67 lines
1.8 KiB
Groff
67 lines
1.8 KiB
Groff
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.TH gl_bcircle 3 "4 Dec 1999" "Svgalib (>= 1.4.1)" "Svgalib User Manual"
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.SH NAME
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gl_bcircle \- draw a filled or unfilled Bresenham circle
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.SH SYNOPSIS
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.B #include <vgagl.h>
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.BI "void gl_bcircle(int " x ", int " y ", int " r ", int " c ", int " fill ");"
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.SH DESCRIPTION
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Draw a Bresenham circle of radius
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.I r
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in color
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.I c ,
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centered at
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.I ( x ", " y ).
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.I Fill
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should be 0 for a hollow circle, or any other value for a solid color.
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This function differs from gl_circle (3) and gl_fillcircle (3) in that it
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looks good in 320 x 200 screen modes. The modified algorithm was provided
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by Chris Atenasio <chris@svgalib.org>, and is based upon Bresenham's
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formula.
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Note that the "circle" is technically an ellipse, and is actually wider
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than it is tall. Therefore,
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.I r
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is equal to the circle's height, but is less than its width. This
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distortion is necessary to accomodate the 8:5 aspect ratio (e.g., 320 x
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200).
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I don't recommend using this function in standard 4:3 screen modes (e.g.,
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640 x 480 and higher). Furthermore, care must be taken so that a circle
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drawn with this function isn't copied to a screen with a different aspect
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ratio. Otherwise, the result may be undesirable.
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.SH SEE ALSO
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.BR svgalib (7),
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.BR vgagl (7),
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.BR svgalib.conf (5),
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.BR threedkit (7),
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.BR testgl (1),
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.BR plane (1),
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.BR wrapdemo (1),
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.BR gl_circle (3),
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.BR gl_clearscreen (3),
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.BR gl_colorfont (3),
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.BR gl_disableclipping (3),
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.BR gl_enableclipping (3),
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.BR gl_fillbox (3),
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.BR gl_fillcircle (3),
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.BR gl_hline (3),
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.BR gl_line (3),
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.BR gl_setclippingwindow (3),
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.BR gl_setpalette (3),
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.BR gl_setpalettecolor (3),
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.BR gl_setpalettecolors (3),
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.BR gl_setpixel (3),
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.BR gl_setpixelrgb (3),
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.BR gl_setrgbpalette (3),
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.BR gl_setwritemode (3).
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.SH AUTHOR
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This manual page was written by Jay Link <jlink@svgalib.org>.
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