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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It is trivially rejected and needs to be neither clipped nor displayed. Consider the following figure, where the rectangle indicates the window.
Read 2 corner points of the clipping window left-top and right-bottom as wx1,wy1 and wx2,wy2. 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. In this method if the string is entirely inside the clipping window, then we keep it.
It is trivially accepted and needs no clipping.
Reject line segment if any end point of line appears outside of any boundary. Line can be completely outside of the window This line will be completely removed from the region.
If to the rightthe third bit is set, and if to the bottomthe fourth bit is set. These codes identify location of the end point of line. The Cohen—Sutherland clippiny is a computer-graphics algorithm used for line clipping.
Cohen Sutherland Line Clipping Algorithm in C and C++ – The Crazy Programmer
A polygon can also be clipped by specifying the clipping window. Let N i be the outward normal edge E i. Now pick any arbitrary point P Ei on edge E i then the fraphics product N i. 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 Cohen-Sutherland algorithm uses a divide-and-conquer strategy.
It is a type of computer graphics that the computer uses to store and display pictures. The first bit is set to 1 if the point is above the viewport.
If the logical AND of the endpoint codes is not zerothe line can be trivally rejected. You can connect with him clippnig facebook.
Line can be partially inside the window We will find intersection point and draw only graphcs portion of line that is inside region. This is one of the oldest and most popular line clipping algorithm. The numbers in the figure below are called outcodes. For example, the outcode represents a point that is top-right of the viewport.
Sutherland Hodgeman polygon clipping algorithm is used for polygon clipping.
It employs parametric line representation and simple dot products. This process is continued until the line is accepted. Various techniques are used to provide text clipping in a computer graphics.
Leave a Reply Cancel reply Your email address will not be published. To determine whether endpoints are inside or outside a window, the algorithm sets up a half-space code for each endpoint. Once we establish region codes for both the endpoints of a line we determine whether the endpoint is visible, partially visible or invisible with the help of ANDing of the region codes.
Cohen-Sutherland Line-Clipping Algorithm
If both codes have a 1 in the same bit position bitwise AND of the codes is notthe line lies outside the window.
The outcode will have 4 bits for two-dimensional clipping, or 6 bits in the three-dimensional case. If it is partially outside the window, then. The logical OR of the endpoint codes determines if the line is completely inside the window. You May Also Like: The 4 bits in the code then identify each of the nine regions as shown below. By observing the original smiley face closely, we can see that there are two blue lines which are represented as B1, B2 suutherland E1, E2 cohwn the above figure.
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. First the polygon is clipped against the left edge of coehn polygon window to get new vertices of the polygon.
If both codes arebitwise OR of the codes yields line lies completely inside the window: