Cohen sutherland clipping algorithm when drawing a 2d line, if one endpoint of the line is outside the screen, and the other inside, you have to clip the line so that only the part of it thats inside the screen remains. Problem demonstrate how cohen sutherland algorithm works for the line segment. Cohensutherland line clipping university of helsinki. Apply the cohen sutherland line clipping algorithm to clip the line segment with coordinates 30,60 and 60,25. It eliminates the lines from a given set of lines and rectangle area of interest view port which belongs outside the area of interest and clip those. Given a set of lines and a rectangular area of interest, the task is to remove lines which are outside the area. In this video, i have explained the a numerical t of the cohen sutherland line clipping algorithm. Weiler atherton polygon clipping algorithm geeksforgeeks. The nichollleenicholl algorithm is a fast lineclipping algorithm that reduces the chances of clipping a single line segment multiple times, as may happen in the cohen sutherland algorithm. Cohen sutherland algorithm divides a twodimensional space into 9 regions and then efficiently determines the lines and portions of lines that are inside the given rectangular area. This algorithm is more efficient than cohen sutherland line clipping algorithm and can be extended to 3dimensional clipping. The calcode routine generates the code same as in cohen sutherland algorithm for the point, which is passed as an argument, against the clipping window boundaries.
Cohen sutherland line clipping algorithm in hindi computer graphics lec45. Explain cohen sutherland line clipping algorithm in detail. Lecture on cohen sutherland line clipping algorithm solved example shambhunath group of institutions. Example of cohensutherland line clipping algorithm. This direct calculation is avoided by performing a binary search for the intersection by always. Cohen sutherland 0101 0010 cohen sutherland 14 0001 0010 cohen sutherland 15 0001 0000 cohen sutherland 16 0000 0000 17 parametric line clipping developed by cyrus and beck in 1978 used to clip 2d3d lines against convex polygonpolyhedron liang and barsky 1984 algorithm efficient in clipping upright 2d3d clipping regions. The cohen sutherland line clipping algorithm quickly detects and dispenses with two common and trivial cases.
Description the following line clipping algorithms. Numerical cohen sutherland line clipping algorithm. The liangbarsky algorithm is a line clipping algorithm. The cohen sutherland algo requires calculation of intersection of the line with the window edge. This algorithm uses the clipping window as shown in the following figure. Contribute to tabulapdftabula java development by creating an account on github. This algorithm is considered to be the faster parametric line clipping algorithm. It allows line clipping for nonrectangular windows, unlike cohen sutherland or nicholl le nicholl. Cohen sutherland algorithm with solved example studyresearch.
The cohen sutherland algorithm is a computergraphics algorithm used for line clipping. Cases the cohen sutherland line clipping algorithm is processed, as follows since, both the bitcodes for the end points p, q of the line segment cannot be equal to 0000. Find file copy path subramanian ev updates naming and added cs line clipping ff4feaa nov 20, 2014. And there will draw a line between the two pints and clipping the line between the box will be shown as output. For example, for the line segment l we choose p to be the bitcodes 1001.
Personally, i find the cohen sutherland algorithm to be easy on the math, and more beginner friendly, which is why i chose to start with that. Convex area of interest which is defined by a set of coordinates given in a clockwise fashion. Using these equations cyrus and beck developed an algorithm that is generated more efficient than the cohen sutherland algorithm. Line clipping set 1 cohen sutherland algorithm point clipping algorithm in computer graphics. This document explains how cohen sutherland line clipping algorithm works. When drawing a 2d line on screen, it might happen that one or both of the endpoints are outside the screen while a part of the line. The cohensutherland algorithm in this algorithm we divide the line clipping process into two phases. This is in fact the liangbarsky algorithm, which is an alternative clipping algorithm thats more efficient than cohen sutherland clipping. The cohensutherland algorithm is a computergraphics algorithm used for line clipping. Cohen sutherland is a line clipping algorithm which is used to clip out the extra portion of the line from view plane c program for line clipping using cohen sutherland algorithm. Cohen sutherland line clipping algorithm example author. Pdf cohen sutherland line clipping algorithm example kasun.
What are the disadvantages of cohen sutherland line. Cohen sutherland algorithm is a linear time complexity line clipping algorithm. Lecture on cohen sutherland line clipping algorithm solved. Cohen sutherland line clipping algorithm opengenus iq. Aman singh rawat on iteration method or fixed point iteration algorithm, implementation in c with solved examples. Cohensutherland line clipping algorithm slideshare. Cyrus beck is a line clipping algorithm that is made for convex polygons. The region code for point x, y is set according to the scheme.
Xmin, ymin and xmax,ymax be the starting and ending points of the window. We use the following concepts in this algorithm we can use the parametric equation of line and inequalities. Let v 1 v 2 v 3 v 4 v 5 v 6 be the clipping window and p 1 p 2 p 3 p 4 p 5 p 6 be the polygon. Apply the cohen sutherland line clipping algorithm to clip. Cohen sutherland for line clipping given a line segment s from p 0x 0,y 0 to p 1x 1,y 1 to be clipped against a window w if codep 0 and codep 1 is not zero, then s is trivially rejected if codep 0 or codep 1 is zero, then s is trivially accepted 0101 0001 0100 0110 1001 0010 1010 0000. In line clipping, we will cut the portion of line which is outside of window and keep only the portion that is inside the window. Example of cohen sutherland line clipping algorithm. Pdf cohen sutherland line clipping algorithm example. The clipping window is divided into a number of different areas, depending on the position of the initial point of the line. Visibleboth endpoints of the line lie within the window. This polygon clipping algorithm does not work for self intersecting polygons, although some methods have been proposed to be able to solve this issue also, and have successfully worked.
Otherwise we split the line segment into two pieces at a clipping edge and thus reject one part. Cohen sutherland line clipping algorithm is quite interesting. Line clipping set 1 cohensutherland algorithm geeksforgeeks. Each edge of the window defines an infinite line that divides the whole space into two. The main use of line clipping algorithm in computer graphics is to remove objects, lines or line segments that are outside of the display panel. All lines fall into one of the following clipping categories. It also removes the repeated clipping needed in cohen sutherland input. Let r be the rectangular window whose lower lefthand corner is at l 3, 1 and upper righthand corner is at r 2, 6. A simple example of line clipping can illustrate this idea.
If you like geeksforgeeks and would like to contribute, you can also write an article using contribute. Creates a cohen sutherland clipper with the given clip rectangle. The concept of line clipping is same as point clipping. Write a cprogram to implement cohen sutherland line clipping algorithm to clip a triangle with vertices 0, 0, 4, 5 and 6, 1. It is a more powerful algorithm than the cohen sutherland algorithm. Cohen sutherland line clipping program in c on april 17, 20. Sutherland and cohen subdivision line clipping algorithm. Write a cprogram to implement cohen sutherland line clipping algorithm to clip a triangle. Program for clipping a line using cohen sutherland algorithm. The algorithm divides a twodimensional space into 9 regions and then efficiently determines the lines and portions of lines that are visible in the central region of interest the viewport. To clip a line, we need to consider only its endpoints. Line clipping the concept of line clipping is same as point clipping. Let us assume that the starting point of the line segment is p whose bit code is not equal to 0000. To compile and run the code follow the below steps.
Clipping is a very important aspect of 3d graphics, and so in the 3d lines tutorial, this 2d clipping function is used often. For example, if an endpoint had a code of 1001 while the other endpoint had a. Users who have contributed to this file 145 lines 125 sloc 2. First we test whether both endpoints are inside and hence draw the line segment or whether both are left of, right of, below, or above then we ignore line segment.
The polygon clipper clips against four edges in succession, whereas the line clipper tests the outcode to see which edge is crossed, and clips only when necessary. Line clipping set 2 cyrus beck algorithm geeksforgeeks. Cohen sutherland algorithm is a line clipping algorithm that cuts lines to portions which are within a rectangular area. This set of computer graphics questions and answers for experienced people focuses on cohen sutherland line clipping. Note the difference between this strategy for a polygon and the cohen sutherland algorithm for clipping a line. It eliminates the lines from a given set of lines and rectangle area of interest view port which belongs outside the area of interest and clip those lines which are partially inside the area of interest. Numerical based on cohen sutherland line clipping algorithm. Nine regions are created, eight outside regions and one inside region. Cohen sutherland line clipping algorithm in hindi computer graphics lec45 duration. The cohensutherland algorithm uses a divideandconquer strategy. Which means clip the line which is not visible in window. Bresenhams method of circle drawing, midpoint circle algorithm, midpoint ellipse algorithm, midpoint criteria, problems of aliasing, endpoint ordering and clipping lines, scan converting circles, clipping lines algorithms cyrusbeck, cohen sutherland and liangbarsky, clipping polygons, problem with multiple components. Clipping is a process of removing a portion of a line or an object that falls outside of the specified region. If both endpoints of a line lie inside the window, the entire line lies inside the window.