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