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gl_wtriangle(3)		      Svgalib User Manual	       gl_wtriangle(3)

NAME
       gl_wtriangle - draw a shadowed pixmap mapped on a triangle

SYNOPSIS
       #include	<triangle.h>

       typedef struct {
	   unsigned char *bitmap1;
	   unsigned char *bitmap2;
	   int bf;
       } TD_tridata;

       void  gl_wtriangle(int  x0,  int	y0, int	xd0, int yd0, int z0 , int x1,
       int y1, int xd1,	int yd1, int z1	, int x2, int y2, int  xd2,  int  yd2,
       int z2, TD_tridata *tri);

DESCRIPTION
       Draws  a	 triangle  at points 0,	1, 2 by	mapping	the pixmaps defined in
       the TD_triangle structure into the triangle.

       The xd and yd values represent the triangle on the bitmap and the x and
       y  values  represent the	triangle on the	screen.	The z values represent
       an additional value which will be added to the color that is looked  up
       from the	pixmap data. Once again, if the	current	context	is more	than 8
       bits then the result is interpreted as an index to the same lookup  ta-
       ble. See	gl_triangle(3) for more	details	on shadowing.

       gl_wtriangle is used to draw wrapped surfaces with shadowing interpola-
       tion. The function gl_swtriangle(3) does	it without shadowing.

       bitmap1 defines the back	side of	the triangle, bitmap2 the front.

       The bf value is used to tell the	routine	to draw	the backside if	it  is
       facing the other	way.  bf tells which way the triangle should be	facing
       to show the front, since	you will more than likely require both	combi-
       nations.

       bf = 2 defines the back to be drawn when	the points are arranged	clock-
       wise, bf	= 3 defines the	back to	be drawn when the points are  arranged
       counter clockwise, bf = -1 will probably	always draw the	front.

       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	  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_triangle(3),	  gl_trigetcolorlookup(3),    gl_trisetcolorlookup(3),
       gl_trisetdrawpoint(3), plane(6),	wrapdemo(6).

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

       Paper mail:
	      Paul Sheer
	      P	O BOX 890507
	      Lyndhurst
	      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
       GENERAL PUBLIC LICENSE.

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

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | AUTHOR

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