Explain Winding Number In Visualization?

Winding number method is used to check whether a given point is inside or out side the polygon. In this method give a direction number to all the edges which cross the scan line. If the edge starts below the line and ends above scan line give direction as -1 . otherwise1. Fr polygons or two dimensional objects, the point is said to be inside when the value of winding number is nonzero.

The winding number is the number of wraps (for clockwise wraps, the winding number is negative). The SVG computer graphics vector standard uses the non-zero rule by default when drawing polygons.