US 5,668,940 AGranted

Method and apparatus for anti-aliasing polygon edges in a computer imaging system

AssigneeMartin Marietta Corporation

InventorsWalter Robert Steiner, Michael Leroy Morgan

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Abstract

The final viewable color of each pixel to be displayed from video data signal output of a computer image generator, is found by: using input data signals setting display space coordinates of each vertex of each face polygon to be displayed, to generate a crossing location of each polygon edge along an edge segment of any of the array of display pixels; storing, and then processing, the edge segment crossing data signals for all polygons affecting that pixel, along with color data for each of the faces occupying any portion of that pixel, and for a plurality of different edge segments of a constellation of four adjacent pixels, to obtain pixel color intensity data for each corner of each displayable pixel; and mixing polygon color intensity data signals for all corners of a presently-processed pixel, to determine the final, observable color of that display pixel.

Claims20

Dependent claims

A method for determining the final viewable color of each of an array of pixels to be displayed responsive to a video data signal output of a computer image generator, comprising the steps of:

(a) first receiving input data signals characterizing a set of display space (I,J) coordinates of each of at least three vertices of each of at least one face polygon to be displayed, each different pair of the vertices defining a different edge of the associated face polygon;
(b) generating, responsive to the received vertex data signals, a data signal describing a location of a crossing, if any, of each face polygon edge along an associated one of a plurality of edge segments bounding each pixel of the display pixel array;
(c) storing, on a per-pixel basis, the edge segment crossing data signals for all face polygons affecting that pixel, along with color data for each of the face polygons occupying any portion of that pixel;
(d) processing, for each pixel to be displayed, stored data for a plurality of different edge segments of a selected constellation of a plurality of adjacent pixels, to obtain a color intensity data signal for each corner of each displayable pixel;
and
(e) mixing color intensity data signals for all corners of a presently-processed pixel, to determine the final, observable color of that display pixel.

3 more elements

A color intensity subassembly for a display processor in a computer image generator (GIG), comprising:

edge interception calculator means, receiving input data signals characterizing a set of display space (I,J) coordinates for each of at least three vertices of each of a multiplicity of face polygons to be displayed, for determining (a) which edge segments, if any, of each of a sequential series of viewable display pixels are crossed by a polygon edge defined by each different pair of the received vertex data signals, and (b) a location of the crossing along the associated pixel edge segment;
frame buffer means for storing, on a per-pixel basis, the edge crossing data signals for all polygons affecting each pixel, along with color data for each of the face polygons occupying any portion of that pixel;
and
post processor means, receiving from the frame buffer means data signals characterizing, for each pixel to be displayed, a plurality of edge data signals for a constellation of a plurality of adjacent pixels, for resolving edge relationships and mixing polygon color intensity data to determine the final, observable color data signal for each pixel to be displayed by a display means receiving a video data output of the CIG.

1 more element

Dependencies are inferred from the claim text.