How to know if a model contains B-Rep or Tessellated bodies

CAD files embed two kind of data for the 3D bodies: BRep and Tessellation.

A BRep body is described by mathematical parameters and a topology. In order to display a BRep body, HOOPS Exchange evaluate the parameters and generate a tessellation. The BRep parameters are accessible in the PRC.

A Tessellated body, is simply a list of vertices organized in faces.

Depending on the format, the PRC you get from a HOOPS Exchange conversion may contains BRep, Tessellation or both.
The tessellation may be generated by HOOPS Exchange or extracted from the CAD data. More info


After the convertion of a model to PRC, you can identify which entities are B-Rep and which are tessellated bodies.

  • Traverse the tree to the Representation Item level
  • Check the Representation Item type
    • A3DRiPolyBrep: this is a tessellated body. In HOOPS Demo Viewer it is described as “Faceted solid”
    • A3DRiBrepModel: this is a B-Rep body, you can parse its parameters and explore its topology.
    • A3DRiSet: this a collection of A3DRiRepresentationItem. You need to check the type of the children of this entity.