Find out whether points 1 and 2 are inside or outside a given polygon by examining the number of times a half-line drawn from a point intersects the polygon. The edges of the polygon are stored in an R-Tree.

In order to measure whether the points are inside or outside the polygon you must open those nodes of the R-Tree that intersect the half-line drawn from a point. The half-line can be drawn by selecting a point by mouse. You must examine the points in order.

A node of the R-tree can be selected by clicking it with the mouse. A selected node can be opened by clicking it again. When the algorithm finds intersection points, you must upkeep the number of points found in the counter below the visualization.

Whether a point is inside or outside the polygon can be answered in the pull-down menu.