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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In all or none string clipping method, either we keep the entire string or we reject entire string based on the clipping window. The algorithm divides a two-dimensional 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.
The numbers in the figure below are called outcodes. Reject line segment if any end point of line appears outside of any boundary. This site uses Akismet to reduce spam. 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. First the polygon is clipped against the left edge of the polygon window to get new vertices of the polygon.
In this algorithm, all the vertices of the polygon are clipped against each edge of the clipping window.
Consider the following figure, where the rectangle indicates the window. If the region is to the left of the window, the first bit of the code is set to 1. Read 2 corner points of the clipping window left-top and right-bottom as wx1,wy1 and wx2,wy2.
Graphifs the logical OR is zerothe line can be trivally accepted. Let N i be the outward normal edge E i. This page was last edited on 7 Januaryat The logical OR of the endpoint codes determines if the line is completely inside the window. Line can be completely outside of the window This line will be completely removed from the region. For better understanding let us consider the following example where we draw a smiley face using bit-map graphics.
We will use 4-bits to divide the entire region.
Cohen Sutherland Line Clipping Algorithm in C and C++
Learn how your comment data is processed. It is a type of computer graphics that the computer uses to store and altorithm pictures. It employs parametric line representation and simple dot products. Now pick any arbitrary point P Ei on edge E i then the dot product N i. This clipping method is based on characters rather than entire string.
It can be trivially rejected. This is one of the oldest and most popular line clipping algorithm.
Cohen–Sutherland algorithm – Wikipedia
The first bit is set to 1 if the point is above algorithhm viewport. It is trivially rejected and needs to be neither clipped nor displayed. Views Read Edit View history.
For example, the outcode represents a point that is top-right of the viewport. Each of the nine regions associated with the window is assigned a 4-bit code to identify the region.
Each end point of the line segment is then assigned the code of the region in which it lies. The concept of line clipping altorithm same as point clipping.
To perform the trivial acceptance and rejection tests, we extend the edges of the window to divide the plane of the window into the nine regions. If both codes have a 1 in the same bit position bitwise AND xohen the codes is notthe line lies outside the window.