Clipping in Computer Graphics
Clipping is a process of extracting portion or an object or image that is to be displayed on viewport. Also defined as procedure that identifies whether the portion of any graphics object is within or outside of a specified region or space.
The region or space against which an object is to be clipped is called a clip Window. Therefore, clipping_determines which elements of the picture or image lie inside the window and so are visible.
For an image or object there are three possibilities:
- The entire image is within the window and therefore entire image will display or visible.
- The entire image is outside the window and therefore the complete image will ignore and will not display or visible.
- An image is partially inside and partially outside the window. In such a case only the portion inside the window will display or visible.
The selection of the part of image which is inside the window and is to be displayed is done by some clipping_algorithm. There are several different applications that uses_clipping.
Some of the examples are:
- Extracting a part of a defined scene for viewing.
- Identifying visible surfaces in 3D views.
- Antialiasing line segments or object boundaries.
- Creating objects using solid modelling procedures.
- Displaying a multiwindow environment.
- Drawing and painting operations that allows parts of a picture to select for copying, moving, erasing, or duplicating.
- Depending upon the applications, the clip window can be a general polygon (rectangle) or it can even have curved boundaries.
Clipping_procedures or algorithm can applied to different primitives like point, lines, polygons etc. On the basis of these primitives, different types of clipping are:
The reverse of clipping known as shielding. Process of covering up a portion of picture or image that is not to select for displaying. Thus, shielding determines which elements of the picture lie outside the clipping_window and are not visible.