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