Initial. Don't... just don't ask.

doc/man3/gl_triangle.3

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