To use a Polygon node, first create an Object node for the object whose polygon data you want to access. Click the Object node’s Outputs menu (red square) and choose Object from the menu that appears to create an Object port. Connect this Object port to the Polygon node’s Object port. Pass the number of the polygon that you want to access to the Polygon Index port
This index number corresponds to the numbering shown in the Structure manager. The node outputs the object’s number of polygons and the parameters of the indexed polygon.
The following output ports are available.
The object’s total number of polygons.
These four ports output the index numbers of the indexed polygon’s points. These are not the positions of the points, but their index numbers. To access the positions of the points, pass these index numbers to a Point node. If the polygon is a triangle, the fourth index point has the same value as the third. Thus you can check if a polygon is a triangle or quadrangle by comparing the third and fourth index points..
This gives the polygon’s normal vector. The normal vector is always perpendicular to the polygon’s surface and is exactly one unit in length.
This port outputs the position of the polygon center. You can choose between local and global point coordinates. In the Attribute Manager, choose the desired type from the Matrix Mode drop-down list.