Method for generating an ellipse with texture and perspective
First Claim
1. A computerized method for generating a line in two or more space dimensions, on a graphics display having a pixel matrix, each pixel being addressed by two-dimensional screen coordinates, said graphics display having a color palette, said pixels storing color values for the purpose of selecting a specified color from said color palette, said method comprising the steps of:
- (a) determining two X and Y view factors for said graphics display screen as a function of said pixel matrix dimensions and a perspective field of view;
(b) deriving a depth constant from said X and Y view factors, said depth constant being a binary number;
translating a known starting point on said line to a screen point using said perspective field of view, said starting point being defined in X, Y and Z space, and said screen point having X and Y coordinates on said graphics display;
means for obtaining a series of X, Y and Z step movements along said line;
transforming said X and Y step movements along said line into perspective by incrementing or decrementing said X and Y screen point coordinates;
transforming said Z step movements along said line into perspective by employing a depth rescaling ratio, said depth rescaling ratio being based on said depth constant.
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Abstract
A method for generating a circular or elliptical arc on a digital computer display (FIG. 1). An ellipse can be generated in two dimensions (FIG. 5) or three dimensions with perspective (FIG. 13). The ellipse dimensions form angle meters (FIG. 4) that provide rotational angle information for a screen point moving along the elliptical curve (FIG. 3). Pixels are colored and antialiased with a texture table (FIG. 2). The drawing loops for two dimensions (FIG. 6) and three dimensions (FIG. 14) are computationally simple and suitable for implementation in a custom designed, dedicated computer circuit. The three dimensional perspective drawing employs a depth constant that fits the curve to the perspective field of view (FIG. 8). As the curve depth changes, the depth constant directs the rescaling of the ellipse (FIG. 11).
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Citations
10 Claims
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1. A computerized method for generating a line in two or more space dimensions, on a graphics display having a pixel matrix, each pixel being addressed by two-dimensional screen coordinates, said graphics display having a color palette, said pixels storing color values for the purpose of selecting a specified color from said color palette, said method comprising the steps of:
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(a) determining two X and Y view factors for said graphics display screen as a function of said pixel matrix dimensions and a perspective field of view; (b) deriving a depth constant from said X and Y view factors, said depth constant being a binary number; translating a known starting point on said line to a screen point using said perspective field of view, said starting point being defined in X, Y and Z space, and said screen point having X and Y coordinates on said graphics display; means for obtaining a series of X, Y and Z step movements along said line; transforming said X and Y step movements along said line into perspective by incrementing or decrementing said X and Y screen point coordinates; transforming said Z step movements along said line into perspective by employing a depth rescaling ratio, said depth rescaling ratio being based on said depth constant. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification