CG_IsPlanar — Check if a surface is or not planar
boolean CG_IsPlanar(geometry geom);
Availability: 3.5.0
            
            This method needs SFCGAL backend.
        
            
            This function supports 3d and will not drop the z-index.
        
            
            This function supports Polyhedral surfaces.
        
            
            This function supports Triangles and Triangulated Irregular Network Surfaces (TIN).