feat(gameclient): Introduce imgui framework

[jurassicLizard]

Note : to test this please configure in Debug mode before building with -A Win32 -DRTS_BUILD_OPTION_DEBUG=ON -DRTS_BUILD_OPTION_IMGUI=On

all the code is gated behind a RTS_IMGUI_ENABLED perprocessor define for debugging purposes

• What it does : Integrates the Dear Imgui framework and loads a console and demo window overlay
  in debug mode

• What is missing

  • Some useful command or Ideas what it should look like : this PR will just focus on build and runtime integration via ImGui Demo
  • Currently it is permanently enabled when the game is builtwith the imgui option on Gated behind RTS_BUILD_OPTION_IMGUI
  • Code cleanup and SuperHackers Comments etc... done
  • Backporting to Generals done

[greptile-apps]

Greptile Summary

Integrates Dear ImGui framework for debug overlays in both Generals and Zero Hour, gated behind RTS_BUILD_OPTION_IMGUI and restricted to Debug builds. The implementation includes a custom DX8 backend since ImGui doesn't officially support DirectX 8.

Key changes:

• Custom DX8 renderer backend (imgui_impl_dx8.cpp) based on community implementation
• CMake integration that fetches ImGui from GitHub and enforces Debug-only builds
• Proper integration into game loop: input handling in WndProc, frame lifecycle in GameClient, rendering in DX8Wrapper
• Device reset handling with proper invalidation/recreation of ImGui resources
• Comprehensive comments documenting the integration workflow

Previous issues addressed:

• Redundant ImGui::Render() calls have been removed
• Typo "moore" has been fixed
• Null pointer checks added for GetDepthStencilSurface() return values
• Error handling improved for buffer lock operations

Minor style observations:

• Some uses of NULL instead of nullptr remain in imgui_impl_dx8.cpp (lines 72, 184, 311, 340) per custom rule c69cf1a9

Confidence Score: 4/5

• Safe to merge with minor style inconsistencies
• The integration is well-architected with proper lifecycle management and error handling. Previous critical issues (redundant render calls, nullptr derefs) have been fixed. Only minor style issues remain with NULL vs nullptr usage.
• Core/Libraries/Source/ImGui/dx8_backend/imgui_impl_dx8.cpp has style inconsistencies with NULL vs nullptr

Important Files Changed

Filename	Overview
Core/Libraries/Source/ImGui/dx8_backend/imgui_impl_dx8.cpp	Custom DX8 backend implementation for ImGui with proper error handling for depth stencil operations
Core/Libraries/Source/ImGui/CMakeLists.txt	CMake configuration that fetches ImGui and configures the build with debug mode requirement
Generals/Code/GameEngine/Source/GameClient/GameClient.cpp	Integration of ImGui frame lifecycle in game client update loop with proper render calls before early returns
Generals/Code/Libraries/Source/WWVegas/WW3D2/dx8wrapper.cpp	DX8 wrapper handles ImGui context initialization, device reset, and render data output

Sequence Diagram

sequenceDiagram
    participant User
    participant WndProc
    participant GameClient
    participant DX8Wrapper
    participant ImGui
    participant DX8Device

    Note over User,DX8Device: Initialization (Create_Device)
    DX8Wrapper->>ImGui: CreateContext()
    DX8Wrapper->>ImGui: ImGui_ImplWin32_Init(hwnd)
    DX8Wrapper->>ImGui: ImGui_ImplDX8_Init(device)
    ImGui->>DX8Device: AddRef()

    Note over User,DX8Device: Frame Loop
    User->>WndProc: Input Events
    WndProc->>ImGui: ImGui_ImplWin32_WndProcHandler()
    
    GameClient->>ImGui: ImGui_ImplDX8_NewFrame()
    GameClient->>ImGui: ImGui_ImplWin32_NewFrame()
    GameClient->>ImGui: ImGui::NewFrame()
    GameClient->>ImGui: ImGui::ShowDemoWindow()
    GameClient->>ImGui: ImGui::Render()
    
    GameClient->>DX8Wrapper: TheDisplay->DRAW()
    DX8Wrapper->>DX8Device: BeginScene()
    Note over DX8Wrapper: Render game content
    DX8Wrapper->>ImGui: ImGui::GetDrawData()
    DX8Wrapper->>ImGui: ImGui_ImplDX8_RenderDrawData()
    ImGui->>DX8Device: SetRenderState/DrawIndexedPrimitive
    DX8Wrapper->>DX8Device: EndScene()

    Note over User,DX8Device: Device Reset
    DX8Wrapper->>ImGui: ImGui_ImplDX8_InvalidateDeviceObjects()
    DX8Wrapper->>DX8Device: Reset()
    DX8Wrapper->>ImGui: ImGui_ImplDX8_CreateDeviceObjects()

    Note over User,DX8Device: Shutdown
    DX8Wrapper->>ImGui: ImGui_ImplDX8_Shutdown()
    DX8Wrapper->>ImGui: ImGui_ImplWin32_Shutdown()
    DX8Wrapper->>ImGui: DestroyContext()

Loading

[greptile-apps]

_{14 files reviewed, 4 comments}

_{Edit Code Review Agent Settings | Greptile}

[greptile-apps]

Greptile found no issues!

From now on, if a review finishes and we haven't found any issues, we will not post anything, but you can confirm that we reviewed your changes in the status check section.

_{This feature can be toggled off in your Code Review Settings by deselecting "Create a status check for each PR".}

[jurassicLizard]

@greptileai

[jurassicLizard]

relates to : #387 and #2084 (comment)

[greptile-apps]

_{14 files reviewed, 1 comment}

_{Edit Code Review Agent Settings | Greptile}

[greptile-apps]

_{14 files reviewed, 4 comments}

_{Edit Code Review Agent Settings | Greptile}

[jurassicLizard]

@greptileai

[greptile-apps]

_{14 files reviewed, 3 comments}

_{Edit Code Review Agent Settings | Greptile}