GMD is the model format used by Atlus in Persona 5 and subsequent titles, such as Persona 4 Dancing All Night and it's successors (Persona 3 Dancing Moon Night and Persona 5 Dancing Star Night.) Unlike RMD, which was previously used in the PS2 titles and developed by Renderware, GMD stores animations externally in GAP format. However, GAP files can sometimes be stored in GMD files on certain occasions.
Below is a table with descriptions of texture maps in all games that use the GFD Engine
|Diffuse Map||Main texture. Usually called diffuse/color/albedo in other engines.|
|Normal Map||Normal map. Rarely used for stuff that isn't field models.|
|Specular Map||Usually called Gloss map in other engines. Simply overlays on top of diffuse when the camera is pointed directly at the spot that has some color (also needs to be lit up by some light sources ingame)|
|Reflection Map||Scrolling texture overlay. Field40 is reflectivity, aka the opacity of this overlay.|
|Highlight Map||Additional overlay texture, Ambient color decides the transparency, Field4D in the material decides the blend mode: 1 - Normal, 2 - Screen/Dodge, 4 - Multiply|
|Glow Map||Works like emission map in other engines, adding actual glow to parts of the model.|
|Shadow Map||Basically a texture that adds an overlay of pre-baked shadows. Usually called AO map in other engines. Alpha channel tells the game where to NOT render rim light.|
Materials texture info
Field49 is texture filtering: 0 - off, 1 - on, 2 - off, 3 - on, and so on.
Persona 5 Model and Animation importer
TGE created a maxscript that's intended to be used with Autodesk 3dsMax. It supports importing GMD meshes, rigging, materials, and even GAP animations. You can get it here. It currently does not support all animations or models with embedded EPLs used for particle effects. Skinning information may not always be perfectly retained and models may require manual tweaking.
GFD Studio (formerly known as AtlusGfdEditor) is a tool for viewing and converting skinned models to GMD format. Rigging and mesh/texture conversion is currently possible, as well as manipulation of material properties. GAP files are also supported, so you can import, export, replace and re-arrange animations within them. You can download the latest build here.
Blender Tools for GFS
A Blender tool by Pherakki for importing and exporting GFS, GMD, and GAP files, available here.