For other convex polygon clipping windows, cyrusbeck algorithm is used. It is performed by processing the boundary of polygon against each window corner or edge. May 07, 2017 in this video we will learn sutherland hodgeman polygon clipping algorithm. The cohensutherland algorithm can be used only on a rectangular clip window.
Let me explain the algorithm of sutherland hodgman using the above situation. Php polygon clipping using the sutherland hodgman algorithm clip. Application of sutherland hodgman polygon clipping, computer. Implement polygon clipping using sutherlandhodgeman algorithm. Php polygon clipping using the sutherlandhodgman algorithm. 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. Consider the concave polygon in the picture below by just clipping the lines it is divided in several separate polygons. If the polygon is not also convex, there may be some dangling.
Program of sutherland hodgemann algorithm for polygon clipping. Polygon clipping sutherland hodgman algorithm a polygon can also be clipped by specifying the clipping window. It solves a series of simple and identical problems that, when combined, solve the overall problem. This code clip a polygon with sutherland hodgman algorithm. 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 a convex polygon the clip polygon. The algorithm you present is not the sutherlandhodgmanalgorithm for clipping against an arbitrary polygon, but the cohensutherlandalgorithm for clipping against a rectangular viewport. Sutherland hodgman polygon clipper by hamed sheidaian from. A convex polygon and a convex clipping area are given. The sutherland hodgman algorithm is a wellknown algorithm for clipping a polygon against a rectangle. This algorithm does not work if the clip window is not convex. In the first case, p1 is in front of the plane and p2 is on the back. Sutherlandhodgeman polygon clipping algorithm c program.
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. Cases of the sutherland hodgman polygon clipping algorithm. This code clip a polygon with sutherlandhodgman algorithm. Php polygon clipping using the sutherlandhodgman algorithm clip. Sutherlandhogson polygon clipping javascript github. Sutherland hodgeman polygon clipping the algorithm begins with an input list of all vertices in the subject polygon. Sutherland and hodgmans polygonclipping algorithm uses a divideandconquer strategy. Php polygon clipper using the sutherlandhodgman algorithm. The sutherlandhodgman algorithm clips a polygon against all edges of the clipping region in turn. The oldest one from 1974 is called the sutherlandhodgman algorithm. Due to the size or complexity of this submission, the author has submitted it as a.
In vertexarray is the array of input polygon vertices. Program to illustrate the implementation of 3d rotation transformation along. Sutherland hodgman can also be extended into 3d space by clipping the polygon paths based on the boundaries of planes defined by the viewing space. The sutherland hodgman algorithm performs a clipping of a polygon against each window edge in turn. Jun 19, 2016 2c using the previously generated polygon, repeat the sutherland hodgman algorithm to the right reference plane. Explain sutherland hodgeman algorithm for polygon clipping. The laingbarsky algorithm 1983 is a good deal more complicated, but in certain cases fewer intersections need to be calculated than for sutherland hodgman. Visualizing the sutherland hodgman algorithm harold serrano. Sutherland hodgeman polygon clipping algorithm is used for polygon clipping. Polygon clipping sutherlandhodgman algorithm point clipping algorithm in computer graphics. The simple problem is to clip a polygon against a single infinite clip edge.
Sutherlandhodgman polygon clipping you are encouraged to solve this task according to the task description, using any language you may know. That article explains the algorithm and it also explains the code. Computer graphics sutherlandhodgeman polygon clipping. Could any one can help me about the example of source code for the sutherlandhodgman method to polygon clipping. Polygon clipping algorithm by sutherland and hodgeman c program. Texturing, clipping reading texture mapping example texture map. Sutherland hodgeman polygon clipping this program is for implementing sutherland hodgeman polygon clipping. Opengl sutherlandhodgman polygon clipping algorithm in. Polygon clipping algorithm by sutherland and hodgeman c. To accomplish this task, it is not enough to clip the lines one by one with e. Sutherland and hodgmans polygonclipping algorithm uses a. Clipping polygons the sutherlandhodgman algorithm clipping polygons would seem to be quite complex. Next, one side of the clip polygon is extended infinitely in both directions, and the path of the subject polygon is traversed.
It clips a polygon against all edges of the clipping region. Sutherland hodgman polygon clipping algorithm pracspedia. We can correctly clip a polygon by processing the polygon boundary as whole each window edge. Sutherlandhodgeman polygon clipping this program is for implementing sutherlandhodgeman polygon clipping. Using this program clip the polygon against the rectangular window. Program to implement sutherlandhodgeman polygon clipping.
Clip polygon pto clipping edge foreachedge in polygon p check clipping cases there are 4 case 1. A single polygon can actually be split into multiple polygons can you draw an example. 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. Im not quite sure whether you understood the sutherlandhodgman algorithm correctly or at least i didnt get your example. Sutherlandhodgeman polygon clipping programs and notes for. Max is a declared constant procedure sutherlandhodgmanpolygoclip invertexarray. Sutherland and hodgman s polygon clipping algorithm uses a divideandconquer strategy. Opengl glut lib sutherland hodgman polygon clip free open. The sutherlandhodgmanalgorithm is a wellknown algorithm for clipping a polygon against a rectangle. Sutherlandhodgeman polygon clipping programs and notes for mca.
It accepts an ordered sequence of verices v1, v2, v3. 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. Disadvantages of sutherland hodgman polygon clipping. Solved clipping region in animation with opengl example. The output of a polygon clipper should be a sequence of vertices that define the clipped polygon boundaries. Let me explain the algorithm of sutherlandhodgman using the above situation. Sutherlandhodgman can also be extended into 3d space by clipping the polygon paths based on the boundaries of planes defined by the viewing space.
A polygon can be clipped by processing its boundary as a whole against each window edge. Sutherlandhodgeman polygon clipping ecomputernotes. The algorithm steps from vertex to vertex, adding 0. Mar 20, 2015 polygon clipping algorithm by sutherland and hodge. Input is in the form of vertices of the polygon in clockwise order. This is achieved by processing all polygon vertices against each clip rectangle boundary in turn. There are several wellknown polygon clipping algorithms, each. We will be discussing cyrusbeck algorithm in next set.
Program of liang barsky algorithm for line clipping. The sutherland hodgman algorithm is used for clipping polygons. This program is a simple opengl program, and draw a glass model of the red and blue color, and staggered some distance display, water cup autorotate feature, after configuring opengl environment vs2010 be able to compile the source program is running, and source code related to the opengl function. I wrote a php implementation of the polygon clipping algorithm by sutherlandhodgman. It steps from vertex to vertex and adds 0, 1, or 2 vertices at each step to the output list.
Two possible cases in bresenhams line drawing algorithm. There is a program about animation with opengl in chapter 2. Vertices from the input list are inserted into an output list if they lie on the visible side of the. For this example, i think the size of window is 800 600, viewport region is also 800 600, and clipping region could be 10043100. The task is to clip polygon edges using the sutherland hodgman algorithm. Write advantages of sutherlandhodgman polygon clipping. Program to show the implementation of liangbarsky line clipping algorithm. In polygon clipping, we use an algorithm that generates one or more closed areas that are then scan converted for the appropriate area fill.
This is a part of mumbai university mca colleges computer graphics cg mca sem 2. We need an organized way to dealwith all these cases. Sutherland hodgman polygon clipping algorithm author. 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. In the second instance, no points are saved since they both lie on the back of the plane. Pseudo code given a list of edges in a clip polygon, and a list of vertices in a subject polygon, the following procedure clips the subject polygon against the clip polygon. May 30, 2014 a simple video that explains the working of sutherland hodgman polygon clipping algorithm in detail. What is sutherlandhodgman polygon clipping algorithm in. Clip polygon pto clipping edge foreachedge in polygon p. Video explains with help of an example the working of the algorithm.
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. In geometry a polygon is a flat shape consisting of straightlines that are joined to form a circuit. Sutherland hodgman polygon clipping university of helsinki. Multiplepolygons may result from clipping a singlepolygon.
Implementation of polygon filling using boundary fill algorithms. Apr 05, 20 sutherland hodgman algorithm each edge of the polygon must be testedagainst each edge of the clip rectangle. Use this algorithm to draw a line with endpoints 2, 3. Given geometry in the world coordinate system, how do we get it. The algorithm proceeds in stages by passing each clipped polygon to the next edge of the windows and clipping. Polygon clipping algorithm by sutherland and hodge. Therefore, it may be somewhat faster when many polygon lines intersect with the clipping boundaries. Program to show the implementation of sutherland hodgeman polygon clipping. Consider each edge e of clipping area and do following. The code snippet seems to be taken directly from the corresponding wikipedia article. Polygon clipping sutherlandhodgman algorithm geeksforgeeks.
It works by extending each line of the convex clip polygon. The advantages of sutherland hodgman algorithm are. Thus, an intersection point is calculated and saved. May 19, 2011 sutherland hodgeman polygon clipping the algorithm begins with an input list of all vertices in the subject polygon. Sutherlandhodgman algorithm each edge of the polygon must be testedagainst each edge of the clip rectangle. In this algorithm, all the vertices of the polygon are clipped against each edge of the clipping window. Pseudo code given a list of edges in a clip polygon, and a list of vertices in a subject polygon, the following. A simple video that explains the working of sutherlandhodgman polygon clipping algorithm in detail. The sutherlandhodgman algorithm is an algorithm used for clipping polygons. The laingbarsky algorithm 1983 is a good deal more complicated, but in certain cases fewer intersections need to be calculated than for sutherlandhodgman.
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