Feb 14, 2017 poligon clipping sutherland hodgeman algorithm in hindi computer graphics. Disadvantages of sutherland hodgman polygon clipping. The term clipping is used to describe the process of finding whether a line or polygon is intersected by another polygon. Opengl glut lib sutherland hodgman c polygon clip free. A single polygon can actually be split into multiple polygons can you draw an example. Sutherlandhodgman algorithm each edge of the polygon must be testedagainst each edge of the clip rectangle.
The weileratherton algorithm overcomes this by returning a set of divided polygons, but is more complex and computationally more expensive, so sutherlandhodgman is used for many rendering applications. Sutherland hodgman polygon clipper by hamed sheidaian. Program to implement sutherlandhodgeman polygon clipping. Sutherlandhodgeman polygon clipping programs and notes. The code snippet seems to be taken directly from the corresponding wikipedia article. The output of a polygon clipper should be a sequence of vertices that define the clipped polygon boundaries. Sutherland hodgman algorithm contd the algorithm clips every polygon edge against each clipping line use an output list to store newly clipped polygon vertices with each polygon edge, 1 or 2 vertices are added to the output list s p. Sutherland hodgman polygon clipping algorithm pracspedia. Sutherlandhodgeman polygon clipping algorithm c program. Sutherland hodgman polygon clipping algorithm right clip boundary bottom clip boundary left clip boundary top clip boundary idea. In vertexarray is the array of input polygon vertices. Sutherland hodgman can also be extended into 3d space by clipping the polygon paths based on the boundaries of planes defined by the viewing. Clip a polygon by successively clipping against each infinite clip edge after each clipping a new set of vertices is produced. It allows clipping of any number of arbitrarily shaped subject polygons by any number of arbitrarily shaped clip polygons.
Php polygon clipper using the sutherlandhodgman algorithm. Sutherlandhodgeman polygon clipping this program is for implementing sutherlandhodgeman polygon clipping. Thus, an intersection point is calculated and saved. With this algorithm, given a list of input vertices and a list of planes, an output of. Consider each edge e of clipping area and do following. If both vertices are inside the clipping area save the second. With sutherland hodgman clipping, the polygon on the right is the desired. The algorithm steps from vertex to vertex, adding 0.
Explain sutherland hodgeman algorithm for polygon clipping. Clip polygon pto clipping edge foreachedge in polygon p check clipping cases there are 4 case 1. It is performed by processing the boundary of polygon against each window corner or edge. Polygon clipping sutherland hodgman algorithm a polygon can also be clipped by specifying the clipping window. Then draw a rectangular screen area, so that parts of the polygon are outside this area. These algorithms are able to clip polygons against irregular convex planefaced. An implementation of the sutherlandhodgman algorithm used for clipping polygons in c. It solves a series of simple and identical problems that, when combined, solve the. Input is in the form of vertices of the polygon in clockwise order. Computer graphics sutherlandhodgeman polygon clipping.
Two parallel methods for polygon clipping wiley online library. We can correctly clip a polygon by processing the polygon boundary as whole each window edge. This paper will also serve as a tutorial, instructing the readers to build a complete. Visualizing the sutherland hodgman algorithm harold serrano.
Polygon clipping algorithm by sutherland and hodgeman c program. The oldest one from 1974 is called the sutherlandhodgman algorithm. The task is to clip polygon edges using the sutherlandhodgman algorithm. If the first vertex is inside and the second is outside compute the intersection with the border of the clipping area and save it. That article explains the algorithm and it also explains the code. Vertices from the input list are inserted into an output list if they lie on the visible side of the. This is achieved by processing all polygon vertices against each clip rectangle boundary in turn. An efficient algorithm for line and polygon clipping springerlink. Polygon clipping is one of those humble tasks computers do all the time. To associate your repository with the polygonclippingalgorithm topic, visit. In geometry a polygon is a flat shape consisting of straightlines that are joined to form a circuit. The simple problem is to clip a polygon against a single infinite clip edge. 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. 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.
To generate first and follow for given grammar c programsystem programming and compiler constructionheres a c program to generate first and follow for a give grammar program. Clipping polygons the sutherlandhodgman algorithm clipping polygons would seem to be quite complex. There are several wellknown polygon clipping algorithms, each having its strengths and weaknesses. Sutherlandhodgeman polygon clipping programs and notes for mca. The sutherland hodgman algorithm is a wellknown algorithm for clipping a polygon against a rectangle. Program of cohen sutherland line clipping algorithm.
In this algorithm, all the vertices of the polygon are clipped against each edge of the clipping window. We need an organized way to dealwith all these cases. Apr 05, 20 sutherland hodgman algorithm each edge of the polygon must be testedagainst each edge of the clip rectangle. Clipping polygons the sutherland hodgman algorithm clipping polygons would seem to be quite complex. It solves a series of simple and identical problems that, when combined, solve the overall problem. Poligon clipping sutherland hodgeman algorithm in hindi computer graphics. The task is to clip polygon edges using the sutherland hodgman algorithm. In the second instance, no points are saved since they both lie on the back of the plane. Pdf polygon clipping and polygon reconstruction researchgate. Polygon clipping algorithm by sutherland and hodgeman c. There are 4 rules explained in sutherland hodgman algorithm for clipping polygons. The weileratherton algorithm overcomes this by returning a set of divided polygons, but is more complex and computationally more expensive, so sutherland hodgman is used for many rendering applications. A major application of clipping is to decide whether certain constructs fall within the display window.
Polygon clipping sutherlandhodgman algorithm geeksforgeeks. Php polygon clipping using the sutherlandhodgman algorithm clip. Sutherland and hodgmans polygonclipping algorithm uses a divideandconquer strategy. Polygon clipping sutherlandhodgmanpolygon clipping algorithm and weileratherton polygon clipping algorithm. Sutherlandhodgman can also be extended into 3d space by clipping the polygon paths based on the boundaries of planes defined by the viewing space. Multiplepolygons may result from clipping a singlepolygon. The sutherland hodgman algorithm performs a clipping of a polygon against each window edge in turn. Due to the size or complexity of this submission, the author has submitted it as a. It accepts an ordered sequence of verices v1, v2, v3. Sutherlandhodgman algorithm contd the algorithm clips every polygon edge against each clipping line use an output list to store newly clipped polygon vertices with each polygon edge, 1 or 2 vertices are added to the output list s p. 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.
Sutherland hodgeman polygon clipping the algorithm begins with an input list of all vertices in the subject polygon. The laingbarsky algorithm 1983 is a good deal more complicated, but in certain cases fewer intersections need to be calculated than for sutherland hodgman. 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. Sutherlandhodgman polygon clipping you are encouraged to solve this task according to the task description, using any language you may know. Unlike the sutherlandhodgman and weileratherton polygon clipping algorithms, the vatti algorithm does not restrict the types of polygons that can be used as subjects or clips. Sutherland and hodgman s polygon clipping algorithm uses a divideandconquer strategy. I wrote a php implementation of the polygon clipping algorithm by sutherlandhodgman. Application of sutherland hodgman polygon clipping. The sutherland hodgeman polygon clipping algorithm slideshare. It is used in computer graphics especially 2d graphics to reduce the complexity of a scene being displayed by eliminating parts of a polygon that do not. The full algorithm is given in c in the white book as figure 3. A convex polygon and a convex clipping area are given. Sutherlandhodgman polygon clipping unlike lineclipping where we selectively clipped against each edge, here we successively clip a polygon against all four edges of the clip rectangle s.
Sutherland hodgman polygon clipping algorithm author. This code clip a polygon with sutherlandhodgman algorithm. The vatti clipping algorithm is used in computer graphics. 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. Reentrant polygon clipping communications of the acm.
Polygon clipping and polygon reconstruction citeseerx. Php polygon clipping using the sutherlandhodgman algorithm. Mar 20, 2015 polygon clipping algorithm by sutherland and hodge. Sutherland hodgman polygon clipping university of helsinki. Request pdf two parallel methods for polygon clipping a control parallel and a novel data parallel implementation of the sutherlandhodgman polygon clipping algorithm are presented. To accomplish this task, it is not enough to clip the lines one by one with e. Its a basic operation in creating graphic output of all kinds. Sutherland hodgeman polygon clipping this program is for implementing sutherland hodgeman polygon clipping. The sutherlandhodgmanalgorithm is a wellknown algorithm for clipping a polygon against a rectangle. Consider the concave polygon in the picture below by just clipping the lines it is divided in several separate polygons.
Understanding sutherlandhodgman clipping for physics engines. A polygon can be clipped by processing its boundary as a whole against each window edge. Polygon clipping sutherland hodgmanpolygon clipping algorithm and weileratherton polygon clipping algorithm. There are 4 rules explained in sutherlandhodgman algorithm for clipping polygons.
Pdf polygon clipping is an important operation that computers. Sutherlandhogson polygon clipping javascript github. The sutherland hodgman algorithm is used for clipping polygons. Therefore, it may be somewhat faster when many polygon lines intersect with the clipping boundaries. Jun 19, 2016 2c using the previously generated polygon, repeat the sutherland hodgman algorithm to the right reference plane. Two parallel methods for polygon clipping request pdf. Sutherlandhodgman polygon clipping thesutherlandhodgmanalgorithmcorrectlyclips convex polygons,butconcave polygonsmaybe. Next, one side of the clip polygon is extended infinitely in both directions, and the path of the subject polygon is traversed. The algorithm proceeds in stages by passing each clipped polygon to the next edge of the windows and clipping. In polygon clipping, we use an algorithm that generates one or more closed areas that are then scan converted for the appropriate area fill.
Polygon clipping algorithm by sutherland and hodge. After discussing three basic polygon clipping algorithms, a different approach is proposed, explaining the principles of a new algorithm and presenting it step by step. An algorithm that clips a polygon is rather complex. The sutherland hodgeman polygon clipping algorithm. May 07, 2017 in this video we will learn sutherland hodgeman polygon clipping algorithm. Sutherland hodgeman polygon clipping algorithm is used for polygon clipping. Sutherlandhodgman polygon clipping for each window edge for each source edge clip each polygon edge against the window edge endfor reenter algorithm with clipped polygon endfor figure 2 shows four successive steps in the algorithm when a concave. This paper presents a new 2d polygon clipping method, based on an extension to the sutherlandcohen 2d line clipping method. April 04, 2015 computer graphics sutherland hodgeman polygon clipping algorithm c. The algorithm to perform sutherlandhodgeman clipping is very simple and easy to implement.
Program to show the implementation of cohen sutherland line clipping algorithm. Ericsons realtime collision detection book aka the orange book. Grab a piece of paper, and draw a convex polygon on it. Clip polygon pto clipping edge foreachedge in polygon p. Weileratherton polygon clipping convex polygons are correctly clipped by the sutherlandhodgman algorithm, but concave polygons may be displayed with extra areas area inside the red circle, as demonstrated in the following figure.
It spendsologp time on each edge of the clipped polygon, wherep is the number of window edges, while the sutherlandhodgman algorithm spendsop time. Demo realized through the panel properties to modify the world coordinates of the model, and then in the properties panel select cube corresponds to the surface and. In the first case, p1 is in front of the plane and p2 is on the back. Poligon clipping sutherland hodgeman algorithm in hindi.
Sutherland hodgeman polygon clipping algorithm c program. The sutherlandhodgman algorithm clips a polygon against all edges of the clipping region in turn. Polygon clipping and filling computer science department. Program to show the implementation of sutherland hodgeman polygon clipping. May 19, 2011 sutherland hodgeman polygon clipping the algorithm begins with an input list of all vertices in the subject polygon. The algorithm you present is not the sutherlandhodgmanalgorithm for clipping against an arbitrary polygon, but the cohensutherlandalgorithm for clipping against a rectangular viewport. Php polygon clipping using the sutherland hodgman algorithm clip. Program of sutherland hodgemann algorithm for polygon clipping. Unlike the sutherlandhodgman and weileratherton polygon clipping algorithms, the vatti algorithm does not restrict the types of polygons that can be used as. More than 50 million people use github to discover, fork, and contribute to over 100 million projects. The sutherlandhodgman algorithm is an algorithm used for clipping polygons. This is a part of mumbai university mca colleges computer graphics cg mca sem 2. In fact, clipping like this was necessary in my previous tutorial on building a.
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