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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Learn how your comment data is processed. The Cohen-Sutherland algorithm uses a divide-and-conquer strategy. We will use 4-bits to divide the entire region.

Cohen Sutherland Line Clipping Algorithm in C and C++

Each bit in the code is set to either a 1 true or a 0 false. If the character is on the boundary of the clipping window, then we discard only that portion of character that is outside of the clipping window. To clip a line, we need to consider only its endpoints. On the other hand, if the endpoints had codes of andthe logical AND would beand the line could not be trivally rejected.

If the region is to the top of the window, the second bit of the code is set to 1.

Cohen Sutherland Line Clipping Algorithm in C and C++ – The Crazy Programmer

The Cohen—Sutherland algorithm is a computer-graphics algorithm used for line clipping. These codes identify location of the end point of line. Your email address will not be published. It is trivially accepted and needs no clipping.

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In this algorithm, all the vertices of the polygon are clipped against each edge of the clipping window. Line can be partially inside the window We will find intersection point and draw only that portion of line that is inside region. This clipping method is based on characters rather than entire string. Note that the outcodes for endpoints must be recalculated on each iteration after the clipping occurs.

In this type of graphics, images are stored bit by bit and hence it is named Bit-map graphics. Retrieved from ” https: For example, the outcode represents a point that is top-right of the viewport.

The Cohen—Sutherland algorithm can be used only on a rectangular clip window.

First the polygon is clipped against the left edge of the polygon window to get new vertices of the polygon. The code’s bits are set according to the following conditions:.

Viewing & Clipping

If it is partially outside the window, then. Each edge of the window defines an infinite line that divides the whole space into two half-spaces, the inside half-space and the outside half-spaceas shown below.

It employs parametric line representation and simple dot products. To determine whether endpoints are inside or outside a window, the algorithm sets up a half-space code for each endpoint. If both endpoints of a line lie inside the window, the entire line lies inside the window.

On the other hand, if both endpoints of a line lie entirely to one side of the window, the line must lie entirely outside of the window. If both codes arebitwise OR of the codes yields line lies completely inside the window: Let N clippjng be the outward normal edge E i. If the endpoint codes are andthe logical OR is and the line can not be trivally accepted.


Cohen–Sutherland algorithm – Wikipedia

For example, if an endpoint had a code of while the other endpoint had a code ofthe logical AND would be which indicates the line segment lies outside of the window. The concept of line clipping is same as point clipping. The bits in the 2D outcode represent: By using this site, you agree to the Terms of Use and Privacy Policy. By observing the original smiley face closely, we can see that there are two blue lines which are represented as B1, B2 and E1, E2 in the above figure.

This site uses Akismet to reduce spam. It can be trivially rejected. In all or none string clipping method, either we keep the entire string or we reject entire string based on the clipping window.

If the region is to the left of the window, the first bit of the code is set to 1. If the logical OR is zerothe line can be trivally accepted.

In this method if the string is entirely inside the clipping window, then we keep it.