inside outside test in computer graphics | Area filling ODD-EVEN RULE, NON ZERO WINDING NUMBER RULE скачать в хорошем качестве

inside outside test in computer graphics | Area filling ODD-EVEN RULE, NON ZERO WINDING NUMBER RULE

In this video we will learn about Inside outside test in computer graphics. BASIC CONCEPT: Area-filling algorithms and other graphics processes often need to identify interior regions of objects. It is not always clear which regions of the x-y plane would be "interior" and which regions would be "exterior" to the object. This is because in the algorithms we can give the vertices of the fill area in any order which does not specify which region is interior and which is exterior. How to find out? There are 2 tests to find out if the region is interior or exterior. ODD-EVEN RULE also known as Odd parity rule. 2. Non-zero winding number. ODD-EVEN RULE In Odd-even rule we draw a line from any position P to a distant point outside the coordinate extents of the object and count the number of edges crossings along the line. If the number of edges crossed by the line is ODD then the Point P is in the interior. If the number of edges crossed by the line is EVEN then the Point P is in the exterior. CONDITION for Odd-even rule You need to make sure that the line drawn from the point P does not intersect a vertex or endpoint. NON ZERO WINDING NUMBER: In non-zero winding number method we need to know the direction of each edge in the polygon, i.e. whether the edge is clockwise or counter-clockwise. The winding number is number of times the polygon edges wind around a particular point in the counterclockwise direction. HOW to apply?? 1. To apply non zero winding number rule, first we keep the initial value of winding number=0. 2. Then we imagine drawing a line from point P to outside the polygon which does not pass through any vertex. 3. Now We add 1 to the winding number every time we intersect a polygon edge that crosses the line from right to left, and we subtract 1 every time we intersect an edge that crosses from left to right. The interior points are that have a non-zero value for the winding number. Exterior points are those whose value of the winding number is zero. PLEASE SUBSCRIBE!!!!! LIKE AND SHARE THIS VIDEO. THANK YOU!!!