Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
gl_triangle(3)		      Svgalib User Manual		gl_triangle(3)

       gl_triangle - draw a triangle with interpolated colors

       #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);

       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

       If you are using	more than 8 bit	color, the z  values  will  be	inter-
       preted 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  com-

       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 threeD-
       kit/  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/  sub-
       directory. As of	this writing, svgalib-1.2.12.tar.gz is the latest ver-
       sion  and  can  be   retrieved	by   ftp   from   at
       /pub/Linux/libs/graphics	 and 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.

       vgagl(7),  svgalib(7), threedkit(7), gl_striangle(3), gl_swtriangle(3),
       gl_trigetcolorlookup(3),	   gl_trisetcolorlookup(3),	gl_trisetdraw-
       point(3), gl_wtriangle(3), plane(6), wrapdemo(6).

       This  manual page was edited by Michael Weller <eowmob@exp-math.uni-es->.	The demos, the initial documentation and the  whole  threedkit
       stuff was done by Paul Sheer <>.

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

       Donations  (by  check or	postal order) will be appreciated and will en-
       courage further development of this software. However this is  strictly
       on  a  voluntary	 basis where this software falls under the GNU LIBRARY

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


Want to link to this manual page? Use this URL:

home | help