Felisp
84436a5ae0
http://my.svgalib.org/svgalib/svgalib-1.9.25.tar.gz http://my.svgalib.org/svgalib/
105 lines
2.9 KiB
Groff
105 lines
2.9 KiB
Groff
.TH gl_triangle 3 "2 Aug 1997" "Svgalib (>= 1.2.11)" "Svgalib User Manual"
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.SH NAME
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gl_triangle \- draw a triangle with interpolated colors
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.SH SYNOPSIS
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.B #include <triangle.h>
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.BI "void gl_triangle(int " x0 ", int " y0 ", int " z0 ", int " x1 ", int " y1
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.BI ", int " z1 ", int " x2 ", int " y2 ", int " z2 ", int " bf );
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.SH DESCRIPTION
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Draws a triangle between the three points 0, 1 and 2.
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.IR z0 ", " z1 " and " z2
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are the colors at those points. Hence,
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if you set the palette to a grayscale, the triangle
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will have an interpolated gray shade.
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If you are using
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more than 8 bit color, the
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.I z
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values will be
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interpreted as an index to a lookup table of at most
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4096 entries long. Each entry is of type
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.BR long .
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You can set the entries with the function
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.BR gl_trisetcolorlookup (3).
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The
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.I bf
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value is used to tell the routine not to draw
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the triangle if it is facing the other way.
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.I bf
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tells
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which way the triangle should be facing to be drawn.
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since you will more than likely require both
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combinations.
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.IB bf " = 0"
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disables drawing when the points are arranged clockwise,
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.IB bf " = 1"
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disables drawing when the points are arranged counter clockwise.
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.IB bf " = -1"
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will probably always draw the triangle.
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Beware, these functions are not a direct part of the svgalib library.
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Instead their source is part of svgalib and can be found in the
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.I threeDkit/
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subdirectory of the original svgalib distribution. However, it is not
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installed in the system by default, s.t. it is unclear where you can find it
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if your svgalib was installed by some
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linux distribution.
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In case of any such problem, simply get an svgalib distribution from the net. Yo
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don't need to install it. Just
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.B make
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in the
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.I threeDkit/
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subdirectory. As of this writing,
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.I svgalib-1.2.12.tar.gz
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is the latest version and can be retrieved by ftp from
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.IR "sunsite.unc.edu" " at " "/pub/Linux/libs/graphics"
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and
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.IR "tsx-11.mit.edu" " at " "/pub/linux/sources/libs"
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which will most probably be mirrored by a site close to you.
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The functions are defined in the
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.IR tri.o " and " triangl.o
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files (or their resp. sources) which you must link to your program.
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.SH SEE ALSO
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.BR vgagl (7),
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.BR svgalib (7),
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.BR threedkit (7),
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.BR gl_striangle (3),
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.BR gl_swtriangle (3),
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.BR gl_trigetcolorlookup (3),
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.BR gl_trisetcolorlookup (3),
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.BR gl_trisetdrawpoint (3),
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.BR gl_wtriangle (3),
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.BR plane (6),
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.BR wrapdemo (6).
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.SH AUTHOR
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This manual page was edited by Michael Weller <eowmob@exp-math.uni-essen.de>. The
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demos, the initial documentation and the whole threedkit stuff was done by
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Paul Sheer <psheer@icon.co.za>.
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Paper mail:
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.RS
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Paul Sheer
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.br
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P O BOX 890507
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.br
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Lyndhurst
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.br
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Johannesburg 2106
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.br
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South Africa
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.RE
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Donations (by check or postal order) will be appreciated and will encourage
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further development of this software. However this is strictly on a voluntary
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basis where this software falls under the GNU LIBRARY GENERAL PUBLIC LICENSE.
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