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Mapping circuit of a CRT display device

  • US 4,974,177 A
  • Filed: 06/14/1989
  • Issued: 11/27/1990
  • Est. Priority Date: 10/04/1985
  • Status: Expired due to Fees
First Claim
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1. A CRT display device, used to display a representation of a three-dimensional polygon defined by data received from a host computer, said CRT display device comprising:

  • picture pattern storing means for storing a picture pattern and reference information for a two-dimensional polygon in a plane defined by an axis u and an axis v,a CRT display for displaying a two-dimensional representation of the three-dimensional polygon having vertexes with three-dimensional coordinates in a three-dimensional space defined by an axis x, an axis y and an axis z,vertex calculating means for calculating two dimensional coordinates of vertexes of said two-dimensional polygon from the data defining said three-dimensional polygon and the reference information for the two-dimensional polygon,inclination calculating means for calculating inclinations of line segments connecting adjacent vertexes of said three-dimensional polygon and inclinations of line segments connecting adjacent vertexes of said two-dimensional polygon, including;

    first increment calculating means for calculating increments parallel to the axis x and the axis z on the line segments connecting the adjacent vertexes of said three-dimensional polygon in response to increments parallel to the axis y, andsecond increment calculating means for calculating increments parallel to the axis u and the axis v on the line segments connecting the adjacent vertexes of said two-dimensional polygon, corresponding to the increments calculated by said first increment calculating means,vertexes interpolating means for performing interpolation between the adjacent vertexes of said three-dimensional polygon based on the three-dimensional coordinates of the vertexes of said three-dimensional polygon and the inclinations of the line segments therebetween, to produce first interpolated points, and for performing interpolation between the adjacent vertexes of said two-dimensional polygon based on the two-dimensional coordinates of the vertexes of said two-dimensional polygon and the inclinations of the line segments therebetween, to produce second interpolated points,start and end points interpolating means for performing interpolation between pairs of the first interpolated points on said three-dimensional polygon to produce third interpolated points and for performing interpolation between corresponding pairs of the second interpolated points on said two-dimensional polygon to produce fourth interpolated points, the first, second, third and fourth interpolated points having coordinates,reading means for reading, from said picture pattern storing means, the picture pattern at the coordinates of the fourth interpolated points within said two-dimensional polygon, anda frame memory, operatively connected to said reading means, said start and end points interpolating means and said CRT display, including storage areas corresponding to display areas of said CRT display for storing the picture pattern read out by said reading means using as addresses the coordinates of the third interpolated points.

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