OCCT Shapes

Occt category icon with logo interpretation


There are several shape types in OCCT and we will discuss them in this section. It is very important to understand the hierarchy of the shapes, being Vertex -> Edge -> Wire -> Face -> Shell -> Solid. You can use vertex'es to create the edge, then edges can be composed into the wires, and wires can be used to create faces. Faces can be used to create shells and closed shells can be used to create solids. This is the basic hierarchy of the shapes in OCCT. Compound shape is the special case of the shape that can contain any other shape type. It is used to group the shapes together. It is very useful when you want to apply the same operation to multiple shapes at once.

Is it possible to create a solid without creating a shell first?

Bitbybit contains a lot of helper functions to create the shapes of each category without you having to go through all these composition steps. You can create a cube directly by using the cube function, and you can create a cylinder by using the cylinder function. These functions will create the solid directly without you having to create the vertices, edges, wires, faces, and shell first. But you have to realise that any valid solid is composed of the shell, and the shell is composed of the faces, and the faces are composed of the wires, and the wires are composed of the edges, and the edges are composed of the vertices. So, in the end, you are creating all these shapes automatically in a more convenient way behind the scenes.