Date: 12 Jul 97 16:59:37 EDT
From: Wayne Davidson <100661 DOT 1576 AT CompuServe DOT COM>
To: "djgpp AT delorie DOT com" <djgpp AT delorie DOT com>
Subject: Help with Allegro 3d transformations
Message-ID: <970712205937_100661.1576_EHV51-1@CompuServe.COM>
Precedence: bulk

	I am realively new  to Allegro, as well as 3D graphics, and I am trying
to write a program that does 3d graphics, and I don't seem to get the right
results.  I call persp_project() and it returns numbers that seem way off the
wall, or is it that I am not using RHIDE correctly?. 
 Here is the code:
//Excuse me if this isn't the best looking code in the world.

//#include <conio.h>
#include <stdio.h>
#include "allegro.h"
//****************************
//structure that we might need
//****************************

//this one is a list of points
struct vertex_type
  {
     fix lx,   //local X
     ly,       //y
     lz,       //z
     wx,       //world x,  for after the transformations
     wy,       // y
     wz,       // z
     sx,       // x  //screen X and Y coordinates
     sy;       // y
  };
//******************************************************
//this one describes each face as indexes to vertex_type
//******************************************************
struct quad_type
  {
    int v1,v2,v3,v4;
  };

//*************************
//info about each data type
//*************************
class object_type
  {
    private:
    public:

     fix x,y,z;            //location
     fix rx,ry,rz;         //the angles for x,y,z axis

     fix d_x,d_y,d_z;      //where it is heading/how fast
     fix d_rx,d_ry,d_rz;   //rotation speed, and direction

     int num_vertices;     //we need the number of sides
     int num_faces;

     vertex_type *coords;        //pointer to the point defs
     quad_type *quads;           //pointer to the quad defs

     object_type(quad_type *quads1,vertex_type *coords1,int num_sides,int
num_points):
                 quads(quads1),
                 coords(coords1),
                 num_vertices(num_points),
                 num_faces(num_sides),
                 d_x(0),d_y(0),d_z(0),
                 d_rx(0),d_ry(0),d_rz(0),
                 rx(0),ry(0),rz(0){x=160;y=100;z=50;}
     void transform();
     void draw();			//I'm not sure if this works, as I have
not been able to test it.
  };

vertex_type points[] =                   /* a cube, centered on the origin */
{
   /* vertices of the cube */
   { -32, -32,-32,
      0,0,0,
      0,0},
   { -32,32,-32,
      0,0,0,
      0,0},
   {  32,32,-32,
       0,0,0,
       0,0},
   {  32, -32,-32,
      0,0,0,
      0,0},
   { -32,-32,32,
      0,0,0,
      0,0},
   { -32,32,32,
      0,0,0,
      0,0},
   {  32,32,32,
      0,0,0,
      0,0},
   {  32,-32,32,
      0,0,0,
      0,0},
};


quad_type faces[] =                   /* group the vertices into polygons */
{
   { 0, 3, 2, 1 },
   { 4, 5, 6, 7 },
   { 0, 1, 5, 4 },
   { 2, 3, 7, 6 },
   { 0, 4, 7, 3 },
   { 1, 2, 6, 5 }
};

//**********
//prototypes
//**********
void main (void);
//===============================================================================
==========
void main (void)
  {
    object_type cube (faces,points,6,8);
    allegro_init();
     //set my graphics mode
     if (set_gfx_mode (GFX_VGA, 320, 200, 0, 0) != 0)
         {
           printf ("error setting VGA 320x200x256\n");
           exit (1);
         }
     //if we make it this far, we are in graphics mode do what we want from here

     set_projection_viewport (0,0,320,200);
     cube.transform();
//     cube.draw();
  }

//*******************************************************************************
**
void object_type::transform()
  {
   MATRIX matrix;
  get_transformation_matrix (&matrix,(fix) 1,rx,ry,rz,x,y,z);
   vertex_type *c = coords;
   for (int i=0;i<num_vertices;i++,c++)
        {

          apply_matrix (&matrix,c->lx,c->ly,c->lz,
                        &c->wx,&c->wy,&c->wz);

          persp_project (c->wx,c->wy,c->wz,
                         &c->sx,&c->sy);  			//these are the
two varibles that don't seem right
        }

  }
//*******************************************************************************
**
void object_type::draw()
  {
     //simple wireframe for now, until understand more
     for (int i=0;i<num_faces;i++)
       {
          line (screen,(int)
coords[quads[i].v1].sx,(int)coords[quads[i].v1].sy,(int)coords[quads[i].v2].sx,(i
nt)coords[quads[i].v1].sy,2);
          line
(screen,(int)coords[quads[i].v2].sx,(int)coords[quads[i].v2].sy,(int)coords[quads
[i].v3].sx,(int)coords[quads[i].v1].sy,2);
          line
(screen,(int)coords[quads[i].v3].sx,(int)coords[quads[i].v3].sy,(int)coords[quads
[i].v4].sx,(int)coords[quads[i].v4].sy,2);
          line
(screen,(int)coords[quads[i].v1].sx,(int)coords[quads[i].v1].sy,(int)coords[quads
[i].v4].sx,(int)coords[quads[i].v4].sy,2);
       }

  }
//*******************************************************************************
**


Thanks in advance.
Joe Davidson
<100661 DOT 1576 AT compuserve DOT com>