From: Shawn Hargreaves <Shawn AT talula DOT demon DOT co DOT uk>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Allegros quad3d function HELP NEEDED.   PLEASE ;-)
Date: Sat, 15 Mar 1997 15:33:45 +0000
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References: <tQhk9AA8R4HzEwpx AT jenkinsdavid DOT demon DOT co DOT uk>
 <or1VzBAaUjKzEwS2 AT jenkinsdavid DOT demon DOT co DOT uk>
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David Jenkins writes:
>Could somebody send me 2 source files.
>1-With just one simple quad3d() face drawn on the screen.
>
>No rotation or anything just the most SIMPLE way to get a quad3d face
>drawn onto a screen.

Here's a really basic quad drawer. You might also want to have a look at
the excellent 3d tutorial by Tero Parvinen, which can be found on 
http://www.niksula.cs.hut.fi/~tparvine/allegro3d/.


#include <allegro.h>

int main()
{
   /* Declare four vertices defining the corners of the quad. In a real
    * program these would of course be calculated on the fly, rather 
    * than hard-coded like this...
    *
    * The X and Y values are the position of the point in 2d screen 
    * space. Z is only important if you are doing perspective-correct 
    * texture mapping. The U and V coordinates are also for texture 
    * mapping, and the color means exactly what you would think :-)
    */
                /* x    y    z    u    v    color */
   V3D_f vtx1 = {  10,  10,  0,   0,   0,   255   };
   V3D_f vtx2 = {  150, 40,  0,   0,   0,   10    };
   V3D_f vtx3 = {  100, 120, 0,   0,   0,   128   };
   V3D_f vtx4 = {  40,  140, 0,   0,   0,   160   };

   PALLETE pal;
   int i;

   allegro_init();
   install_keyboard();
   set_gfx_mode(GFX_VGA, 320, 200, 0, 0);

   /* make a greyscale (black -> white) gradient in the palette. This is
    * needed for the GCOL drawing mode (if you want to do gouraud 
    * shading without having any gradients in the palette, set up an 
    * rgb_map table and use GRGB mode instead).
    */
   for (i=0; i<256; i++)
      pal[i].r = pal[i].g = pal[i].b = i/4;

   set_palette(pal);

   /* draw a flat-shaded quad */
   quad3d_f(screen, POLYTYPE_FLAT, NULL, &vtx1, &vtx2, &vtx3, &vtx4);
   readkey();

   /* draw a gouraud-shaded quad */
   quad3d_f(screen, POLYTYPE_GCOL, NULL, &vtx1, &vtx2, &vtx3, &vtx4);
   readkey();

   return 0;
}



/*
 *  Shawn Hargreaves - shawn AT talula DOT demon DOT co DOT uk - http://www.talula.demon.co.uk/
 *  Beauty is a French phonetic corruption of a short cloth neck ornament.
 */