         g_frameIndex = 0;
 
-static int const                    NUM_BACK_BUFFERS = 3;
 static ID3D12Device*                g_pd3dDevice = nullptr;
 static ID3D12DescriptorHeap*        g_pd3dRtvDescHeap = nullptr;
 static ID3D12DescriptorHeap*        g_pd3dSrvDescHeap = nullptr;
+static ExampleDescriptorHeapAllocator g_pd3dSrvDescHeapAlloc;
 static ID3D12CommandQueue*          g_pd3dCommandQueue = nullptr;
 static ID3D12GraphicsCommandList*   g_pd3dCommandList = nullptr;
 static ID3D12Fence*                 g_fence = nullptr;
@@ -47,8 +94,8 @@ static UINT64                       g_fenceLastSignaledValue = 0;
 static IDXGISwapChain3*             g_pSwapChain = nullptr;
 static bool                         g_SwapChainOccluded = false;
 static HANDLE                       g_hSwapChainWaitableObject = nullptr;
-static ID3D12Resource*              g_mainRenderTargetResource[NUM_BACK_BUFFERS] = {};
-static D3D12_CPU_DESCRIPTOR_HANDLE  g_mainRenderTargetDescriptor[NUM_BACK_BUFFERS] = {};
+static ID3D12Resource*              g_mainRenderTargetResource[APP_NUM_BACK_BUFFERS] = {};
+static D3D12_CPU_DESCRIPTOR_HANDLE  g_mainRenderTargetDescriptor[APP_NUM_BACK_BUFFERS] = {};
 
 // Forward declarations of helper functions
 bool CreateDeviceD3D(HWND hWnd);
@@ -93,10 +140,18 @@ int main(int, char**)
 
     // Setup Platform/Renderer backends
     ImGui_ImplWin32_Init(hwnd);
-    ImGui_ImplDX12_Init(g_pd3dDevice, NUM_FRAMES_IN_FLIGHT,
-        DXGI_FORMAT_R8G8B8A8_UNORM, g_pd3dSrvDescHeap,
-        g_pd3dSrvDescHeap->GetCPUDescriptorHandleForHeapStart(),
-        g_pd3dSrvDescHeap->GetGPUDescriptorHandleForHeapStart());
+
+    ImGui_ImplDX12_InitInfo init_info = {};
+    init_info.Device = g_pd3dDevice;
+    init_info.CommandQueue = g_pd3dCommandQueue;
+    init_info.NumFramesInFlight = APP_NUM_FRAMES_IN_FLIGHT;
+    init_info.RTVFormat = DXGI_FORMAT_R8G8B8A8_UNORM;
+    // Allocating SRV descriptors (for textures) is up to the application, so we provide callbacks.
+    // (current version of the backend will only allocate one descriptor, future versions will need to allocate more)
+    init_info.SrvDescriptorHeap = g_pd3dSrvDescHeap;
+    init_info.SrvDescriptorAllocFn = [](ImGui_ImplDX12_InitInfo*, D3D12_CPU_DESCRIPTOR_HANDLE* out_cpu_handle, D3D12_GPU_DESCRIPTOR_HANDLE* out_gpu_handle) { return g_pd3dSrvDescHeapAlloc.Alloc(out_cpu_handle, out_gpu_handle); };
+    init_info.SrvDescriptorFreeFn = [](ImGui_ImplDX12_InitInfo*, D3D12_CPU_DESCRIPTOR_HANDLE cpu_handle, D3D12_GPU_DESCRIPTOR_HANDLE gpu_handle)            { return g_pd3dSrvDescHeapAlloc.Free(cpu_handle, gpu_handle); };
+    ImGui_ImplDX12_Init(&init_info);
 
     // Load Fonts
     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them.
@@ -249,7 +304,7 @@ bool CreateDeviceD3D(HWND hWnd)
     DXGI_SWAP_CHAIN_DESC1 sd;
     {
         ZeroMemory(&sd, sizeof(sd));
-        sd.BufferCount = NUM_BACK_BUFFERS;
+        sd.BufferCount = APP_NUM_BACK_BUFFERS;
         sd.Width = 0;
         sd.Height = 0;
         sd.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
@@ -292,7 +347,7 @@ bool CreateDeviceD3D(HWND hWnd)
     {
         D3D12_DESCRIPTOR_HEAP_DESC desc = {};
         desc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_RTV;
-        desc.NumDescriptors = NUM_BACK_BUFFERS;
+        desc.NumDescriptors = APP_NUM_BACK_BUFFERS;
         desc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_NONE;
         desc.NodeMask = 1;
         if (g_pd3dDevice->CreateDescriptorHeap(&desc, IID_PPV_ARGS(&g_pd3dRtvDescHeap)) != S_OK)
@@ -300,7 +355,7 @@ bool CreateDeviceD3D(HWND hWnd)
 
         SIZE_T rtvDescriptorSize = g_pd3dDevice->GetDescriptorHandleIncrementSize(D3D12_DESCRIPTOR_HEAP_TYPE_RTV);
         D3D12_CPU_DESCRIPTOR_HANDLE rtvHandle = g_pd3dRtvDescHeap->GetCPUDescriptorHandleForHeapStart();
-        for (UINT i = 0; i < NUM_BACK_BUFFERS; i++)
+        for (UINT i = 0; i < APP_NUM_BACK_BUFFERS; i++)
         {
             g_mainRenderTargetDescriptor[i] = rtvHandle;
             rtvHandle.ptr += rtvDescriptorSize;
@@ -310,10 +365,11 @@ bool CreateDeviceD3D(HWND hWnd)
     {
         D3D12_DESCRIPTOR_HEAP_DESC desc = {};
         desc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_CBV_SRV_UAV;
-        desc.NumDescriptors = 1;
+        desc.NumDescriptors = APP_SRV_HEAP_SIZE;
         desc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_SHADER_VISIBLE;
         if (g_pd3dDevice->CreateDescriptorHeap(&desc, IID_PPV_ARGS(&g_pd3dSrvDescHeap)) != S_OK)
             return false;
+        g_pd3dSrvDescHeapAlloc.Create(g_pd3dDevice, g_pd3dSrvDescHeap);
     }
 
     {
@@ -325,7 +381,7 @@ bool CreateDeviceD3D(HWND hWnd)
             return false;
     }
 
-    for (UINT i = 0; i < NUM_FRAMES_IN_FLIGHT; i++)
+    for (UINT i = 0; i < APP_NUM_FRAMES_IN_FLIGHT; i++)
         if (g_pd3dDevice->CreateCommandAllocator(D3D12_COMMAND_LIST_TYPE_DIRECT, IID_PPV_ARGS(&g_frameContext[i].CommandAllocator)) != S_OK)
             return false;
 
@@ -351,7 +407,7 @@ bool CreateDeviceD3D(HWND hWnd)
             return false;
         swapChain1->Release();
         dxgiFactory->Release();
-        g_pSwapChain->SetMaximumFrameLatency(NUM_BACK_BUFFERS);
+        g_pSwapChain->SetMaximumFrameLatency(APP_NUM_BACK_BUFFERS);
         g_hSwapChainWaitableObject = g_pSwapChain->GetFrameLatencyWaitableObject();
     }
 
@@ -364,7 +420,7 @@ void CleanupDeviceD3D()
     CleanupRenderTarget();
     if (g_pSwapChain) { g_pSwapChain->SetFullscreenState(false, nullptr); g_pSwapChain->Release(); g_pSwapChain = nullptr; }
     if (g_hSwapChainWaitableObject != nullptr) { CloseHandle(g_hSwapChainWaitableObject); }
-    for (UINT i = 0; i < NUM_FRAMES_IN_FLIGHT; i++)
+    for (UINT i = 0; i < APP_NUM_FRAMES_IN_FLIGHT; i++)
         if (g_frameContext[i].CommandAllocator) { g_frameContext[i].CommandAllocator->Release(); g_frameContext[i].CommandAllocator = nullptr; }
     if (g_pd3dCommandQueue) { g_pd3dCommandQueue->Release(); g_pd3dCommandQueue = nullptr; }
     if (g_pd3dCommandList) { g_pd3dCommandList->Release(); g_pd3dCommandList = nullptr; }
@@ -386,7 +442,7 @@ void CleanupDeviceD3D()
 
 void CreateRenderTarget()
 {
-    for (UINT i = 0; i < NUM_BACK_BUFFERS; i++)
+    for (UINT i = 0; i < APP_NUM_BACK_BUFFERS; i++)
     {
         ID3D12Resource* pBackBuffer = nullptr;
         g_pSwapChain->GetBuffer(i, IID_PPV_ARGS(&pBackBuffer));
@@ -399,13 +455,13 @@ void CleanupRenderTarget()
 {
     WaitForLastSubmittedFrame();
 
-    for (UINT i = 0; i < NUM_BACK_BUFFERS; i++)
+    for (UINT i = 0; i < APP_NUM_BACK_BUFFERS; i++)
         if (g_mainRenderTargetResource[i]) { g_mainRenderTargetResource[i]->Release(); g_mainRenderTargetResource[i] = nullptr; }
 }
 
 void WaitForLastSubmittedFrame()
 {
-    FrameContext* frameCtx = &g_frameContext[g_frameIndex % NUM_FRAMES_IN_FLIGHT];
+    FrameContext* frameCtx = &g_frameContext[g_frameIndex % APP_NUM_FRAMES_IN_FLIGHT];
 
     UINT64 fenceValue = frameCtx->FenceValue;
     if (fenceValue == 0)
@@ -427,7 +483,7 @@ FrameContext* WaitForNextFrameResources()
     HANDLE waitableObjects[] = { g_hSwapChainWaitableObject, nullptr };
     DWORD numWaitableObjects = 1;
 
-    FrameContext* frameCtx = &g_frameContext[nextFrameIndex % NUM_FRAMES_IN_FLIGHT];
+    FrameContext* frameCtx = &g_frameContext[nextFrameIndex % APP_NUM_FRAMES_IN_FLIGHT];
     UINT64 fenceValue = frameCtx->FenceValue;
     if (fenceValue != 0) // means no fence was signaled
     {

imgui.cpp

@@ -1,4 +1,4 @@
-// dear imgui, v1.91.5
+// dear imgui, v1.91.6 WIP
 // (main code and documentation)
 
 // Help:
@@ -5788,7 +5788,7 @@ bool ImGui::IsItemDeactivatedAfterEdit()
     return IsItemDeactivated() && (g.ActiveIdPreviousFrameHasBeenEditedBefore || (g.ActiveId == 0 && g.ActiveIdHasBeenEditedBefore));
 }
 
-// == GetItemID() == GetFocusID()
+// == (GetItemID() == GetFocusID() && GetFocusID() != 0)
 bool ImGui::IsItemFocused()
 {
     ImGuiContext& g = *GImGui;
@@ -10542,7 +10542,7 @@ bool    ImGui::ErrorLog(const char* msg)
     // Output to tooltip
     if (g.IO.ConfigErrorRecoveryEnableTooltip)
     {
-        if (BeginErrorTooltip())
+        if (g.WithinFrameScope && BeginErrorTooltip())
         {
             if (g.ErrorCountCurrentFrame < 20)
             {
@@ -10579,7 +10579,7 @@ void ImGui::ErrorCheckEndFrameFinalizeErrorTooltip()
         BulletText("Code should use PushID()/PopID() in loops, or append \"##xx\" to same-label identifiers!");
         BulletText("Empty label e.g. Button(\"\") == same ID as parent widget/node. Use Button(\"##xx\") instead!");
         //BulletText("Code intending to use duplicate ID may use e.g. PushItemFlag(ImGuiItemFlags_AllowDuplicateId, true); ... PopItemFlag()"); // Not making this too visible for fear of it being abused.
-        BulletText("Set io.ConfigDebugDetectIdConflicts=false to disable this warning in non-programmers builds.");
+        BulletText("Set io.ConfigDebugHighlightIdConflicts=false to disable this warning in non-programmers builds.");
         Separator();
         Text("(Hold CTRL to: use");
         SameLine();

imgui.h

@@ -1,4 +1,4 @@
-// dear imgui, v1.91.5
+// dear imgui, v1.91.6 WIP
 // (headers)
 
 // Help:
@@ -28,8 +28,8 @@
 
 // Library Version
 // (Integer encoded as XYYZZ for use in #if preprocessor conditionals, e.g. '#if IMGUI_VERSION_NUM >= 12345')
-#define IMGUI_VERSION       "1.91.5"
-#define IMGUI_VERSION_NUM   19150
+#define IMGUI_VERSION       "1.91.6 WIP"
+#define IMGUI_VERSION_NUM   19151
 #define IMGUI_HAS_TABLE
 
 /*

imgui_demo.cpp

@@ -1,4 +1,4 @@
-// dear imgui, v1.91.5
+// dear imgui, v1.91.6 WIP
 // (demo code)
 
 // Help:

imgui_draw.cpp

@@ -1,4 +1,4 @@
-// dear imgui, v1.91.5
+// dear imgui, v1.91.6 WIP
 // (drawing and font code)
 
 /*

imgui_internal.h

@@ -1,4 +1,4 @@
-// dear imgui, v1.91.5
+// dear imgui, v1.91.6 WIP
 // (internal structures/api)
 
 // You may use this file to debug, understand or extend Dear ImGui features but we don't provide any guarantee of forward compatibility.

imgui_tables.cpp

@@ -1,4 +1,4 @@
-// dear imgui, v1.91.5
+// dear imgui, v1.91.6 WIP
 // (tables and columns code)
 
 /*

imgui_widgets.cpp

@@ -1,4 +1,4 @@
-// dear imgui, v1.91.5
+// dear imgui, v1.91.6 WIP
 // (widgets code)
 
 /*