openDecal/CLAUDE.md

OpenDecal - Project Context

What This Is

Open-source rebuild of Decal, the plugin framework for Asheron's Call. The original v2.9.8.3 is closed-source. This project produces a fully open-source drop-in replacement with identical COM interfaces and GUIDs for plugin compatibility.

Current Status: All 5 Phases Complete (Skeleton)

The solution compiles with 25 C# projects, 0 errors. Most COM server methods are stubs that need real implementations. See docs/PLAN.md for the full plan.

What's built:

• Phase 1: 14 decompiled .NET projects (Interop.*, Adapter, FileService, DecalUtil)
• Phase 2: 10 native DLLs rewritten as C# COM servers with matching GUIDs
• Phase 3: C++ shims — Inject.DLL (D3D9 hooking) + LauncherHook.DLL
• Phase 4: DenAgent WinForms tray app replacing the MFC original
• Phase 5: WiX installer + build script

What's next (Phase 6):

Bottom-up verification — swap one original DLL at a time with our C# version, test against a running AC client, fix what breaks. See docs/PLAN.md "Phase 6".

Key Files

• Managed/Decal.sln — Main solution (25 projects)
• Managed/Directory.Build.props — Shared build settings (net472, x86)
• Managed/Decal.Interop.*/ — COM interface contracts (the spec for everything)
• Native/InjectModern/ — Inject.DLL C++ source (~530 lines)
• Native/LauncherHookModern/ — LauncherHook.DLL C++ source (~330 lines)
• Native/ — Old C++ source (reference for algorithms, NOT part of the build)
• Installer/Package.wxs — WiX v5 MSI package
• build.cmd — Top-level build script
• docs/PLAN.md — Full project plan with all phases and next steps

Build Commands

# Managed (.NET) — works on Linux/WSL or Windows
dotnet build Managed/Decal.sln

# Native C++ — Windows only, requires VS 2022
cd Native
cmake -G "Visual Studio 17 2022" -A Win32 -B build
cmake --build build --config Release

Architecture

• 10 COM servers (C#): DecalDat, DHS, SpellFilter, DecalInput, DecalNet, DecalFilters, Decal.Core, DecalControls, DecalRender, D3DService
• 2 native DLLs (C++): Inject.DLL (D3D9 vtable hooking), LauncherHook.DLL
• 1 tray app (C# WinForms): DenAgent
• All COM servers use [ComVisible], [Guid], [ClassInterface], [ProgId]
• Original CLSIDs preserved exactly for plugin compatibility

Common Pitfalls

• record types need IsExternalInit — unavailable in net472, use class instead
• CollectionsMarshal.AsSpan unavailable in net472
• LongValueKey enum: correct names are keyStackCount, keyContainer
• tagPOINT defined in Interop.Inject, needed by Interop.Render → add ProjectReference
• ICommandEvents delegates ambiguous between Interop.Controls and Interop.Inject → use using aliases

Goal

Pixel-perfect drop-in replacement for closed-source Decal v2.9.8.3, targeting the original AC client.exe. Existing community plugins (VTank, Mag-Tools, etc.) should load and work without modification.