MS3D, ASE and COB files: three older 3D formats, and the Mac

Which file you have

Terminal shows the start of a file:

head -c 20 model.ase

The start matters, because other programs use .ase and .cob too. More on that in the sections below.

MS3D: MilkShape 3D

MilkShape 3D is a small Windows shareware modeller used for low-polygon models for games and mods. Its author is Mete Ciragan (chUmbaLum sOft). Its website no longer works: chumbalum.swissquake.ch doesn't even resolve to a server.

An .ms3d file is binary, with Windows byte order. It starts with the text MS3D000000 and a version number. It carries triangle meshes split into groups, materials with texture names, and a skeleton of joints with keyframe animation. Texture images are separate files. Vertex and triangle counts are 16-bit numbers, so one file holds at most 65,535 of each. The format is described only in a C header file by the program's author, now kept on paulbourke.net.

Blender up to version 2.79 could import and export MS3D with a built-in add-on; from 2.80 it's gone.

ASE: the text export from 3D Studio MAX

ASE is a readable text dump of a 3D Studio MAX scene, written by the ASCII Scene Export plug-in. This is how a triangle I wrote for testing starts:

*3DSMAX_ASCIIEXPORT	200
*COMMENT "AsciiExport Version  2.00 - test"
*SCENE {
	*SCENE_FILENAME "tri.max"
	*SCENE_FIRSTFRAME 0
	*SCENE_LASTFRAME 100
}
*MATERIAL_LIST {
	*MATERIAL_COUNT 1

Blocks in curly braces follow: objects with meshes (*GEOMOBJECT), cameras and lights, transforms (*NODE_TM), links to a parent object (*NODE_PARENT) and transform animation. Each face is a triangle with a smoothing group and a material number. Textures are paths to images. There's no official specification; Paul Bourke's page has only a sample file.

The Doom 3 engine read ASE too – its released source code contains an ASE reader, Model_ase.cpp.

Watch for clashes. According to FileInfo, four formats use the .ase extension: the 3D export from 3D Studio MAX, Adobe Swatch Exchange colour palettes, Aseprite sprites and Velvet Studio samples. Anyone with Illustrator has Adobe palettes on their Mac, because Illustrator ships them in its presets. The start of the file tells them apart: a 3D file starts with *3DSMAX_ASCIIEXPORT, an Adobe palette with the letters ASEF. macOS has several file types for .ase, and which one wins depends on the apps installed. So a double-click may open a different program than you expect. It's more reliable to open the file from the app, with File → Open.

COB: Caligari trueSpace

trueSpace was a Windows 3D program from Caligari, a company founded in 1985 with roots on the Amiga. Version 1.0 came out in 1994. Microsoft bought the company in early 2008 and discontinued trueSpace in May 2009.

A .cob file is an object; trueSpace saves a whole scene as .scn. The header starts with the word Caligari and the version V00.01. Then comes A for text or B for binary, followed by L or B for the byte order. Inside are chunks: PolH is a mesh, Mat1 a material, Grou a group, Lght a light and Came a camera. This is how a cube I wrote from the reader in the Assimp library starts:

Caligari V00.01ALH
PolH V0.08 Id 100 Parent 0 Size 00000000
Name Cube
…
World Vertices 8
0 0 0
10 0 0
…
Faces 6
Face verts 4 flags 0 mat 0
<0,0> <3,0> <2,0> <1,0>

COBOL source code uses the .cob extension too. You can tell a trueSpace model by the word Caligari at the start.

How to open them on a Mac

macOS doesn't know any of the three formats. On macOS 27.0.1 it has no file type of its own for .ms3d or .cob, the Model I/O framework loads none of them, and neither Preview, Quick Look nor the Finder shows them. MilkShape 3D, 3D Studio MAX and trueSpace run or ran only on Windows.

• Blender 2.79 still handles MS3D with its built-in add-on. It has no built-in support for ASE or COB.
• A text editor shows ASE and text COB files as numbers and keywords, but not the shape.
• Preview3D, my app, opens .ms3d, .ase and .cob files on a Mac in its window, in Quick Look and as Finder thumbnails. On iPad, iPhone and Apple Vision Pro too. So you can browse an old model collection as thumbnails.

Preview3D reads all three formats through the Assimp library. I tried it in the same build the app uses, with files I wrote from the descriptions above. MS3D version 4 opens, other versions don't: Assimp reports that it expects version 4. The ASE triangle opened. The text COB opened. According to its code Assimp reads binary COB as well, but I haven't tried that. A big-endian file, with a Caligari V00.01AB or …BB header, Assimp refuses. The app shows the geometry in one plain colour: it doesn't use the file's materials, textures, skeletons or animation. Model info has the dimensions in the file's units and the triangle count, plus a mesh check. On iPad and iPhone it stands the model on your desk in AR, fitted to the desk.

Converting to STL or OBJ

On a Mac, Preview3D converts from File → Export model as… (⌥⌘E) to STL, OBJ or PLY, without uploading anything. Materials, textures, skeletons and animation are dropped; only the shape stays. Game models are often built from separate parts and need repairs before printing; the mesh check shows where. Check the size in the slicer.

Common questions

What is an .ms3d file?

A model from MilkShape 3D, a Windows shareware modeller: a triangle mesh, materials, and a skeleton with animation in one binary file.

What is an .ase file, and why did it open in another app?

It's either a 3D scene from 3D Studio MAX, or an Adobe colour palette, an Aseprite sprite or a Velvet Studio sample. head -c 20 model.ase prints *3DSMAX_ASCIIEXPORT for a 3D file. Open it from the app with File → Open.

What is a .cob file?

An object from Caligari trueSpace, or COBOL source code. A trueSpace file starts with the word Caligari.

Why won't my .ms3d file open?

Assimp, and so Preview3D, reads only MS3D version 4. You'll find the version in the bytes right after the text MS3D000000.

Does a Mac open these files without another app?

No. macOS 27 shows none of them in Preview or Quick Look.

How do I convert them to STL or OBJ?

On a Mac, in Preview3D with File → Export model as…. Then check the mesh and the size.

Related pages

• The .3ds file – 3D Studio's binary format
• The .fbx file – today's format for moving scenes out of 3ds Max
• The .obj file – the text format old models are most often converted to

Sources

• Paul Bourke: the MilkShape 3D format – the author's header, versions 1.3 and 1.4
• Paul Bourke: ASE – a sample file
• PRONOM: Caligari trueSpace, text and binary
• Wikipedia: trueSpace – Caligari's history
• FileInfo: the .ase extension – four formats with one extension
• Assimp: reading MS3D, ASE and COB
• Blender 2.79: the MS3D add-on
• Doom 3 source code: the ASE reader

Have old models from MilkShape, 3D Studio MAX or trueSpace that won't open on your Mac? Write to me at apps@xfanta.com and tell me where they came from.