The algorithm you present is not the sutherland hodgman algorithm for clipping against an arbitrary polygon, but the cohen sutherland algorithm for clipping against a rectangular viewport. The task is to clip polygon edges using the sutherlandhodgman algorithm. The sutherlandhodgman clipping algorithm finds the polygon that is the intersection between an arbitrary polygon the subject polygon and. Polygon clipping algorithm by sutherland and hodgeman c. The sutherland hodgman algorithm performs a clipping of a polygon against each window edge in turn. In the first case, p1 is in front of the plane and p2 is on the back. Background weiler atherton polygon clipping algorithm is an algorithm made to allow clipping of even concave algorithms to be possible.
Computer graphics sutherlandhodgeman polygon clipping. Thus, an intersection point is calculated and saved. That article explains the algorithm and it also explains the code. Sutherlandhodgman polygon clipping algorithm subproblem. The sutherland hodgeman polygon clipping algorithm. Clipping polygons the sutherland hodgman algorithm clipping polygons would seem to be quite complex.
Subramanian usage click on the canvas to seed the points of the polygon press d to draw the seeded polygon drag the mouse cursor to draw the required clip rectangle press c to clip the required polygon section. First of all entire polygon is clipped against one edge, then resulting polygon is considered, then the polygon is considered against the second edge, so on for all four edges. Multiplepolygons may result from clipping a singlepolygon. Sutherland hodgeman polygon clipping algorithm is used for polygon clipping.
Input is in the form of vertices of the polygon in clockwise order examples. Sutherlandhodgman polygon clipping algorithm thanks again for watching. Write advantages of sutherlandhodgman polygon clipping. Disadvantages of sutherland hodgman polygon clipping. Contains a subject wise list of programs which students find in engineering courses. The sutherland hodgman algorithm is a wellknown algorithm for clipping a polygon against a rectangle. The algorithm takes an input polygon and some clipping planes, and outputs a new polygon. Algorithm for each boundary b in l, r, t, b if p 1 outside and p 2 inside output intersection output p 2 if p 1 inside and p 2 inside output p 2 if p 1 inside and p 2 outside output intersection if p 1 outside and p 2 outside do nothing. In geometry a polygon is a flat shape consisting of straightlines that are joined to form a circuit. In the second instance, no points are saved since they both lie on the back of the plane. We will use the following algorithms for polygon clipping sutherland hodgeman polygon clipping algorithm. It steps from vertex to vertex and adds 0, 1, or 2 vertices at each step to the output list. Clip polygon pto clipping edge foreachedge in polygon p check clipping cases there are 4 case 1. Polygon clipping is a process in which we only consider the part which is inside the view pane or window.
Program to implement sutherlandhodgeman polygon clipping. This is achieved by processing all polygon vertices against each clip rectangle boundary in turn. Apr 08, 2011 sutherland hodgman polygon clipping 1the sutherland hodgman polygon clipping algorithm clips polygons against convex clipping windows. The sutherland hodgman algorithm is used for clipping polygons. Sutherland hodge man polygon clipping algorithm animated description, example,practice problems. The sutherland hodgman clipping algorithm finds the polygon that is the intersection between an arbitrary polygon the subject polygon and a convex polygon the clip polygon. It works by extending each line of the convex clip polygon in turn and selecting only vertices from the subject polygon that are on the visible side. Consider each edge e of clipping area and do following. Using this program clip the polygon against the rectangular window. In polygon clipping, we use an algorithm that generates one or more closed areas that are then scan converted for the appropriate area fill.
The oldest one from 1974 is called the sutherland hodgman algorithm. Next, one side of the clip polygon is extended infinitely in both directions, and the path of the subject polygon is traversed. We can correctly clip a polygon by processing the polygon boundary as whole each window edge. To accomplish this task, it is not enough to clip the lines one by one with e. Sutherlandhodgman polygon clipping algorithm youtube. Sutherland hodgman polygon clipping algorithm with numerical. Clipping any procedure which identifies that portion of a picture which is either inside or outside a picture is referred toas a clipping algorithm or clipping. Clipping polygons the sutherlandhodgman algorithm clipping polygons would seem to be quite complex. The output of a polygon clipper should be a sequence of vertices that define the clipped polygon boundaries. Sutherland hodgman polygon clipping university of helsinki. The sutherland hodgeman polygon clipping algorithm slideshare. It works by extending each line of the convex clip polygon. Sutherland hodgeman polygon clipping computer engineering.
The code snippet seems to be taken directly from the corresponding wikipedia article. Sutherlandhogson polygon clipping javascript github. Sutherlandhodgman polygon clipping you are encouraged to solve this task according to the task description, using any language you may know. In this algorithm, all the vertices of the polygon are clipped against each edge of the clipping window. Opengl sutherlandhodgman polygon clipping algorithm in. Sutherland hodgman polygon clipping algorithm pracspedia. Sutherland and hodgmans polygonclipping algorithm uses a divideandconquer strategy. Unlike sutherland hodgman polygon clipping algorithm, this algorithm is able to clip concave polygons without leaving any residue behind. A convex polygon and a convex clipping area are given.
Php polygon clipping using the sutherland hodgman algorithm clip. Let me explain the algorithm of sutherland hodgman using the above situation. Apr 05, 20 sutherland hodgman algorithm each edge of the polygon must be testedagainst each edge of the clip rectangle. A single polygon can actually be split into multiple polygons can you draw an example. Consider the concave polygon in the picture below by just clipping the lines it is divided in several separate polygons. The sutherlandhodgman algorithm is an algorithm used for clipping polygons. Understanding sutherlandhodgman clipping for physics engines. May 07, 2017 in this video we will learn sutherland hodgeman polygon clipping algorithm. It solves a series of simple and identical problems that, when combined, solve the overall problem. Sutherland hodgman polygon clipping algorithm clip boundary inside outside s boundary inside outside s p boundary inside outside p s i s clip boundary inside outside i p p added to output list i added to output list no output i and p added to output list p for each clip edge scan the polygon and consider the relation between successive. May 11, 2011 program to implement sutherland hodgeman polygon clipping algorithm may 11, 2011 vaibhavwp leave a comment go to comments program to implement sutherland hodgeman polygon clipping algorithm.
A polygon can be clipped by processing its boundary as a whole against each window edge. Polygon clipping sutherland hodgman algorithm a polygon can also be clipped by specifying the clipping window. The idea is to clip each line segment of the input polygon against one clipping plane at a time. The following example illustrate a simple case of polygon clipping.
Visualizing the sutherland hodgman algorithm harold serrano. Jun 19, 2016 2c using the previously generated polygon, repeat the sutherland hodgman algorithm to the right reference plane. The sutherlandhodgman algorithm clips a polygon against all edges of the clipping region in turn. It clips a polygon against all edges of the clipping region. Polygon clipping is one of those humble tasks computers do all the time. There are several wellknown polygon clipping algorithms, each having its strengths and weaknesses. Sutherland hodgman clipping algorithm, by wojciech mula. In this video, i have explained the a numerical on the sutherland hodgman polygon clipping algorithm. This image from wikimedia commons demonstrates this quite well. We clip edge of the polygon in turn against the edge e of the clipping. Input is in the form of vertices of the polygon in clockwise order. It is performed by processing the boundary of polygon against each window corner or edge.
We will remove or clip the part that is outside the window. Php polygon clipping using the sutherlandhodgman algorithm. We need an organized way to dealwith all these cases. Its a basic operation in creating graphic output of all kinds. Polygon clipping algorithm by sutherland and hodgeman c program. Explain sutherland hodgeman algorithm for polygon clipping.
May 19, 2011 sutherland hodgeman polygon clipping the algorithm begins with an input list of all vertices in the subject polygon. The sutherlandhodgman clipping algorithm finds the polygon that is the intersection between an arbitrary polygon the subject polygon and a convex polygon the clip polygon. The sutherland hodgman algorithm clips a polygon against all edges of the clipping region in turn. The algorithm steps from vertex to vertex, adding 0. Sutherlandhodgeman polygon clipping ecomputernotes. It accepts an ordered sequence of verices v1, v2, v3. Sutherlandhodgeman polygon clipping algorithm c program. Sutherland and hodgmans polygonclipping algorithm uses a. Animated way to sutherland hodge man polygon clipping. Polygon clipping sutherlandhodgman algorithm geeksforgeeks. It solves a series of simple and identical problems. The advantages of sutherland hodgman algorithm are. Weiler atherton polygon clipping algorithm geeksforgeeks.