The modification so that lines may be clipped as well as polygons is included in this function. Martinezrueda polygon clipping algorithm, does boolean operation on polygons multipolygons, polygons with holes etc. Earclipping based algorithms of generating highquality polygon triangulation gang mei 1, john c. A major application of clipping is to decide whether certain constructs fall within the display window. Sutherland and hodgmans polygonclipping algorithm uses a divideandconquer strategy. A polygon clipper takes as input thevertices of a polygon and returns oneor morepolygons. We clip edge of the polygon in turn against the edge e of the 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. These algorithms are complex and the steps of calculation are very. Line and circle generationline generation dda and bresenhams algorithm, thick line segments, antialising of lines, circle generation dda and bresenhams algorithm, character generation.
We present an algorithm for clipping a polygon or a line against a convex polygonal window. In other words, we can say that computer graphics is a rendering tool for the generation and manipulation of. Concave polygon line clipping without degenerate edges. The sutherlandhodgman algorithm is a wellknown algorithm for clipping a polygon against a rectangle. The full algorithm is given in pascal in the white book as program 3. 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. Polygon clipping algorithm by sutherland and hodgeman c. Clip single polygon using single infinite clip edge repeat 4 times note the generality. Background weiler atherton polygon clipping algorithm is an algorithm made to allow clipping of even concave algorithms to be possible. The full algorithm is given in c in the white book as figure 3. Pdf polygon clipping is an important operation that computers,execute all the time. To accomplish this task, it is not enough to clip the lines one by one with e. It involves computations, creation, and manipulation of data.
A simple and efficient algorithm for line and polygon clipping in 2d computer graphics sushil chandra dimri professor and head graphic era university dehradun abstract the most popular lines clipping algorithms are cohensutherland and liangbarsky line clipping algorithm. Cases of the sutherland hodgman polygon clipping algorithm. The primary use of clipping in computer graphics is to remove objects, lines, or line segments that are outside the viewing pane. The goal of this note is to provides an introduction to the theory of computer graphics. The algorithm you present is not the sutherlandhodgman algorithm for clipping against an arbitrary polygon, but the cohensutherland algorithm for clipping against a rectangular viewport.
A single polygon can actually be split into multiple polygons can you draw an example. Polygon clipping and filling week 3, lecture 5 david breen, william regliand maxim peysakhov department of computer science drexel university 1 2 outline polygon clipping. Reentrant polygon clipping communications of the acm. The oldest one from 1974 is called the sutherlandhodgman algorithm. This document describes a c library implementation of a new polygon clipping algorithm. Best author books of computer graphics and multimedia techniques buy online at best price in jaipur, rajasthan, india. The outputtoinput function sets the resulting polygon of this step up to be the input polygon for next step of the clipping algorithm. Contains a subject wise list of programs which students find in engineering courses.
Books computer graphics and multimedia techniques books. The sutherland hodgeman polygon clipping algorithm. That article explains the algorithm and it also explains the code. The techniques used are descended from vattis polygon clipping method. In other words, we can say that computer graphics is a rendering tool for the generation and manipulation of images. These algorithms are able to clip polygons against irregular convex planefaced volumes in three dimensions. Basic conceptstypes of graphics devices, display file structure, display file interpreter, display processors, graphics file format, bmp, tiff, pcx, gif. Mar 20, 2015 polygon clipping algorithm by sutherland and hodgeman c program. Weileratherton polygon clipping the basic idea in this algorithm is that instead of always proceeding around the polygon edges as vertices are processed, we sometimes want to follow the window boundaries.
Which path we follow depends on the polygonprocessing direction clockwise or counterclockwise and whether the pair of. Polygon clipping algorithm by sutherland and hodgeman c program. 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 vertices of the polygon. Sutherland and hodgmans polygon clipping algorithm uses a divideandconquer strategy. Earclipping based algorithms of generating highquality. A closed polygon when clipped cthen we may get one or more open c d polygon or dlines. Pauline baker computer graphics book see other formats. Polygon clipping is one of those humble tasks computers do all the time.
The clipping polygon may take the form of a concave polygon containing holes. Polygon clipping algorithm divide and conquer idea. Subject and clip polygons may be convex or concave, selfintersecting, contain holes, or be comprised of several disjoint contours. The sutherlandhodgmanalgorithm is a wellknown algorithm for clipping a polygon against a rectangle. Earclipping based algorithms of generating highquality polygon triangulation 3 2 the proposed algorithms 2. Pdf outputsensitive parallel algorithm for polygon clipping. Pdf polygon clipping is one of the complex operations in computational geometry. Sutherlandhodgman can also be extended into 3d space by clipping the polygon paths based on the boundaries of planes defined by the viewing space. This algorithm can break a single polygon into multiple polygons connected by edges on the boundary of the clipping rectangle for display. Scan conversion and clipping, windows programming and sampling, 2d and 3d geometric transformation, 2d viewing, directx.
General clipping algorithm for concave polygons with holes produces multiple polygons with holes. Section 2 introduces the preliminary concepts and terms. It is a primitive operation in many fields such as geographic. This paper presents a new 2d polygon clipping method, based on an extension to the sutherlandcohen 2d line clipping method. Usually it clips the four edges in the boundary of the clip rectangle.
Its main benefits are efficiency, and simple data structure. Download book pdf algorithms for graphics and image processing pp 337357 cite as. Consider the concave polygon in the picture below by just clipping the lines it is divided in several separate polygons. 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.
Computer graphics 6 computer graphics is an art of drawing pictures on computer screens with the help of programming. Input is in the form of vertices of the polygon in clockwise order. For example, polygon classification could be used to choose between pointinpolygon algorithms in a ray tracer, to choose an output rasterization routine, or to select an algorithm for linepolygon clipping or polygonpolygon clipping. Opengl glut lib sutherland hodgman c polygon clip free. The task is to clip polygon edges using the sutherlandhodgman algorithm. May 11, 2011 program to implement sutherlandhodgeman polygon clipping algorithm may 11, 2011 vaibhavwp leave a comment go to comments program to implement sutherlandhodgeman polygon clipping algorithm. Theoretical and experimental analyses show that the. Pages in category polygon clipping algorithms the following 4 pages are in this category, out of 4 total. Sutherland hodgeman polygon clipping the algorithm begins with an input list of all vertices in the subject polygon. Computer graphics pdf computer graphics book pdf notes starts with the topics covering introduction of computer graphics. We should point out here that one cannot rely on the display device to achieve clipping for two reasons. Polygon clippingcollection of connected lines is considered aspolygon.
The sutherland hodgeman polygon clipping algorithm slideshare. The polygon clipping is required to deal different cases. As the sutherlandhodgman algorithm is a polygon clipping algorithm, it does not handle line clipping very well. An efficient algorithm for line and polygon clipping. Two parallel methods for polygon clipping university of athens. Explain sutherland hodgeman algorithm for polygon clipping. The code snippet seems to be taken directly from the corresponding wikipedia article.
The simplest algorithm, called ear clipping, is the algorithm described in this document. The algorithm steps from vertex to vertex, adding 0. For example, we shall allow the polygon in figure 1a to be described by one left. Tipper 1 and nengxiong xu 2 abstract a basic and an improved earclipping based algorithm for triangulating simple polygons and polygons with holes are presented. Polygon clipping and polygon reconstruction lehrgebiet. If you liked it pls make it a point to comment below.
Sutherlandhodgman polygon clipping you are encouraged to solve this task according to the task description, using any language you may know. The sutherlandhodgman algorithm clips a polygon against all edges of the clipping region in turn. A simple and efficient algorithm for line and polygon. This is a part of mumbai university mca colleges computer graphics. Its a basic operation in creating graphic output of all kinds. This paper introduces a new, general polygon clipping algorithm. A set of connected lines are considered as polygon. Sutherland hodgman polygon clipping algorithm pracspedia. We present an extension of the greinerhormann polygon clipping algorithm that. Sutherlandhodgeman polygon clipping programs and notes for mca. Clipping polygons the sutherlandhodgman algorithm clipping polygons would seem to be quite complex. An algorithm that clips a polygon is rather complex.
Polygon clipping sutherlandhodgman algorithm geeksforgeeks. Various algorithms have been developed for triangulation, each characterized by its asymptotic order as ngrows without bound. A convex polygon and a convex clipping area are given. In geometry a polygon is a flat shape consisting of straightlines that are joined to form a circuit. 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. This program is for implementing sutherlandhodgeman polygon clipping. Generally, an algorithm that can assume a specific polygon shape can be optimized to run much faster than a. Polygon clipping sutherlandhodgmanpolygon clipping algorithm and weileratherton polygon clipping algorithm. Sutherland hodgman polygon clipping algorithm author. Clipping simple polygons with degenerate intersections. An algorithm for polygon clipping, and for determining polygon intersections and unions. Sutherlandhodgman polygon clipping algorithm thanks again for watching. Computer graphics assignment help, polygon or area clipping algorithm, polygon or area clipping algorithm sutherlandhodgman algorithm there are different algorithms as liangbarsky, line clipping, weileratherton polygon clipping, which are fairly efficient in performing the job of clipping images.
Pdf polygon clipping and polygon reconstruction researchgate. Quite a few polygon clipping algorithms have been published. 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. The term clipping is used to describe the process of finding whether a line or polygon is intersected by another polygon. It solves a series of simple and identical problems that, when combined, solve the overall problem. A polygon can be clipped by processing its boundary as a whole against each window edge. Example of two polygons before a and after b executing the intersection phase. The viewing transformation is insensitive to the position of points relative to the viewing volume. Graphics polygon clipping algorithm by sutherland and hodgeman c program. Opengl glut lib sutherland hodgman c polygon clip search and download opengl glut lib sutherland hodgman c polygon clip open source project source codes from. A control parallel and a novel data parallel implemen. Next, one side of the clip polygon is extended infinitely in both directions, and the path of the subject polygon is traversed. 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. According to the page97 of the book, i should be testing whether it is on the left or on the right side of the clipping edge.
Input is in the form of vertices of the polygon in clockwise order examples. After clipping, the output segments may not be ordered, and the reconstruction. May 07, 2017 in this video we will learn sutherland hodgeman polygon clipping algorithm. 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. Sutherlandhodgman polygon clipping algorithm youtube. We present such an efficient algorithm for clipping arbitrary 2dpolygons. The sutherlandhodgman algorithm is a algorithm used for clipping polygons.
The algorithm demonstrates the practicality of various ideas from computational geometry. There are several wellknown polygon clipping algorithms, each having its strengths and weaknesses. May 19, 2011 sutherland hodgeman polygon clipping the algorithm begins with an input list of all vertices in the subject polygon. Creating a device and rendering vertices, modeling and 3d viewing, hidden surface removal hidden surface removal. The following example illustrate a simple case of polygon clipping. Weiler atherton polygon clipping algorithm geeksforgeeks. Program to implement sutherlandhodgeman polygon clipping. The algorithm you present is not the sutherlandhodgmanalgorithm for clipping against an arbitrary polygon, but the cohensutherlandalgorithm for clipping against a rectangular viewport. First, the display area may be only a subset of the display screen for example, a part of the screen may be. Unlike sutherland hodgman polygon clipping algorithm, this algorithm is able to clip concave polygons without leaving any residue behind. The best algorithm i have found that could solve my problem is the weileratherton algorithm but it is for clipping against a polygon with clockwise edges and all i have is an infinite line in 3d a plane missing direction info. It spendsologp time on each edge of the clipped polygon, wherep is the number of window edges, while the sutherlandhodgman algorithm spendsop time per edge. Polygon clipping and filling week 3, lecture 5 david breen, william regliand maxim peysakhov department of computer science drexel university 1 2 outline.