US 5,471,568 AGranted

Object-oriented apparatus and method for scan line conversion of graphic edges

AssigneeTaligent, Inc.

InventorsRichard D. Webb, Arthur W. Cabral

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Abstract

An object-oriented graphic system performs a scan conversion process on a geometric figure with edges. The figure is represented by a graphic object which contains data describing the edges and a method for traversing the edges to outline the figure. The scan conversion is performed by loading the graphic object into a memory and using the graphic object data and methods to generate a plurality of edge objects, each of which represents one of the edges. The edge objects are then manipulated by means of an edge engine object to generate a plurality of scan lines of varying numbers of pixels which scan lines together fill or frame the geometric figure and complete the scan conversion. The geometric figure can be displayed by displaying the pixels in the scan lines.

Claims19

Dependent claims

An object-oriented method for scan converting a closed geometric figure having a plurality of edges into a plurality of scan line pixels, the method operating in a computer system having a memory, wherein the geometric figure is represented by a graphic object which is comprised of data describing the plurality of edges and an object function for traversing the plurality of edges to outline the figure, the method comprising the steps of:

(a) loading the graphic object into the memory;
(b) creating a plurality of edge objects each of which edge objects comprises edge data describing a predetermined edge shape and an edge function for moving along the predetermined edge shape, utilizing the steps of:
(b1) selecting a single name for the plurality of edge objects;
(b2) assigning the selected name to each of the plurality of edge objects;
and
(b3) assigning different parameters to each of the plurality of edge objects;
(c) accessing the graphic object and utilizing the data and the object function therein to select ones of the plurality of edge objects to represent the edges;
(d) creating an edge engine object comprising a plurality of scan line functions for identifying portions of scan lines which lie within the geometric figure and on the edges;
and
(e) using the edge engine object scan line functions and the selected ones of the plurality of edge objects to generate a plurality of scan line pixels corresponding to identified portions of scan lines.

7 more elements

An apparatus for scan converting a closed geometric figure having a plurality of edges into a plurality of scan line pixels, wherein the geometric figure is represented by a graphic object which is comprised of data describing the plurality of edges and an object function for traversing the plurality of edges to outline the figure, the apparatus comprising:

(a) a processor;
(b) a memory;
(c) means controlled by the processor for loading the graphic object into the memory;
(d) means controlled by the processor for creating and storing a plurality of edge objects in the memory, each of which edge objects comprises edge data describing a predetermined edge shape and an edge function for moving along the predetermined edge shape;
wherein the creating means comprises means for assigning a single name to each of the plurality of edge objects;
and means for assigning different parameters to each of the plurality of edge objects;
(e) means responsive to the data and the object function in the graphic object for selecting ones of the plurality of edge objects to represent the edges;
and
(f) an edge engine object responsive to the selected ones of the plurality of edge objects for generating a plurality of scan line pixels which lie within the geometric figure and on the edges.

6 more elements

Dependencies are inferred from the claim text.