1gl_triangle(3)                Svgalib User Manual               gl_triangle(3)
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NAME

6       gl_triangle - draw a triangle with interpolated colors
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SYNOPSIS

10       #include <triangle.h>
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12       void  gl_triangle(int  x0, int y0, int z0, int x1, int y1 , int z1, int
13       x2, int y2, int z2, int bf);
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DESCRIPTION

17       Draws a triangle between the three points 0, 1 and 2.
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19       z0, z1 and z2 are the colors at those points. Hence,  if  you  set  the
20       palette  to  a  grayscale,  the triangle will have an interpolated gray
21       shade.
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23       If you are using more than 8 bit color, the z  values  will  be  inter‐
24       preted as an index to a lookup table of at most 4096 entries long. Each
25       entry is of type long.
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27       You can set the entries with the function gl_trisetcolorlookup(3).
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29       The bf value is used to tell the routine not to draw the triangle if it
30       is  facing  the  other  way.  bf tells which way the triangle should be
31       facing to be drawn.  since you will more than likely require both  com‐
32       binations.
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34       bf  = 0 disables drawing when the points are arranged clockwise, bf = 1
35       disables drawing when the points are arranged counter clockwise.  bf  =
36       -1 will probably always draw the triangle.
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38       Beware,  these  functions are not a direct part of the svgalib library.
39       Instead their source is part of svgalib and can be found in the threeD‐
40       kit/  subdirectory of the original svgalib distribution. However, it is
41       not installed in the system by default, s.t. it is  unclear  where  you
42       can find it if your svgalib was installed by some linux distribution.
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44       In  case  of  any such problem, simply get an svgalib distribution from
45       the net. Yo don't need to install it. Just make in the threeDkit/  sub‐
46       directory. As of this writing, svgalib-1.2.12.tar.gz is the latest ver‐
47       sion  and  can  be   retrieved   by   ftp   from   sunsite.unc.edu   at
48       /pub/Linux/libs/graphics  and tsx-11.mit.edu at /pub/linux/sources/libs
49       which will most probably be mirrored by a site close to you.
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51       The functions are defined in the tri.o and triangl.o  files  (or  their
52       resp. sources) which you must link to your program.
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SEE ALSO

56       vgagl(7),  svgalib(7), threedkit(7), gl_striangle(3), gl_swtriangle(3),
57       gl_trigetcolorlookup(3),    gl_trisetcolorlookup(3),     gl_trisetdraw‐
58       point(3), gl_wtriangle(3), plane(6), wrapdemo(6).
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AUTHOR

62       This  manual  page  was  edited by Michael Weller <eowmob@exp-math.uni-
63       essen.de>. The demos, the initial documentation and the whole threedkit
64       stuff was done by Paul Sheer <psheer@icon.co.za>.
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66       Paper mail:
67              Paul Sheer
68              P O BOX 890507
69              Lyndhurst
70              Johannesburg 2106
71              South Africa
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73       Donations  (by  check  or  postal  order)  will be appreciated and will
74       encourage  further  development  of  this  software.  However  this  is
75       strictly  on  a voluntary basis where this software falls under the GNU
76       LIBRARY GENERAL PUBLIC LICENSE.
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80Svgalib (>= 1.2.11)               2 Aug 1997                    gl_triangle(3)
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