CLIPPING OPERATIONS
CLIPPING
Generally, any procedure that identifies those portions of an image that are either inside or outside of a specified region of space is brought up as a clipping algorithm, or just clipping. The region against which an object is to clip is named a clip window. Applications of clipping include extracting a part of a detained scene for viewing; identifying visible surfaces in three-dimensiona1 views; anti aliasing line segments or object boundaries; creating objects using solid-modeling procedures; displaying a multi window environment; and drawing and painting operations that allow parts of an image to be selected for copying, moving, erasing, or duplicating. betting on the applying, the clip window will be a general polygon or it can even have curved boundaries. We first consider clipping methods using rectangular clip regions, then we discuss methods for other clip region shapes.
For the viewing transformation, we would like to display only those picture parts that are within the window area (assuming that the clipping flags haven't been set to no clip). Everything outside the window is discarded. Clipping algorithms will be applied in world coordinates, so only the contents of the window interior are mapped to device coordinates. Alternatively, the whole world-coordinate picture will be mapped first to device coordinates, or normalized device coordinates, then clipped against the viewport boundaries. World-coordinate clipping removes those primitives outside the window from further consideration, thus eliminating the processing necessary to remodel those primitives to device space. Viewport clipping, on the opposite hand, can reduce calculations by al- lowing concatenation of viewing and geometric transformation matrices. But viewport clipping does require that the transformation to device coordinates be performed for all objects, including those outside the window area. On raster systems, clipping algorithms are often combined with scan conversion. within the following sections, we consider algorithms for clipping the subsequent primitive types
Point Clipping
Line Clipping (straight-line segments)
Area Clipping (polygons)
Curve Clipping Text Clipping
Line and polygon clipping routines are standard components of graphics packages, but many packages accommodate curved objects, particularly spline curves and conics, like circles and ellipses. in our own way to handle curved objects is to approximate them with straight-line segments and apply the line- or polygon- clipping procedure.
PROGRAM -- CLICK HERE!!
Generally, any procedure that identifies those portions of an image that are either inside or outside of a specified region of space is brought up as a clipping algorithm, or just clipping. The region against which an object is to clip is named a clip window. Applications of clipping include extracting a part of a detained scene for viewing; identifying visible surfaces in three-dimensiona1 views; anti aliasing line segments or object boundaries; creating objects using solid-modeling procedures; displaying a multi window environment; and drawing and painting operations that allow parts of an image to be selected for copying, moving, erasing, or duplicating. betting on the applying, the clip window will be a general polygon or it can even have curved boundaries. We first consider clipping methods using rectangular clip regions, then we discuss methods for other clip region shapes.
For the viewing transformation, we would like to display only those picture parts that are within the window area (assuming that the clipping flags haven't been set to no clip). Everything outside the window is discarded. Clipping algorithms will be applied in world coordinates, so only the contents of the window interior are mapped to device coordinates. Alternatively, the whole world-coordinate picture will be mapped first to device coordinates, or normalized device coordinates, then clipped against the viewport boundaries. World-coordinate clipping removes those primitives outside the window from further consideration, thus eliminating the processing necessary to remodel those primitives to device space. Viewport clipping, on the opposite hand, can reduce calculations by al- lowing concatenation of viewing and geometric transformation matrices. But viewport clipping does require that the transformation to device coordinates be performed for all objects, including those outside the window area. On raster systems, clipping algorithms are often combined with scan conversion. within the following sections, we consider algorithms for clipping the subsequent primitive types
Point Clipping
Line Clipping (straight-line segments)
Area Clipping (polygons)
Curve Clipping Text Clipping
Line and polygon clipping routines are standard components of graphics packages, but many packages accommodate curved objects, particularly spline curves and conics, like circles and ellipses. in our own way to handle curved objects is to approximate them with straight-line segments and apply the line- or polygon- clipping procedure.
PROGRAM -- CLICK HERE!!
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