Man

Command Section
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
       table. See gl_triangle(3) for more details on shadowing.

       gl_wtriangle is used to draw wrapped surfaces with shadowing
       interpolation. 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
       combinations.

       bf = 2 defines the back to be drawn when the points are arranged
       clockwise, 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
       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_triangle(3), gl_trigetcolorlookup(3), gl_trisetcolorlookup(3),
       gl_trisetdrawpoint(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_wtriangle(3)
Command Section