Unreal 3D File Format (.3d)
A 3D file holds mesh data for the original 1998 Unreal engine, split across a _d.3d data file storing polygons and texture coordinates and a paired _a.3d animation file storing whole-mesh vertex positions for every frame, with a companion .uc script assigning textures and animation sequences.
Unreal 3D at a glance#
| Full name | Unreal mesh |
|---|---|
| File extension | .3d |
| Category | 3D Models |
| Developer | Epic MegaGames |
| First released | 1998 |
| Compression | Uncompressed |
| FileFlip support | FileFlip does not handle this format |
What a .3d file can hold#
These are the things a Unreal 3D file either supports or does not, and they are what decides whether a conversion keeps everything or quietly drops something.
| Textures and materials | Yes |
|---|
Strengths and limitations of Unreal 3D#
What Unreal 3D does well
- Simple enough that its structure has been fully documented and reimplemented by fan tools decades later
- Compact vertex encoding, packing each animated vertex into a single 32-bit value
Where Unreal 3D falls short
- The generic "3D" extension is shared by unrelated formats from other applications, so it doesn't identify the format on its own
- Animation is a per-frame vertex snapshot, not a skeleton, so it can't be re-targeted or edited the way a rigged model can
- A _d.3d file is meaningless without its matching _a.3d animation file and usually the .uc script that assigns its textures
Use 3D only when working with original Unreal (1998) engine assets, since nothing outside that lineage produces or expects the format.
Convert 3D to OBJ or glTF to get a usable mesh out of an old Unreal asset for any modern tool.
How to open a .3d file#
A .3d file opens in the programs below, grouped by the platform you are on.
| Platform | Programs that open it |
|---|---|
| Web | FileFlip |
Unreal 3D questions people ask#
What is a 3D file from the original Unreal engine?
A 3D file is a mesh from the 1998 Unreal engine, split into a _d.3d file holding the polygon and texture-coordinate data and a matching _a.3d file holding vertex-animation frames. Epic MegaGames and Digital Extremes used this pair, alongside a .uc script for texture assignment, throughout the original Unreal.
Why do I need a .uc file to use a 3D file?
A .uc file assigns textures to a 3D mesh's faces and can trim or scale the model, information the 3D file itself doesn't carry. Without the matching .uc, a 3D mesh typically loads untextured.
Is Unreal's 3D file the same as other formats using the .3d extension?
No. "3D" is a generic extension that several unrelated applications have reused for their own formats over the years, so a .3d file needs to be checked against its source rather than assumed to be Unreal engine data.
Converting Unreal 3D files#
FileFlip cannot open a .3d file, so there is nothing to convert it into here. It appears on the site as something other formats can be converted to.
FileFlip does not write .3d files, so nothing on the site converts into this format. It works as a source only.
Every conversion runs inside your browser. The file is read from your disk, the work happens on your own machine, and nothing is uploaded. How FileFlip works names the engine behind each family and how to verify that for yourself.