MM2ED Editor

MM2ED Editor

MM2ED — Might & Magic II (Amiga) Data Editor

A Dear ImGui + GLFW + OpenGL3 editor for the reverse-engineered MM2 .dat data files. Structured so that each data type has its own self-contained section (modeled on the GRACE and LorED editors), with a clean split between the data layer (core/) and the UI layer (sections/).

Build

Dependencies (Dear ImGui docking branch, GLFW 3.4, portable-file-dialogs) are fetched automatically by CMake FetchContent — no vendoring required.

cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release
cmake --build build
./build/MM2ED        # MM2ED.exe on Windows

Requires a C++17 compiler, CMake >= 3.16, and internet access on first configure (to clone deps into build/_deps).

Usage

1. File > Open Data Folder... and pick the directory containing the MM2 .dat files (e.g. the workspace root, or MM2BOOT/).
2. Pick a data type in the Data Files panel on the left.
3. Edit in the Editor panel. * = unsaved changes, x = file not found.
4. Ctrl+S saves the active file; File > Save All writes every loaded file.

Project layout

editor/
  CMakeLists.txt          FetchContent deps + glob of src/
  src/
    main.cpp              GLFW/OpenGL3 init + main loop
    app/
      App.{h,cpp}         Dockspace, menu, section registry, save/load, cross-refs
      AppState.h          Shared cross-panel state (data dir, status line)
      Section.h           Abstract base: title/fileName/load/save/draw
    core/                 Data layer (no ImGui) — one model per .dat file
      ByteIO.{h,cpp}      Endian read/write helpers + file IO
      ItemsFile.{h,cpp}   items.dat   (256 * 20)  — fully decoded
      MonstersFile.{h,cpp}monsters.dat(256 * 26)  — geometry + partial fields
      RosterFile.{h,cpp}  roster.dat  (64 * 130)  — confirmed layout (LE)
      MapFile.{h,cpp}     map.dat     (60 * 512)  — visual + collision pages
      AttribFile.{h,cpp}  attrib.dat  (60 * 64)   — partial (env + roof bits)
      StrFile.{h,cpp}     str.dat     (text pool) — (byte+0x1C)&0xFF transform
      RawFile.h           generic byte container (spells/event)
      AreaNames.h         60 map/area names + env-type decode (from b3dmm2)
      Gfx.{h,cpp}         planar image-chunk decoder for .32 and .anm
    sections/             UI layer — one editor per data type
      ItemsSection, MonstersSection, RosterSection, MapSection,
      AttribSection, StrSection, RawSection (spells.dat, event.dat),
      GfxSection (.32 tilesets and .anm animations)
    widgets/
      HexView.{h,cpp}     shared scrollable hex+ASCII dump
      Texture.{h,cpp}     RGBA -> OpenGL texture helper for previews
  tests/
    gfx_dump.cpp          offline gfx-decoder validator (not in CMake build)

Graphics (.32 / .anm)

Both formats share a planar image-chunk codec (5 Amiga bitplanes, 32-color 0x0RGB palette, nibble-RLE pixel stream). .32 tilesets begin the chunk at offset 0; .anm animations carry a "TV" prelude and the chunk is located via an FF 00 marker. The Graphics (.32) and Animations (.anm) sections scan the data folder, decode the selected file, and preview frames (single + contact sheet), the palette, and per-frame metadata. Decoding is verified against real wall/UI .32 sheets via tests/gfx_dump.cpp. Note: globe.32 and disk.32 use the .32 extension in the resource table but are XOR data blobs (copy-protection strings / other), not planar image chunks. The .anm viewer also includes an experimental "Use prelude placement" toggle that draws each selected frame at its prelude (x,y) on a shared canvas for layout sanity checks without forcing a hard format interpretation.

Adding a new section

1. Add a core/XxxFile.{h,cpp} model with decode/encode/load/save.
2. Add a sections/XxxSection.{h,cpp} subclass of Section.
3. #include it and sections_.push_back(std::make_unique<XxxSection>()) in App::registerSections().
4. Reconfigure (the CMake glob picks up new files automatically).

Decode status (see EXTRACTED/docs and b3dmm2)

File	Status	Editor
items.dat	fully decoded	full field editor
roster.dat	layout confirmed (some unknown)	stats/equipment/spells tabs
str.dat	encoding decoded	text editor
monsters.dat	26-byte records; fields partial	name + named/raw fields
map.dat	512 B/screen confirmed	tile + collision grids
attrib.dat	partial (env + roof)	known fields + roof grid + hex
spells.dat	layout unknown	raw hex
event.dat	container decoded (python tool)	raw hex (structured TODO)