Cohen-Sutherland Line Clipping Algorithm: When drawing a 2D line on screen, it might happen that one or both of the endpoints are outside. The primary use of clipping in computer graphics is to remove objects, lines, or line This algorithm is more efficient than Cohen-Sutherland algorithm. Department of Computing Science, Umeå University. Computer Graphics & Visualization. Overview. Clipping. ▫ Cohen-Sutherland line clipping algorithm.

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If both codes arebitwise OR of the codes yields line lies completely inside the window: If the character is on the boundary of the clipping window, then we discard that entire character and keep the rest string.

Cohen-Sutherland Line-Clipping Algorithm

To determine whether endpoints are inside or outside a window, the algorithm sets kine a half-space code for each endpoint. For other convex polygon clipping windows, use the Cyrus—Beck algorithm. The bits in the 2D outcode represent: First the polygon is clipped against the left edge of the graaphics window to get new vertices of the polygon. You May Also Like: Each end point of the line segment is then assigned the code of the region in which it lies.

This is one of the oldest and most popular line clipping algorithm. If to the rightthe third bit is set, and if to the bottomthe fourth bit is set.


The Cohen-Sutherland algorithm uses a divide-and-conquer strategy. It is trivially rejected and needs to be neither clipped nor dutherland.

It is trivially accepted and needs no clipping. Your email address will not be published. An outcode is computed for each of the two points in the line. These codes identify location of the end point of line.

It is a type of computer graphics that the computer uses to store and display pictures. To speed algorthm the process this algorithm performs initial tests that reduce number of intersections that must be calculated. Consider the following figure, where the rectangle indicates the window.

Cohen–Sutherland algorithm

If both codes have a 1 in the same bit position bitwise AND of the codes is notthe line lies outside the window. If the endpoint codes are andthe logical OR is and the line can not be trivally accepted. The primary use of clipping in computer graphics is to remove objects, lines, or line segments that are outside the viewing pane. These new vertices are used to clip the polygon against right edge, top edge, bottom edge, of the clipping window as shown in the following figure. A bitmap is a collection of pixels that describes an image.

Point clipping tells us whether the given point X, Y is within the given window or not; and decides whether we will use the minimum and maximum coordinates of the window.


Viewing & Clipping

If both endpoints of a line lie inside the window, the entire line lies inside the window. Learn how your comment data is processed. It employs parametric line representation and simple dot products. For example, the outcode represents a point that is top-right of the viewport. It can be trivially rejected.

As you proceed around the window, extending each edge and defining an inside half-space and an outside half-space, nine regions are created – the eight “outside” regions and the one “inside”region.

The line segment’s endpoints are tested to see if the line can be trivally accepted or rejected.

In line clipping, we will cut the portion of line which is outside of window and keep alyorithm the portion that is inside the window. Cohen-Sutherland Line Clipping The Cohen-Sutherland line clipping algorithm quickly detects and dispenses with two common and trivial cases.

This page was last edited on 7 Januaryat