Program of sutherland hodgemann algorithm for polygon clipping. Application of sutherland hodgman polygon clipping, computer. Consider each edge e of clipping area and do following. The algorithm you present is not the sutherland hodgmanalgorithm for clipping against an arbitrary polygon, but the cohen sutherland algorithm for clipping against a rectangular viewport. May 19, 2011 sutherland hodgeman polygon clipping the algorithm begins with an input list of all vertices in the subject polygon. Sutherland hodgman polygon clipping algorithm right clip boundary bottom clip boundary left clip boundary top clip boundary idea. Polygon clippingcollection of connected lines is considered aspolygon. The code snippet seems to be taken directly from the corresponding wikipedia article. First the polygon is clipped against the left edge of the polygon window to get new vertices of the. Sutherlandhodgeman polygon clipping algorithm c program. If both vertices are inside the clipping area save the second if. The first polygon, the clipping polygon, is defined in terms of a series of edges.
The blue line represents a splitting plane in two dimensions. The clip boundary determines a visible and invisible region. The task is to clip polygon edges using the sutherland hodgman algorithm. In this algorithm, all the vertices of the polygon are clipped against each edge of the clipping window. We can correctly clip a polygon by processing the polygon boundary as whole each window edge. The subject polygon may be convex or concave whereas the clipping polygon must be convex. 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. Sutherland hodgeman polygon clipping algorithm is used for polygon clipping.
Input is in the form of vertices of the polygon in clockwise order. In polygon clipping, we use an algorithm that generates one or more closed areas that are then scan converted for the appropriate area fill. If the unclipped polygon lies completely outside the clipping boundary, the clipped polygon even has zero vertices. Barsky and maillot algorithms are better than the sutherland hodgman algorithm, but these algorithm only clip polygons against simple rectangles. What is sutherlandhodgman polygon clipping algorithm in. Polygon clipping free download as powerpoint presentation. The sutherland hodgmanalgorithm is a wellknown algorithm for clipping a polygon against a rectangle. A polygon clipping algorithm receives a polygon and a clipping window as input. Sutherland hodgman polygon clipping algorithm thanks again for watching. To accomplish this task, it is not enough to clip the lines one by one with e. The sutherlandhodgmanalgorithm is a wellknown algorithm for clipping a polygon against a rectangle. Hello friends, i am free lance tutor, who helped student in completing their homework. Program to show the implementation of liangbarsky line clipping algorithm. Polygon clipping and polygon reconstruction lehrgebiet.
The output of a polygon clipper should be a sequence of vertices that define the clipped polygon boundaries. Reentrant polygon clipping gettysburg college computer science. This is done by providing you with a complete type safety, integrated file and sample solution. Opengl sutherlandhodgman polygon clipping algorithm in. Easy tutor author of program to show the implementation of sutherlandhodgeman polygon clipping algorithm is from united states. I also guide them in doing their final year projects. Video explains with help of an example the working of the algorithm.
Program of cohen sutherland line clipping algorithm. Sutherlandhodgman polygon clipping algorithm youtube. The clip and the subject polygons are accessible through the head pointers headc and heads, respectively. Cases of the sutherland hodgman polygon clipping algorithm. There are 4 rules explained in sutherlandhodgman algorithm for clipping polygons. Polygon clipping an approach to simplified clipping. Polygon clipping algorithm by sutherland and hodgeman c program. Clipping polygons the sutherland hodgman algorithm clipping polygons would seem to be quite complex.
The sutherland hodgman clipping algorithm finds the polygon that is the intersection between an arbitrary polygon the subject polygon and a convex polygon the clip polygon. Application of sutherland hodgman polygon clipping. Php polygon clipper using the sutherlandhodgman 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. Program to show the implementation of cohen sutherland line clipping algorithm. Polygon clipping and filling computer science department. In vertexarray is the array of input polygon vertices. Clip a polygon by successively clipping against each infinite clip edge after each clipping a new set of vertices is produced. The paper analyzes the prevalent sutherlandhodgman algorithm for polygon clip ping and identifies cases for which this algorithm performs inefficiently.
A convex polygon and a convex clipping area are given. Then draw a rectangular screen area, so that parts of the polygon are outside this area. Pseudocode of sutherland and hodgmans polygon clipping algorithm. Clipping polygons the sutherlandhodgman algorithm clipping polygons would seem to be quite complex. Polygon clipping on images shows edges in pdf plots cad. The algorithm works iteratively by considering a clipping boundary and clips the entire polygon against this boundary. A description with examples for the sutherlandhodgman polygon clipping algorithm. Contains a subject wise list of programs which students find in engineering courses. Too slow does more work then necessary better to clip lines to window. Next, one side of the clip polygon is extended infinitely in both directions, and the path of the subject polygon is traversed. Sutherland hodgman polygon clipping you are encouraged to solve this task according to the task description, using any language you may know. This is achieved by processing all polygon vertices against each clip rectangle boundary in turn.
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. Sutherland hodgman polygon clipping pdf download, askeb abortus inkomplit pdf download 3d39b66ab9 sutherland hodgeman,algorithmthe. Pdf polygon clipping and polygon reconstruction researchgate. It is performed by processing the boundary of polygon against each window corner or edge. Could any one can help me about the example of source code for the sutherland hodgman method to polygon clipping. The oldest one from 1974 is called the sutherlandhodgman algorithm, as. The algorithm steps from vertex to vertex, adding 0, 1, or 2 vertices to the output list at each step. Program to show the implementation of sutherland hodgeman polygon clipping.
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. Sutherlandhodgman polygon clipping pseudo code for sutherl. A polygon can be clipped by processing its boundary as a whole against each window edge. Jun 19, 2016 2b using the generated polygon and the next reference plane, apply the sutherland hodgman clipping rule again. It accepts an ordered sequence of verices v1, v2, v3. The last vertex of the loopring points to the first record, in order to form the connected loop or ring in the data structure. Opengl glut lib sutherland hodgman polygon clip free open. 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. Sutherlandhodgman polygon clipping you are encouraged to solve this task according to the task description, using any language you may know. 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.
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. Sutherlandhodgeman polygon clipping this program is for implementing sutherlandhodgeman polygon clipping. Pdf polygon clipping is an important operation that computers,execute. The sutherland hodgman algorithm is used for clipping polygons. The algorithm to perform sutherlandhodgeman clipping is very simple and easy to implement. The algorithm you present is not the sutherlandhodgmanalgorithm for clipping against an arbitrary polygon, but the cohensutherlandalgorithm for clipping against a rectangular viewport. The following are the pages96 and page97 of the book schaums outline series of computer graphics the algorithm considers several things. 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. Visualizing the sutherland hodgman algorithm harold serrano. This clipping procedure was developed as a method for identifying visible surfaces, and so it can be applied with arbitrary polygonclipping regions. I wrote a php implementation of the polygon clipping algorithm by sutherlandhodgman.
If you liked it pls make it a point to comment below. A polygon can also be clipped by specifying the clipping window. The sutherland hodgman algorithm performs a clipping of a polygon against each window edge in turn. Program to show the implementation of sutherlandhodgeman. The second polygon, the subject polygon, is defined as a series of vertices. Sutherlandhodgeman polygon clipping programs and notes for mca.
Sutherland hodgman polygon clipping algorithm pracspedia. The algorithm steps from vertex to vertex, adding 0. May 30, 2014 a simple video that explains the working of sutherland hodgman polygon clipping algorithm in detail. Typically, any line or part thereof which is outside of the viewing area is removed. If you have an optimized program than listed on our site, then you can mail us with your name and a maximum of 2 links are allowed for a guest post. Computer graphics sutherlandhodgeman polygon clipping. My frame and xclipframe are set to 0 but when i pdf the drawings, the images that have used polygon for clipping show a pale grey line around them but the ones that use rectangle clipping are fine.
I inserted various images into a plot that required clipping to not cover other images. Vertices from the input list are inserted into an output list if they lie on the visible side of the. I have 4 years of hands on experience on helping student in completing their homework. Sutherlandhodgeman polygon clipping programs and notes. In the second case, p1 is in front of the plane, but p2 is on the back of the plane. This is a part of mumbai university mca colleges computer graphics cg mca sem 2. The sutherlandhodgman algorithm clips a polygon against all edges of the clipping region in turn.
Search tutorials, articles, forum, interview faq, poll, links. The sutherland hodgman algorithm clips a polygon against all edges of the clipping region in turn. Could any one can help me about the example of source code for the sutherlandhodgman method to polygon clipping. Computer graphics assignment help, application of sutherland hodgman polygon clipping, for good understanding of the application of the rules specified above see the following figure, where the shaded region demonstrates the clipped polygon. Sutherland hodgeman polygon clipping this program is for implementing sutherland hodgeman polygon clipping. Sutherland hodgeman polygon clipping the algorithm begins with an input list of all vertices in the subject polygon. In computer graphics, line clipping is the process of removing lines or portions of lines outside an area of interest. A closed polygon when clipped cthen we may get one or more open c d polygon or dlines. According to the rule, an intersection point with the plane is. Clipping polygons n cohensutherland and liangbarsky clip line segments against each window in turn n polygons can be fragmented into several polygons during clipping n may need to add edges n need more sophisticated algorithms to handle polygons. Explain sutherland hodgeman algorithm for polygon clipping. Polygon clipping algorithm by sutherland and hodgeman c. Program to implement sutherlandhodgeman polygon clipping.
Grab a piece of paper, and draw a convex polygon on it. An algorithm for polygon clipping, and for determining. A case 1 case 4 inside outside b a b inside outside a a b inside outside a. Let me explain the algorithm of sutherland hodgman using the above situation. The algorithm to perform sutherland hodgeman clipping is very simple and easy to implement. For a polygon to be clipped against a rectangle there would be 4. Sutherlandhodgeman polygon clipping ecomputernotes. A polygon clipper takes as input thevertices of a polygon and returns oneor morepolygons. Polygon clipping sutherlandhodgman algorithm geeksforgeeks. In geometry a polygon is a flat shape consisting of straightlines that are joined to form a circuit. 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. Notice that the clipped polygon often will have more vertices than the unclipped one, but it can also have the same number, or less. Understanding sutherlandhodgman clipping for physics engines. One such algorithm is sutherland hodgeman polygon clipping in which it abandons thinking of a polygon as a set of line segments and clipping individual edges.
827 595 1060 75 1328 150 1039 258 937 1195 143 431 1587 618 386 334 1305 1131 253 974 254 200 1198 1145 437 55 758 258 932 1285 1080 1094 502 594 727 845 925 233 922 602 1180 1424 639 811 711