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. There are several wellknown polygon clipping algorithms, each having its strengths and weaknesses. Program to implement sutherlandhodgeman polygon clipping. Sutherland hodgman polygon clipping university of helsinki. 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. This program is distributed in the hope that it will be useful, but without any warranty. The sutherland hodgman algorithm is used for clipping polygons. Polygon clipping algorithm by sutherland and hodgeman c. We can correctly clip a polygon by processing the polygon boundary as whole each window edge. Print the sequence of points that define the resulting clipped polygon. Top left and bottom right coordinates of the clipping window.
Or write the algorithm for sutherland hodgeman polygon. Answer to write two opengl programclipping polygon, one use cohensutherland,anthoer use sutherlandhodgman to clipping po. Sutherland hodgman polygon clipping algorithm author. Solved clipping region in animation with opengl example. Simple and easy uml diagrams for case studies to learn and share. Php polygon clipping using the sutherlandhodgman algorithm clip. This is achieved by processing all polygon vertices against each clip rectangle boundary in turn. The following example illustrate a simple case of polygon clipping.
Program to show the implementation of sutherland hodgeman polygon clipping. Clipping, in the context of computer graphics, is a method to selectively enable or disable. Program of sutherland hodgemann algorithm for polygon clipping. It is performed by processing the boundary of polygon against each window corner or edge. This is one of the oldest and most popular line clipping algorithm. In one example application, consider an image editing program. The oldest one from 1974 is called the sutherlandhodgman algorithm. It accepts an ordered sequence of verices v1, v2, v3. The viewing transformation is insensitive to the position of points relative to the viewing volume. Contains a subject wise list of programs which students find in engineering courses. Its a basic operation in creating graphic output of all kinds. For this example, i think the size of window is 800 600, viewport region is also 800 600, and clipping region could be 10043100. Polygon clipping is one of those humble tasks computers do all the time.
Polygon clipping sutherland hodgman algorithm a polygon can also be clipped by specifying the clipping window. Opengl glut lib sutherland hodgman polygon clip free. The output of a polygon clipper should be a sequence of vertices that define the clipped polygon boundaries. 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. The first step is to identify the reference and the incident polygon.
Next, one side of the clip polygon is extended infinitely in both directions, and the path of the subject polygon is traversed. The sutherlandhodgman algorithm is an algorithm used for clipping polygons. I marked 1, 2 below in opengl, the clipping is done by sutherlandhodgman. Find file copy path opengl clipping sutherland hodgeman polygon clipping. To speed up the process this algorithm performs initial tests that reduce number of intersections that must be calculated.
There is a program about animation with opengl in chapter 2. Clipping polygons the sutherlandhodgman algorithm clipping polygons would seem to be quite complex. A polygon can be clipped by processing its boundary as a whole against each window edge. Sutherlandhodgeman polygon clipping algorithm c program. It works by extending each line of the convex clip polygon. Sutherlandhodgeman polygon clipping ecomputernotes. Disadvantages of sutherland hodgman polygon clipping. Sutherlandhodgman polygon clipping c project and source. Computer graphics assignment help, sutherland hodgeman polygon clipping algorithm, what is clipping. Police naik suhas sonawane has certainly added to the. In realworld scene clipping can remove a substantial percentage of the environment from consideration. Input is in the form of vertices of the polygon in clockwise order. Since there is only one output vertex list, the last vertex in.
However, i wonder how to work sutherlandhodgman algorithm in homogeneous system 4d i made a. That article explains the algorithm and it also explains the code. Contribute to evsubr opengl development by creating an account on github. Find file copy path fetching contributors cannot retrieve contributors at this time. Opengl sutherlandhodgman polygon clipping algorithm in. The sutherlandhodgman algorithm clips a polygon against all edges of the clipping region in turn.
Sutherland hodgman polygon clipping algorithm with. An implementation of the sutherlandhodgman algorithm used for clipping polygons in c. Opengl glut lib sutherland hodgman polygon clip search and download opengl glut lib sutherland hodgman polygon clip open source project source codes from. Consider the concave polygon in the picture below by just clipping the lines it is divided in several separate polygons. Explain sutherland hodgeman algorithm for polygon clipping. 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. 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. 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. A convex polygon and a convex clipping area are given. I dont understand why youre calling clip coordinates canonical space coordinates. It does so by using a 4 bit code called as region code or outcodes. The primary use of clipping in computer graphics is to remove objects, lines, or line segments that are outside the viewing pane. Polygon clipping sutherlandhodgman algorithm geeksforgeeks.
Opengl glut lib sutherland hodgman c polygon clip free. It steps from vertex to vertex and adds 0, 1, or 2 vertices at each step to the output list. A single polygon can actually be split into multiple polygons can you draw an example. 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. 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. Sutherland hodgeman polygon clipping algorithm, computer. The code snippet seems to be taken directly from the corresponding wikipedia article. Sutherlandhodgeman polygon clipping programs and notes. Clipping offers an important optimization also need to avoid setting pixel values outside of the range. In this algorithm, all the vertices of the polygon are. Write advantages of sutherlandhodgman polygon clipping. This program is for implementing sutherlandhodgeman polygon clipping. In polygon clipping, we use an algorithm that generates one or more closed areas that are then scan converted for the appropriate area fill.
Sutherlandhogson polygon clipping javascript github. Clipping in 3d computer graphics lecture slides docsity. However, i wonder how to work sutherland hodgman algorithm in homogeneous system 4d i made a. Sutherlandhodgson polygon clipping algorithm using html5 canvas and javascript. Beginning with the initial set of polygon vertices, we could first clip the polygon against the left rect. I marked 1, 2 below in opengl, the clipping is done by sutherland hodgman. This is a part of mumbai university mca colleges computer graphics cg mca sem 2. 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.
Website to help it students to find and share their programs and notes. 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. Sutherland and hodgmans polygonclipping algorithm uses a divideandconquer strategy. Explain sutherland hodgeman polygon clipping algorithm with example. The sutherlandhodgmanalgorithm is a wellknown algorithm for clipping a polygon against a rectangle.
Consider each edge e of clipping area and do following. This is algorithm is used to clip the polygon which lies inside the window boundary. To accomplish this task, it is not enough to clip the lines one by one with e. In this video, i have explained the a numerical on the sutherland hodgman polygon clipping algorithm. Visualizing the sutherland hodgman algorithm harold serrano.
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. The sutherland hodgman algorithm performs a clipping of a polygon against each window edge in turn. 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. After some investigation, i opted for the old and trusted sutherlandhodgman method to attack the problem. It works by extending each line of the convex clip polygon in turn and selecting.
The algorithm you present is not the sutherlandhodgmanalgorithm for clipping against an arbitrary polygon, but the cohensutherlandalgorithm for clipping against a rectangular viewport. 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. Gpu clipping takes place in 4d space aptly named clip coordinates before the perspective divide. It clips a polygon against all edges of the clipping region.