Smoothing Groups will be available starting from CRYENGINE 3.6.5.
The smoothing group tool is for assigning numbers to faces. The faces with same numbers and being connected with an edge are rendered smoothly. On the other hand a seam is displayed between two faces with different smoothing group IDs.
This tool is located under the texture category on the Designer Menu panel.
The UI layout is similar to that of 3ds Max's smoothing group panel as follows but the behaviors are rather different.
These number buttons are used to assign a number to the selected faces. Basically a face can belong into only one smoothing group. But you can select multiple number buttons holding Ctrl key to select faces by smoothing groups.
One object can have 32 smoothing groups.
You can select faces based on the selected number buttons. When you click this button, the faces belonging to the selected numbers will be selected.
The assigned smoothing Groups of the selected faces will be removed with this function.
This tool sets the smoothing groups based on the angle between faces. Any two faces will be put in the same smoothing group if the angle between their normals is lees than the threshold angle which can be adjusted in the Threshold edit box next to this button.
This threshold value is used for the Auto Smooth. This value specifies the maximum angle of two normals between two faces that determines whether those faces will be put in the same smoothing group.