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US 6,271,862 B1Granted
Apparatus and method for determining line clipping intersection points
AssigneeSeiko Epson Corporation
InventorCindy Z. Yu
Life of this patent
Estimating the term…
Abstract
In a graphics system, an apparatus and method reduce the computational complexity for clipping in a graphics environment by determining the relationship between a line and a graphics element, and performing an optimized number of calculations based on the determined relationship. More specifically, it is first determined whether a clipping operation must be performed at all. This is done by forming a rectangle using the line as a diagonal and comparing that rectangle to the graphics element area to determine overlap. If there is no overlap, no clipping needs to be performed. If there is overlap, the overlapping area is determined and categorized, and a corresponding clipping operation is then performed.
Claims24
Apparatus for clipping a graphics element, comprising:
- means for comparing a logical rectangle formed based on the graphics element with a rectangle defining a graphics area to determine whether the graphics element and the graphics area overlap;
- means for determining the need for a clipping operation according to the determination whether the logical rectangle and graphics area rectangle overlap;
- means for categorizing the overlap between the logical rectangle and the graphics area rectangle if there is a need for clipping, the categorizing including finding an overlapping region, determining each common edge of the graphics area rectangle and the overlapping region, and determining intersection clipping points between the graphics element and the graphics area based on the common edge determination;
- and
- means for clipping the graphics element based on the categorization of the overlap.
2 more elements
A method for clipping a graphics element, comprising:
- comparing a logical rectangle formed based on the graphics element with a rectangle defining graphics area to determine whether the graphics element and the graphics area overlap;
- determining the need for a clipping operation according to the determination whether the logical rectangle and graphics area rectangle overlap;
- categorizing the overlap between the logical rectangle and the graphics area rectangle if there is a need for clipping, the categorizing including finding an overlapping region, determining each common edge of the graphics area rectangle and the overlapping region, and determining intersection clipping points between the graphics element and the graphics area based on the common edge determination;
- and
- clipping the graphics element based on the categorization of the overlap.
2 more elements
A system for performing clipping of a graphics element, comprising:
- means for providing a first graphics command requesting that a graphics element be written to a display device, and for providing a second graphics command requesting that a graphics area be written to the display device;
- means for comparing a logical rectangle formed based on the graphics element with rectangle defining the graphics area to determine whether the graphics element and graphics area overlap;
- means for determining the need for a clipping operation according to the determination whether the logical rectangle and graphics area rectangle overlap;
- means for categorizing the overlap between the logical rectangle and the graphics area rectangle if there is a need for clipping the categorizing including finding an overlapping region, determining each common edge of the graphics area rectangle and the overlapping region, and determining intersection clipping points between the graphics element and the graphics area based on the common edge determination;
- and
- means for clipping the graphics element based on the categorization of the overlap.
3 more elements
A computer-readable medium containing instructions to perform a method for clipping a graphics element, the method comprising:
- comparing a logical rectangle formed based on the graphics element with a rectangle defining a graphics area to determine whether the graphics element and the graphics area overlap;
- determining the need for a clipping operation according to the determination whether the logical rectangle and graphics area rectangle overlap;
- categorizing the overlap between the logical rectangle and the graphics area rectangle if there is a need for clipping, the categorizing including finding an overlapping region, determining each common edge of the graphics area rectangle and the overlapping region, and determining intersection clipping points between the graphics element and the graphics area based on the common edge determination;
- and
- clipping the graphics element based on the categorization of the overlap.
2 more elements
Apparatus for clipping a graphics element, comprising:
- a comparator for comparing a logical rectangle formed based on the graphics element with a rectangle defining a graphics area to determine whether the graphics element and the graphics area overlap;
- a determiner for determining the need for a clipping operation according to the determination whether the logical rectangle and graphics area rectangle overlap;
- a categorizer for categorizing the overlap between the logical rectangle and the graphics area rectangle if there is a need for clipping, the categorizing including finding an overlapping region, determining each common edge of the graphics area rectangle and the overlapping region, and determining intersection clipping points between the graphics element and the graphics area based on the common edge determination;
- and
- a clipper for clipping the graphics element based on the categorization of the overlap.
2 more elements
A signal containing instructions to perform a method for clipping a graphics element, the method comprising:
- comparing a logical rectangle formed based on the graphics element with a rectangle defining a graphics area to determine whether the graphics element and the graphics area overlap;
- determining the need for a clipping operation according to the determination whether the logical rectangle and graphics area rectangle overlap;
- categorizing the overlap between the logical rectangle and the graphics area rectangle if there is a need for clipping, the categorizing including finding an overlapping region, determining each common edge of the graphics area rectangle and the overlapping region, and determining intersection clipping points between the graphics element and the graphics area based on the common edge determination;
- and
- clipping the graphics element based on the categorization of the overlap.
2 more elements
Dependencies are inferred from the claim text.