yaze/docs/internal/archive/handoffs/handoff-duplicate-rendering-investigation.md

Handoff: Duplicate Element Rendering in Editor Cards

Date: 2025-11-25 Status: In Progress - Diagnostic Added Issue: All elements inside editor cards appear twice (visually stacked)

Problem Description

User reported that elements inside editor cards are "appearing twice on top of one another" - affecting all editors, not specific cards. This suggests a systematic issue with how card content is rendered.

Investigation Summary

Files Examined

File	Issue Checked	Result
proposal_drawer.cc	Duplicate Draw()/DrawContent()	Draw() is dead code - never called
tile16_editor.cc	Missing EndChild()	Begin/End counts balanced
overworld_editor.cc	Orphaned EndChild()	Begin/End counts balanced
editor_card_registry.cc	Dual rendering paths	Mutual exclusion via IsTreeViewMode()
editor_manager.cc	Double Update() calls	Only one editor->Update() per frame
controller.cc	Main loop issues	Single NewFrame()/Update()/Render() cycle
editor_layout.cc	EditorCard Begin/End	Proper ImGui pairing

What Was Ruled Out

1. ProposalDrawer - The Draw() method (lines 75-107) is never called. Only DrawContent() is used via right_panel_manager.cc:238

2. ImGui Begin/End Mismatches - Verified counts in:

   • tile16_editor.cc: 6 BeginChild, 6 EndChild
   • overworld_editor.cc: Balanced pairs with proper End() after each Begin()

3. EditorCardRegistry Double Rendering - DrawSidebar() and DrawTreeSidebar() use different window names (##EditorCardSidebar vs ##TreeSidebar) and are mutually exclusive

4. Multiple Update() Calls - EditorManager::Update() only calls editor->Update() once per frame for each active editor (line 1047)

5. Main Loop Issues - controller.cc has clean frame lifecycle:

   • Line 63-65: Single NewFrame() calls
   • Line 124: Single editor_manager_.Update()
   • Line 134: Single ImGui::Render()

6. Multi-Viewport - ImGuiConfigFlags_ViewportsEnable is NOT enabled (only DockingEnable)

Previous Fixes Found

Comments in codebase indicate prior duplicate rendering issues were fixed:

• editor_manager.cc:827: "Removed duplicate direct call - DrawProposalsPanel()"
• editor_manager.cc:1030: "Removed duplicate call to avoid showing welcome screen twice"

Diagnostic Code Added

Added frame-based duplicate detection to EditorCard class:

Files Modified

src/app/gui/app/editor_layout.h (lines 121-135):

// Debug: Reset frame tracking (call once per frame from main loop)
static void ResetFrameTracking();

// Debug: Check if any card was rendered twice this frame
static bool HasDuplicateRendering();
static const std::string& GetDuplicateCardName();

private:
  static int last_frame_count_;
  static std::vector<std::string> cards_begun_this_frame_;
  static bool duplicate_detected_;
  static std::string duplicate_card_name_;

src/app/gui/app/editor_layout.cc (lines 17-23, 263-285):

• Static variable definitions
• Tracking logic in Begin() that:
  • Resets tracking on new frame
  • Checks if card was already begun this frame
  • Logs to stderr: [EditorCard] DUPLICATE DETECTED: 'Card Name' Begin() called twice in frame N

How to Use

1. Build and run the application from terminal
2. If any card's Begin() is called twice in the same frame, stderr will show:

   [EditorCard] DUPLICATE DETECTED: 'Tile16 Selector' Begin() called twice in frame 1234
   

3. Query programmatically:

   if (gui::EditorCard::HasDuplicateRendering()) {
     LOG_ERROR("Duplicate card: %s", gui::EditorCard::GetDuplicateCardName().c_str());
   }
   

Next Steps

1. Run with diagnostic - Build succeeds, run app and check stderr for duplicate messages

2. If duplicates detected - The log will identify which card(s) are being rendered twice, then trace back to find the double call site

3. If no duplicates detected - The issue may be:

   • ImGui draw list being submitted twice
   • Z-ordering/layering visual artifacts
   • Something outside EditorCard (raw ImGui::Begin calls)

4. Alternative debugging:

   • Enable ImGui Demo Window's "Metrics" to inspect draw calls
   • Add similar tracking to raw ImGui::Begin() calls
   • Check for duplicate textures being drawn at same position

Build Status

Build was in progress when handoff created. Command:

cmake --build build --target yaze -j4

Related Files

• Plan file: ~/.claude/plans/nested-crafting-origami.md
• Editor layout: src/app/gui/app/editor_layout.h, editor_layout.cc
• Main editors: src/app/editor/overworld/overworld_editor.cc
• Card registry: src/app/editor/system/editor_card_registry.cc