Juliet/AgentData/Imgui.md

ImGui Integration & Memory Debugger

Task List

• Preparation

  • Fetch Dear ImGui Source Files (Verified existing submodule)
  • Create External/imgui/Imgui.bff
  • Update fbuild.bff to include Imgui.bff
  • Update Juliet.bff to link ImGui and include paths
  • Update D3D12DescriptorHeap to support ImGui (SRV for Font)

• Memory Arena Debugging

  • Modify MemoryArena struct to store allocation tags (Debug builds only)
  • Update ArenaPush signature to accept const char* tag
  • Update call sites (default parameter should minimize churn)

• ImGui Core & TDD

  • Create Core/ImGui/ImGuiService.h/cpp (Wrapper)
  • Create Core/ImGui/ImGuiTests.cpp
  • Implement ImGui::SetAllocatorFunctions using EngineArena
  • Test context creation and IO setup

• Integration

  • Win32: Integrate WndProc in Win32DisplayEvent.cpp
  • DX12: Initialize/Shutdown in D3D12GraphicsDevice (Implemented in ImGuiRenderer.cpp)
  • DX12: Render Frame in D3D12GraphicsDevice (Fixed Buffer Crash)

• Memory Debugger

  • Create Engine/Debug/MemoryDebugger.h/cpp
  • Implement DrawMemoryArena(const char* name, MemoryArena* arena) with Allocation Tags
  • Implement Hex View for Arena Data (Allocations list implemented, Hex view pending/skipped)
  • Integrate into Main Loop (Toggle with 'Home' key)

• Verification

  • Launch and verify ImGui renders
  • Verify Memory Debugger shows allocations and tags

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Implementation Plan

Goal Description

Integrate Dear ImGui into the Juliet engine. Implement a specialized Test Driven Development (TDD) approach. Create a Memory Debugger panel to visualize MemoryArena state with allocation tags.

Proposed Changes

Build System

[NEW] Imgui.bff

• Defines the ImGui library configuration.
• Includes imgui.cpp, imgui_draw.cpp, imgui_tables.cpp, imgui_widgets.cpp, imgui_demo.cpp.
• Includes backends: imgui_impl_win32.cpp, imgui_impl_dx12.cpp.

[MODIFY] fbuild.bff

• Include External/imgui/Imgui.bff.

[MODIFY] Juliet.bff

• Add ImGui to Juliet library dependencies.
• Add External/imgui and External/imgui/backends to include paths.

Core/Memory

[MODIFY] MemoryArena.h [MODIFY] MemoryArena.cpp

• Struct Change: Add AllocationTracking vector (likely std::vector wrapped or fixed size array) in JULIET_DEBUG.
• Function Change: ArenaPush(..., const char* tag = nullptr).
• Logic: Store offset + tag on push.

Core/ImGui

[NEW] ImGuiService.h [NEW] ImGuiService.cpp

• Wrapper for ImGui lifecycle.
• Uses EngineArena for internal ImGui allocations.

[NEW] ImGuiTests.cpp

• TDD suite for ImGui service.

Graphics/D3D12

[MODIFY] D3D12GraphicsDevice.cpp

• ImGui backend initialization and rendering.

Engine/Debug

[NEW] MemoryDebugger.h [NEW] MemoryDebugger.cpp

• Draw arena usage bar using tracked tags.
• Draw hex dump.