RegionInfo() function - MapBasic - 2023

Purpose:

This function was created to determine the orientation of points in polygons―whether they are ordered clockwise, or counter-clockwise. The only attribute the function reports on is the 'direction' of the points in a specified polygon. You can call this function from the MapBasic window in MapInfo Pro.

Syntax:

RegionInfo( object, REGION_INFO_IS_CLOCKWISE, polygon_num )

Where:

	REGION_INFO_IS_CLOCKWISE    1

object refers to the object that is the subject of the function

REGION_INFO_IS_CLOCKWISE indicates whether the object is oriented in a clockwise or counterclockwise direction. A parameter of 1 indicates that the object is oriented in a clockwise order.

polygon_num indicates the polygon that is the subject of the function when an object contains more than one polygon.

Example:

If you were to select the state of Utah from States mapper and issued the following command in the MapBasic window, you would get a result of F or False, since the nodes in the single region of Utah are drawn in counter-clockwise order. Colorado's nodes are drawn in clockwise order and return T or True.

	print RegionInfo(selection.obj,1,1)