/****************************************************************************
*                planes.c
*
*  This module implements functions that manipulate planes.
*
*  from Persistence of Vision(tm) Ray Tracer
*  Copyright 1996 Persistence of Vision Team
*---------------------------------------------------------------------------
*  NOTICE: This source code file is provided so that users may experiment
*  with enhancements to POV-Ray and to port the software to platforms other
*  than those supported by the POV-Ray Team.  There are strict rules under
*  which you are permitted to use this file.  The rules are in the file
*  named POVLEGAL.DOC which should be distributed with this file. If
*  POVLEGAL.DOC is not available or for more info please contact the POV-Ray
*  Team Coordinator by leaving a message in CompuServe's Graphics Developer's
*  Forum.  The latest version of POV-Ray may be found there as well.
*
* 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 "povray.h"
#include "vector.h"
#include "povproto.h"
#include "matrices.h"
#include "objects.h"
#include "planes.h"



/*****************************************************************************
* Local preprocessor defines
******************************************************************************/

#define DEPTH_TOLERANCE 1.0e-6

/*****************************************************************************
* Static functions
******************************************************************************/

static int   Intersect_Plane PARAMS((RAY *Ray, PLANE *Plane, DBL *Depth));
static int   All_Plane_Intersections PARAMS((OBJECT *Object, RAY *Ray, ISTACK *Depth_Stack));
static int   Inside_Plane PARAMS((VECTOR point, OBJECT *Object));
static void  Plane_Normal PARAMS((VECTOR Result, OBJECT *Object, INTERSECTION *Inter));
static void  *Copy_Plane PARAMS((OBJECT *Object));
static void  Translate_Plane PARAMS((OBJECT *Object, VECTOR Vector, TRANSFORM *Trans));
static void  Rotate_Plane PARAMS((OBJECT *Object, VECTOR Vector, TRANSFORM *Trans));
static void  Scale_Plane PARAMS((OBJECT *Object, VECTOR Vector, TRANSFORM *Trans));
static void  Transform_Plane PARAMS((OBJECT *Object, TRANSFORM *Trans));
static void  Invert_Plane PARAMS((OBJECT *Object));
static void  Destroy_Plane PARAMS((OBJECT *Object));

/*****************************************************************************
* Local variables
******************************************************************************/

METHODS Plane_Methods =
{
  All_Plane_Intersections,
  Inside_Plane, Plane_Normal,
  Copy_Plane,
  Translate_Plane, Rotate_Plane,
  Scale_Plane, Transform_Plane, Invert_Plane, Destroy_Plane
};


/*****************************************************************************
*
* FUNCTION
*
*   All_Plane_Intersections
*
* INPUT
*   
* OUTPUT
*   
* RETURNS
*   
* AUTHOR
*
*   POV-Ray Team
*   
* DESCRIPTION
*
*   -
*
* CHANGES
*
*   -
*
******************************************************************************/

static int All_Plane_Intersections (Object, Ray, Depth_Stack)
OBJECT *Object;
RAY *Ray;
ISTACK *Depth_Stack;
{
  DBL Depth;
  VECTOR IPoint;

  if (Intersect_Plane(Ray, (PLANE *)Object, &Depth))
  {
    VEvaluateRay(IPoint, Ray->Initial, Depth, Ray->Direction);

    if (Point_In_Clip(IPoint, Object->Clip))
    {
      push_entry(Depth,IPoint,Object,Depth_Stack);

      return(TRUE);
    }
  }

  return(FALSE);
}



/*****************************************************************************
*
* FUNCTION
*
*   Intersect_Plane
*
* INPUT
*   
* OUTPUT
*   
* RETURNS
*   
* AUTHOR
*
*   POV-Ray Team
*   
* DESCRIPTION
*
*   -
*
* CHANGES
*
*   -
*
******************************************************************************/

static int Intersect_Plane (Ray, Plane, Depth)
RAY *Ray;
PLANE *Plane;
DBL *Depth;
{
  DBL NormalDotOrigin, NormalDotDirection;
  VECTOR P, D;

  Increase_Counter(stats[Ray_Plane_Tests]);

  if (Plane->Trans == NULL)
  {
    VDot(NormalDotDirection, Plane->Normal_Vector, Ray->Direction);

    if (fabs(NormalDotDirection) < EPSILON)
    {
      return(FALSE);
    }

    VDot(NormalDotOrigin, Plane->Normal_Vector, Ray->Initial);
  }
  else
  {
    MInvTransPoint(P, Ray->Initial, Plane->Trans);
    MInvTransDirection(D, Ray->Direction, Plane->Trans);

    VDot(NormalDotDirection, Plane->Normal_Vector, D);

    if (fabs(NormalDotDirection) < EPSILON)
    {
      return(FALSE);
    }

    VDot(NormalDotOrigin, Plane->Normal_Vector, P);
  }

  *Depth = -(NormalDotOrigin + Plane->Distance) / NormalDotDirection;

  if ((*Depth >= DEPTH_TOLERANCE) && (*Depth <= Max_Distance))
  {
    Increase_Counter(stats[Ray_Plane_Tests_Succeeded]);

    return (TRUE);
  }
  else
  {
    return (FALSE);
  }
}



/*****************************************************************************
*
* FUNCTION
*
*   Inside_Plane
*
* INPUT
*   
* OUTPUT
*   
* RETURNS
*   
* AUTHOR
*
*   POV-Ray Team
*   
* DESCRIPTION
*
*   -
*
* CHANGES
*
*   -
*
******************************************************************************/

static int Inside_Plane (IPoint, Object)
VECTOR IPoint;
OBJECT *Object;
{
  DBL Temp;
  VECTOR P;

  if (((PLANE *)Object)->Trans == NULL)
  {
    VDot (Temp, IPoint, ((PLANE *)Object)->Normal_Vector);
  }
  else
  {
    MInvTransPoint(P, IPoint, ((PLANE *)Object)->Trans);

    VDot (Temp, P, ((PLANE *)Object)->Normal_Vector);
  }

  return((Temp + ((PLANE *)Object)->Distance) < EPSILON);
}



/*****************************************************************************
*
* FUNCTION
*
*   Plane_Normal
*
* INPUT
*
* OUTPUT
*
* RETURNS
*
* AUTHOR
*
*   POV-Ray Team
*
* DESCRIPTION
*
*   -
*
* CHANGES
*
*   -
*
******************************************************************************/

static void Plane_Normal (Result, Object, Inter)
OBJECT *Object;
VECTOR Result;
INTERSECTION *Inter;
{
  Assign_Vector(Result,((PLANE *)Object)->Normal_Vector);

  if (((PLANE *)Object)->Trans != NULL)
  {
    MTransNormal(Result, Result, ((PLANE *)Object)->Trans);

    VNormalize(Result, Result);
  }
}



/*****************************************************************************
*
* FUNCTION
*
*   Translate_Plane
*
* INPUT
*   
* OUTPUT
*   
* RETURNS
*   
* AUTHOR
*
*   POV-Ray Team
*   
* DESCRIPTION
*
*   -
*
* CHANGES
*
*   -
*
******************************************************************************/

static void Translate_Plane (Object, Vector, Trans)
OBJECT *Object;
VECTOR Vector;
TRANSFORM *Trans;
{
  VECTOR Translation;
  PLANE *Plane = (PLANE *)Object;

  if (Plane->Trans == NULL)
  {
    VEvaluate (Translation, ((PLANE *)Object)->Normal_Vector, Vector);

    ((PLANE *)Object)->Distance -= Translation[X] + Translation[Y] + Translation[Z];

    Compute_Plane_BBox((PLANE *)Object);
  }
  else
  {
    Transform_Plane(Object, Trans);
  }
}



/*****************************************************************************
*
* FUNCTION
*
*   Rotate_Plane
*
* INPUT
*   
* OUTPUT
*   
* RETURNS
*   
* AUTHOR
*
*   POV-Ray Team
*   
* DESCRIPTION
*
*   -
*
* CHANGES
*
*   -
*
******************************************************************************/

static void Rotate_Plane (Object, Vector, Trans)
OBJECT *Object;
VECTOR Vector;
TRANSFORM *Trans;
{
  if (((PLANE *)Object)->Trans == NULL)
  {
    MTransDirection(((PLANE *)Object)->Normal_Vector, ((PLANE *)Object)->Normal_Vector, Trans);

    Compute_Plane_BBox(((PLANE *)Object));
  }
  else
  {
    Transform_Plane (Object, Trans);
  }
}



/*****************************************************************************
*
* FUNCTION
*
*   Scale_Plane
*
* INPUT
*   
* OUTPUT
*   
* RETURNS
*   
* AUTHOR
*
*   POV-Ray Team
*   
* DESCRIPTION
*
*   -
*
* CHANGES
*
*   -
*
******************************************************************************/

static void Scale_Plane (Object, Vector, Trans)
OBJECT *Object;
VECTOR Vector;
TRANSFORM *Trans;
{
  DBL Length;
  PLANE *Plane = (PLANE  *) Object;

  if (Plane->Trans == NULL)
  {
    VDivEq(Plane->Normal_Vector, Vector);

    VLength(Length, ((PLANE *)Object)->Normal_Vector);

    VInverseScaleEq (((PLANE *)Object)->Normal_Vector, Length);

    ((PLANE *)Object)->Distance /= Length;

    Compute_Plane_BBox(Plane);
  }
  else
  {
    Transform_Plane (Object, Trans);
  }
}



/*****************************************************************************
*
* FUNCTION
*
*   Invert_Plane
*
* INPUT
*
* OUTPUT
*
* RETURNS
*
* AUTHOR
*
*   POV-Ray Team
*
* DESCRIPTION
*
*   -
*
* CHANGES
*
*   -
*
******************************************************************************/

static void Invert_Plane (Object)
OBJECT *Object;
{
  VScaleEq(((PLANE *)Object)->Normal_Vector, -1.0);

  ((PLANE *)Object)->Distance *= -1.0;
}



/*****************************************************************************
*
* FUNCTION
*
*   Transform_Plane
*
* INPUT
*
* OUTPUT
*
* RETURNS
*
* AUTHOR
*
*   POV-Ray Team
*
* DESCRIPTION
*
*   -
*
* CHANGES
*
*   -
*
******************************************************************************/

static void Transform_Plane(Object, Trans)
OBJECT *Object;
TRANSFORM *Trans;
{
  PLANE *Plane = (PLANE  *) Object;

  if (Plane->Trans == NULL)
  {
    Plane->Trans = Create_Transform();
  }

  Compose_Transforms(Plane->Trans, Trans);

  Compute_Plane_BBox(Plane);
}



/*****************************************************************************
*
* FUNCTION
*
*   Create_Plane
*
* INPUT
*
* OUTPUT
*
* RETURNS
*
* AUTHOR
*
*   POV-Ray Team
*   
* DESCRIPTION
*
*   -
*
* CHANGES
*
*   -
*
******************************************************************************/

PLANE *Create_Plane()
{
  PLANE *New;

  New = (PLANE *)POV_MALLOC(sizeof (PLANE), "plane");

  INIT_OBJECT_FIELDS(New,PLANE_OBJECT,&Plane_Methods)

  Make_Vector(New->Normal_Vector, 0.0, 1.0, 0.0);

  New ->Distance = 0.0;

  New->Trans = NULL;

  return(New);
}



/*****************************************************************************
*
* FUNCTION
*
*   Copy_Plane
*
* INPUT
*   
* OUTPUT
*   
* RETURNS
*   
* AUTHOR
*
*   POV-Ray Team
*   
* DESCRIPTION
*
*   -
*
* CHANGES
*
*   -
*
******************************************************************************/

static void *Copy_Plane (Object)
OBJECT *Object;
{
  PLANE *New;

  New = Create_Plane();

  Destroy_Transform(New->Trans);

  *New = *((PLANE *)Object);

  New->Trans = Copy_Transform(((PLANE *)Object)->Trans);

  return(New);
}



/*****************************************************************************
*
* FUNCTION
*
*   Destroy_Plane
*
* INPUT
*   
* OUTPUT
*   
* RETURNS
*   
* AUTHOR
*
*   POV-Ray Team
*   
* DESCRIPTION
*
*   -
*
* CHANGES
*
*   -
*
******************************************************************************/

static void Destroy_Plane(Object)
OBJECT *Object;
{
  Destroy_Transform(((PLANE *)Object)->Trans);

  POV_FREE(Object);
}



/*****************************************************************************
*
* FUNCTION
*
*   Compute_Plane_BBox
*
* INPUT
*
*   Plane - Plane
*   
* OUTPUT
*
*   Plane
*   
* RETURNS
*   
* AUTHOR
*
*   Dieter Bayer
*   
* DESCRIPTION
*
*   Calculate the bounding box of a plane (it's always infinite).
*
* CHANGES
*
*   Aug 1994 : Creation.
*
******************************************************************************/

void Compute_Plane_BBox(Plane)
PLANE *Plane;
{
  Make_BBox(Plane->BBox, -BOUND_HUGE/2, -BOUND_HUGE/2, -BOUND_HUGE/2,
    BOUND_HUGE, BOUND_HUGE, BOUND_HUGE);

  if (Plane->Clip != NULL)
  {
    Plane->BBox = Plane->Clip->BBox;
  }
}

