Beginning with the initial set of polygon vertices, we could first clip the polygon against the left rect. Sutherlandhodgeman polygon clipping ecomputernotes. It is performed by processing the boundary of polygon against each window corner or edge. Polygon clipping algorithm by sutherland and hodgeman c.
The sutherlandhodgmanalgorithm is a wellknown algorithm for clipping a polygon against a rectangle. Sutherland hodgman polygon clipping algorithm with. 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. However, i wonder how to work sutherland hodgman algorithm in homogeneous system 4d i made a. Opengl glut lib sutherland hodgman polygon clip search and download opengl glut lib sutherland hodgman polygon clip open source project source codes from.
The task is to clip polygon edges using the sutherlandhodgman algorithm. Consider the concave polygon in the picture below by just clipping the lines it is divided in several separate polygons. Website to help it students to find and share their programs and notes. Or write the algorithm for sutherland hodgeman polygon. It accepts an ordered sequence of verices v1, v2, v3. In this video, i have explained the a numerical on the sutherland hodgman polygon clipping algorithm. Simple and easy uml diagrams for case studies to learn and share. The code snippet seems to be taken directly from the corresponding wikipedia article. Sutherlandhodgeman polygon clipping programs and notes. Sutherlandhogson polygon clipping javascript github. The sutherland hodgman algorithm performs a clipping of a polygon against each window edge in turn. It works by extending each line of the convex clip polygon.
This is a part of mumbai university mca colleges computer graphics cg mca sem 2. Home computer graphics program to implement sutherland hodgeman polygon clipping algorithm program to implement sutherland hodgeman polygon clipping algorithm may 11, 2011 vaibhavwp leave a comment go to comments. Sutherland hodgman polygon clipping algorithm author. Find file copy path fetching contributors cannot retrieve contributors at this time. Subdivision algorithm text clipping polygon sutherlandhodgeman polygon clipping weileratherton polygon clipping. Explain sutherland hodgeman polygon clipping algorithm with example. Computer graphics assignment help, sutherland hodgeman polygon clipping algorithm, what is clipping. I found when rectangle reach the real window width or height, it change direction rather than reach clipping width or height. Sutherland hodgman 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.
Consider each edge e of clipping area and do following. Polygon clipping is one of those humble tasks computers do all the time. Program to implement sutherlandhodgeman polygon clipping. Sutherlandhodgeman polygon clipping algorithm c program. Answer to write two opengl programclipping polygon, one use cohensutherland,anthoer use sutherlandhodgman to clipping po.
Home computer graphics program to implement sutherlandhodgeman polygon clipping algorithm program to implement sutherlandhodgeman polygon clipping algorithm may 11, 2011 vaibhavwp leave a comment go to comments. Find file copy path opengl clipping sutherland hodgeman polygon clipping. The oldest one from 1974 is called the sutherlandhodgman algorithm. Since there is only one output vertex list, the last vertex in. Sutherlandhodgman polygon clipping c project and source. This program is for implementing sutherlandhodgeman polygon clipping. Clipping in 3d computer graphics lecture slides docsity. Computer graphics sutherlandhodgeman polygon clipping.
Disadvantages of sutherland hodgman polygon clipping. In this algorithm, all the vertices of the polygon are. There is a program about animation with opengl in chapter 2. I dont understand why youre calling clip coordinates canonical space coordinates.
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. In realworld scene clipping can remove a substantial percentage of the environment from consideration. 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. There are several wellknown polygon clipping algorithms, each having its strengths and weaknesses. It is used in computer graphics especially 2d graphics to reduce the complexity of a scene being displayed by eliminating parts of a polygon that do not. Sutherland and hodgmans polygonclipping algorithm uses a divideandconquer strategy. 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. This is algorithm is used to clip the polygon which lies inside the window boundary.
The sutherlandhodgman algorithm clips a polygon against all edges of the clipping region in turn. The following c project contains the c source code and c examples used for sutherlandhodgman polygon clipping. Polygon clipping sutherland hodgman algorithm a polygon can also be clipped by specifying the clipping window. For this example, i think the size of window is 800 600, viewport region is also 800 600, and clipping region could be 10043100. Sutherlandhodgeman polygon clipping program in c march 2 february 3 january 7 2012 7 december 1 june 2 january 4 2011 3 december 3 awesome inc. Sutherlandhodgson polygon clipping algorithm using html5 canvas and javascript. Sutherlandhodgman polygonclipping 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. Explain sutherland hodgeman algorithm for polygon clipping. Top left and bottom right coordinates of the clipping window. That article explains the algorithm and it also explains the code. 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.
Print the sequence of points that define the resulting clipped polygon. This is achieved by processing all polygon vertices against each clip rectangle boundary in turn. It solves a series of simple and identical problems that, when combined, solve the overall problem. Input is in the form of vertices of the polygon in clockwise order. This is the source code of how to use opengl draw a polygon. The primary use of clipping in computer graphics is to remove objects, lines, or line segments that are outside the viewing pane. The viewing transformation is insensitive to the position of points relative to the viewing volume. To speed up the process this algorithm performs initial tests that reduce number of intersections that must be calculated. Sutherland hodgman polygon clipping university of helsinki. I marked 1, 2 below in opengl, the clipping is done by sutherlandhodgman. To accomplish this task, it is not enough to clip the lines one by one with e. Opengl sutherlandhodgman polygon clipping algorithm in. It does so by using a 4 bit code called as region code or outcodes. Gpu clipping takes place in 4d space aptly named clip coordinates before the perspective divide.
In one example application, consider an image editing program. This program is distributed in the hope that it will be useful, but without any warranty. Contains a subject wise list of programs which students find in engineering courses. Write advantages of sutherlandhodgman polygon clipping. After some investigation, i opted for the old and trusted sutherlandhodgman method to attack the problem.
Php polygon clipping using the sutherlandhodgman algorithm clip. The algorithm steps from vertex to vertex, adding 0. Opengl glut lib sutherland hodgman c polygon clip free. Its a basic operation in creating graphic output of all kinds. The following example illustrate a simple case of polygon clipping. Using this program clip the polygon against the rectangular window. The sutherlandhodgman clipping algorithm finds the polygon that is the intersection between an arbitrary polygon the subject. The first step is to identify the reference and the incident polygon. A single polygon can actually be split into multiple polygons can you draw an example. We can correctly clip a polygon by processing the polygon boundary as whole each window edge.
However, i wonder how to work sutherlandhodgman algorithm in homogeneous system 4d i made a. The algorithm you present is not the sutherlandhodgmanalgorithm for clipping against an arbitrary polygon, but the cohensutherlandalgorithm for clipping against a rectangular viewport. Clipping offers an important optimization also need to avoid setting pixel values outside of the range. Sutherland hodgeman polygon clipping algorithm, computer.
A convex polygon and a convex clipping area are given. It works by extending each line of the convex clip polygon in turn and selecting. Program of sutherland hodgemann algorithm for polygon clipping. I marked 1, 2 below in opengl, the clipping is done by sutherland hodgman. This is one of the oldest and most popular line clipping 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. Sutherland hodgeman polygon clipping algorithm is used for polygon clipping. Polygon clipping sutherlandhodgman algorithm geeksforgeeks. Solved clipping region in animation with opengl example. Contribute to evsubr opengl development by creating an account on github. It steps from vertex to vertex and adds 0, 1, or 2 vertices at each step to the output list. Visualizing the sutherland hodgman algorithm harold serrano.
1096 575 283 477 273 817 83 57 935 118 1263 496 317 679 1403 656 1354 493 85 1149 239 1473 1251 84 671 549 483 507 686 482 1281 1277 1020 94 1415 1474 717 698 1377 1217 98 1303 324