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gl_triangle(3)                Svgalib User Manual               gl_triangle(3)

NAME
       gl_triangle - draw a triangle with interpolated colors

SYNOPSIS
       #include <triangle.h>

       void gl_triangle(int x0, int y0, int z0, int x1, int y1 , int z1, int
       x2, int y2, int z2, int bf);

DESCRIPTION
       Draws a triangle between the three points 0, 1 and 2.

       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 z values will be
       interpreted as an index to a lookup table of at most 4096 entries long.
       Each entry is of type long.

       You can set the entries with the function gl_trisetcolorlookup(3).

       The bf value is used to tell the routine not to draw the triangle if it
       is facing the other way.  bf tells which way the triangle should be
       facing to be drawn.  since you will more than likely require both
       combinations.

       bf = 0 disables drawing when the points are arranged clockwise, bf = 1
       disables drawing when the points are arranged counter clockwise.  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
       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 make in the threeDkit/
       subdirectory. As of this writing, svgalib-1.2.12.tar.gz is the latest
       version and can be retrieved by ftp from sunsite.unc.edu at
       /pub/Linux/libs/graphics and 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 tri.o and triangl.o files (or their
       resp. sources) which you must link to your program.

SEE ALSO
       vgagl(7), svgalib(7), threedkit(7), gl_striangle(3), gl_swtriangle(3),
       gl_trigetcolorlookup(3), gl_trisetcolorlookup(3),
       gl_trisetdrawpoint(3), gl_wtriangle(3), plane(6), wrapdemo(6).

AUTHOR
       This manual page was edited by Michael Weller <[email protected]
       essen.de>. The demos, the initial documentation and the whole threedkit
       stuff was done by Paul Sheer <[email protected]>.

       Paper mail:
              Paul Sheer
              P O BOX 890507
              Lyndhurst
              Johannesburg 2106
              South Africa

       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.

Svgalib (>= 1.2.11)               2 Aug 1997                    gl_triangle(3)
Command Section