/****************************************************************************
*                ray.c
*
*  This module implements the code pertaining to rays.
*
*  from Persistence of Vision Raytracer 
*  Copyright 1992 Persistence of Vision Team
*---------------------------------------------------------------------------
*  Copying, distribution and legal info is in the file povlegal.doc which
*  should be distributed with this file. If povlegal.doc is not available
*  or for more info please contact:
*
*       Drew Wells [POV-Team Leader] 
*       CIS: 73767,1244  Internet: 73767.1244@compuserve.com
*       Phone: (213) 254-4041
* 
* This program is based on the popular DKB raytracer version 2.12.
* DKBTrace was originally written by David K. Buck.
* DKBTrace Ver 2.0-2.12 were written by David K. Buck & Aaron A. Collins.
*
*****************************************************************************/



#include "frame.h"
#include "vector.h"
#include "povproto.h"

#define Mix(a,b,c) { \
(a).x = (b).x * (c).y; \
   (a).y = (b).x * (c).z; \
   (a).z = (b).y * (c).z; }

void Make_Ray(r)
RAY *r;
{
VECTOR Temp_Init_Dir;

VSquareTerms (r -> Initial_2, r -> Initial);
VSquareTerms (r -> Direction_2, r -> Direction);
VEvaluate (r -> Initial_Direction, r -> Initial, r -> Direction);
Mix (r -> Mixed_Initial_Initial, r -> Initial, r -> Initial);
Mix (r -> Mixed_Dir_Dir, r -> Direction, r -> Direction);
Mix (Temp_Init_Dir, r -> Initial, r -> Direction);
Mix (r -> Mixed_Init_Dir, r -> Direction, r -> Initial);
VAdd (r -> Mixed_Init_Dir, r -> Mixed_Init_Dir, Temp_Init_Dir);
r -> Quadric_Constants_Cached = TRUE;
}

void Initialize_Ray_Containers (Ray)
RAY *Ray;
{
Ray -> Containing_Index = -1;
}

void Copy_Ray_Containers (Dest_Ray, Source_Ray)
RAY *Dest_Ray, *Source_Ray;
{
register int i;

if ((Dest_Ray -> Containing_Index = Source_Ray -> Containing_Index)
>= MAX_CONTAINING_OBJECTS) {
   fprintf (stderr, "ERROR - Containing Index too high\n");
   close_all();
   exit (1);
}

for (i = 0 ; i < MAX_CONTAINING_OBJECTS ; i++) {
   Dest_Ray -> Containing_Textures[i] = Source_Ray -> Containing_Textures[i];
   Dest_Ray -> Containing_IORs[i] = Source_Ray -> Containing_IORs[i];
}
}

void Ray_Enter (ray, texture)
RAY *ray;
TEXTURE *texture;
{
register int index;

if ((index = ++(ray -> Containing_Index)) >= MAX_CONTAINING_OBJECTS) {
   fprintf (stderr, "Too many nested refracting objects\n");
   close_all();
   exit(1);
}

ray -> Containing_Textures [index] = texture;
ray -> Containing_IORs [index] = texture->Object_Index_Of_Refraction;
}

void Ray_Exit (ray)
RAY *ray;
{
if (--(ray -> Containing_Index) < -1) {
   fprintf (stderr, "Too many exits from refractions\n");
   close_all();
   exit(1);
}
}