Convert B3D to USDA
Free, in your browser, with nothing uploaded. Drop your .b3d file in and take the .usda away.
Drop your B3D file here
.b3d in, .usda out
Choose filesNothing is uploaded No account, no email No file size limit
How to convert B3D to USDA
- 01
Add your .b3d file
Drag your BlitzBasic 3D file onto the drop zone, or click it to browse. Nothing is uploaded: it is read where it already sits.
- 02
Check the preview
The model is parsed on your machine and drawn in the viewport, so a wrong axis or a missing texture shows up before you commit rather than downstream.
- 03
Save the .usda file
Press convert. The Universal Scene Description (ASCII) file is written in the tab and lands in your downloads folder. No link, no expiry, no account.
What carries over, and what does not
A format conversion is a translation, and translations lose things. Here is what actually happens when a B3D file becomes a USDA file.
| Data | B3D | USDA | Survives |
|---|---|---|---|
| Geometry | Yes | Yes | Yes |
| Materials & colour | Yes | Yes | Yes |
| Texture maps | Yes | Yes | Yes |
| Animation & rigs | Yes | Yes | Yes |
| Scene hierarchy | Yes | Yes | Yes |
This is a comparatively lossless pairing: 5 of the five categories above are supported by both formats, so most of what is in your B3D file has somewhere to go in the USDA file.
What our USDA writer puts in the file
One flat layer holding geometry, per-mesh UsdPreviewSurface materials and texture coordinates, with nothing referenced from outside the file. Texture images are not written, because a .usda names an image by path rather than carrying it; USDZ is the packaged form of the same scene and does carry them. Animation is not written, and the scene is flattened to one Mesh prim per mesh with transforms baked in.
About BlitzBasic 3D
B3D is the model format of Blitz3D, a BASIC dialect with a 3D engine bolted on that taught a generation of hobbyists to make games. It stores meshes, textures, bones and animation in a compact chunked binary, and several open-source engines still read it.
Commonly seen in: Blitz3D, BlitzMax, Irrlicht, hobbyist engines. More on the B3D format page.
About Universal Scene Description (ASCII)
A .usda file is Universal Scene Description in its human-readable text encoding. It is the flavour to reach for when you want to see what a scene actually declares, diff two revisions in source control, or hand-edit an override, at the cost of being far larger and slower to load than the binary crate format.
Commonly seen in: Houdini, Maya, usdview, Omniverse, Blender. More on the USDA format page.
How the conversion works
When you drop a file in, the bytes are handed to a parser compiled to run in your browser. The B3D data is decoded into an in-memory scene graph of meshes, materials and transforms, which is what the preview is drawing. Pressing convert walks that scene graph back out through a USDA writer and hands you the resulting bytes as a download.
The whole round trip is local. The page itself is static: it is delivered once and then does its work offline. That is why the privacy claim is checkable rather than a promise.
B3D to USDA: common questions
Is my B3D file uploaded anywhere?
No. The file is read by code running inside this browser tab and never crosses the network. You can prove it by disconnecting from the internet before you convert, the page keeps working, or by watching the Network tab in your browser's developer tools while you drop a file in.
How large a B3D file can I convert?
There is no server-side limit because there is no server. The practical ceiling is your own machine's memory: a browser tab can usually handle models up to a few hundred megabytes. Very dense scans or scenes with millions of triangles will take a few seconds and a lot of RAM.
Why does my converted USDA file look untextured?
Because this writer leaves them out. USDA references an image by filename rather than storing it inside the file, so the images would have to travel separately and land where the file expects them, which is how a converted model arrives broken. Convert to GLB, FBX or USDZ instead if the textures need to stay with the model.
Does it cost anything?
No. There is no fee, no account, no watermark and no per-file limit. Since the conversion runs on your hardware rather than ours, serving this page costs about as much as serving a blog post.
Does it work on a Mac, on Windows or on a phone?
All of them. There is nothing to install: any browser with WebGL 2 will do, which covers current Chrome, Edge, Firefox and Safari on desktop, and Safari and Chrome on mobile. A phone has less memory than a laptop, so a very heavy scene may be the one thing it cannot finish.
Related conversions
Other things to do with the same file.
From B3D:
Other ways to get to USDA:
Or do something else with it: