CAD — read by a geometry kernel
Render a BREP file in your browser
BREP is OpenCascade's own native format — and OpenCascade is the kernel Rendermio runs in your browser. A .brep file is read exactly, with nothing translated, and rendered on your machine.
How Rendermio reads BREP
Accepted as .brep. STEP, IGES and BREP go through a real boundary-representation kernel — OpenCascade, compiled to WebAssembly and run inside the page. The kernel reads the exact surfaces, then tessellates them at a tolerance tuned for jewellery (a bounding-box ratio of 0.0002 and an angular deflection of 0.12 radians), which is far finer than a viewer's default. That is why a curved band renders as a curve and not as a polyline of visible flats. BREP is the kernel's native serialisation, so there is no translation step at all: the shapes in the file are the shapes the kernel builds. It is the most exact of the three CAD formats, and also the rarest — it comes almost exclusively from FreeCAD and from tools built on OpenCascade.
What comes through
- Every shape exactly as it was saved, with no interchange loss
- Solids, shells and faces as the kernel understands them
- Compound structure, so a multi-body file arrives as separate parts
What does not
- Colours and names — BREP stores topology and geometry only, so every part arrives in the default metal until you dress it
- Anything from the application layer: FreeCAD's feature tree is not in the file
Exporting BREP from your CAD program
- From FreeCAD, export the Part or Body rather than the whole document if you want one thing rendered
- For colours and part names, export STEP AP214 from the same tool instead — same kernel, more metadata
BREP files typically come from FreeCAD, CadQuery and build123d, OpenCascade-based tools. Working in SolidWorks, Fusion, CATIA, Inventor or Creo? Their native files are not readable in a browser — here is what to export instead.
Then what happens
Once the file is in, the steps are the same for every format: tell the studio what the object is, and it dresses it — one click finds the stones in a ring and makes the rest gold. Pick a Look, which sets lighting, backdrop, pose and camera together. Export a listing pack up to 8K or a 360° turntable video. Everything runs on your own GPU; the file never leaves the page.
Questions
What is a .brep file?
The native file format of the OpenCascade geometry kernel: exact boundary representation with no application data. FreeCAD and code-CAD tools such as CadQuery write it. Rendermio reads it with the same kernel, so nothing is lost in translation.
Should I export BREP or STEP from FreeCAD for rendering?
Either renders identically. STEP AP214 additionally carries part names and colours, which saves a step in the studio, so it is the better default. BREP is the choice when you want the geometry exactly as the kernel holds it.
Does BREP work for jewellery files?
Yes, if your tool writes it. Most jewellery CAD (Rhino, MatrixGold) writes 3DM, STEP or STL instead; BREP is mainly a FreeCAD and code-CAD format.
Free · runs in your browser · your file is never uploaded