Free online GLB to BREP converter

What the GLB format is

GLB is the binary container form of glTF. It can store polygon meshes, materials, textures, cameras, lights, node transforms, and animations in one file. Blender, Autodesk 3ds Max, Maya, Unity, Unreal Engine, CAD visualization tools, web viewers, and 3D scanning applications commonly create or export GLB files.

GLB geometry is normally a triangulated surface mesh. Its units may be implied by the producing application, and its scene can contain multiple objects, hidden nodes, or nonuniform transforms. Those details must be resolved before importing the geometry into a CAD system.

What the BREP format is

BREP, usually stored with a .brep or .brp extension, represents a model through topological entities such as vertices, edges, wires, faces, shells, and solids. Open CASCADE Technology is a common implementation, and applications including FreeCAD and CAD kernels can read or write Open CASCADE BREP files.

BREP is useful for boundary checks, boolean operations, sectioning, volume calculations, and solid-model workflows. Unlike a mesh, it can describe analytic planes, cylinders, cones, and spheres. However, converting a GLB does not automatically create those analytic surfaces: each triangle generally becomes a separate planar face unless reconstruction or surface fitting is performed.

How to actually convert GLB to BREP

The most practical free desktop workflow uses Blender to decode the GLB and FreeCAD to create and export the BREP.

1. Open Blender and choose File → Import → glTF 2.0 (.glb/.gltf). Select the GLB file.
2. Remove cameras, lights, animation-only objects, and parts that should not enter the CAD model. Apply object transforms with Object → Apply → Rotation & Scale. Keep the original file because applying transforms can alter the scene representation.
3. Export the required geometry with File → Export → STL. Enable Selection Only when appropriate and enable Apply Modifiers. STL has no reliable unit declaration, so record the GLB scale before export.
4. Open FreeCAD and import the STL with File → Import. Use the Mesh workbench to inspect the triangles and check for holes, duplicated surfaces, inverted normals, or disconnected components.
5. Switch to the Part workbench, select the mesh, and choose Part → Create shape from mesh. Set a tolerance appropriate to the model scale; an unnecessarily large tolerance can close gaps or distort small features.
6. If the resulting shape is a closed shell, use Part → Convert to solid. This step fails or produces an unusable result when the mesh has open boundaries, self-intersections, overlapping faces, or inconsistent normals.
7. Select the resulting shape and use File → Export. Enter a filename ending in .brep or .brp, then confirm that the BREP/Open CASCADE format is selected if FreeCAD displays a format prompt.

For a quick conversion without installing software, upload the file to 101convert.com, select BREP as the output format, and download the generated file. Validate the result in the target CAD application because online converters may use different mesh-repair tolerances and may not preserve scene objects or scale.

Quality, compatibility, and limitations

• Mesh-to-BREP is usually faceted. A curved GLB object may become thousands of planar triangular faces rather than a cylinder, fillet, or free-form surface. This increases file size and can make CAD operations slow.
• A watertight mesh is required for a solid. Repair the mesh before conversion if FreeCAD cannot create a solid. Blender's mesh cleanup tools can remove loose geometry and recalculate normals, but dedicated mesh-repair software may be needed for complex scans.
• Materials and animation are discarded. BREP normally stores topology and geometry, not GLB textures, PBR materials, cameras, skinning, or animation.
• Check scale and orientation. GLB scenes commonly use meters, while CAD projects may use millimeters. STL does not preserve units, so apply the required scale in Blender or FreeCAD and measure a known dimension afterward.
• BREP is not universally identical across applications. Some programs use the word BREP for their own proprietary boundary model. If the receiving application expects a specific kernel or file variant, export to STEP or IGES instead when supported, then convert inside that application.