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panda/src/mathutil/boundingVolume.I

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// Filename: boundingVolume.I
// Created by:  drose (01Oct99)
//
////////////////////////////////////////////////////////////////////
//
// PANDA 3D SOFTWARE
// Copyright (c) 2001, Disney Enterprises, Inc.  All rights reserved
//
// All use of this software is subject to the terms of the Panda 3d
// Software license.  You should have received a copy of this license
// along with this source code; you will also find a current copy of
// the license at http://www.panda3d.org/license.txt .
//
// To contact the maintainers of this program write to
// panda3d@yahoogroups.com .
//
////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////
//     Function: BoundingVolume::Constructor
//       Access: Public
//  Description:
////////////////////////////////////////////////////////////////////
INLINE_MATHUTIL BoundingVolume::
BoundingVolume() {
  _flags = F_empty;
}

////////////////////////////////////////////////////////////////////
//     Function: BoundingVolume::is_empty
//       Access: Public
//  Description: Any kind of volume might be empty.  This is a
//               degenerate volume that contains no points; it's not
//               the same as, for instance, a sphere with radius zero,
//               since that contains one point (the center).  It
//               intersects with no other volumes.
////////////////////////////////////////////////////////////////////
INLINE_MATHUTIL bool BoundingVolume::
is_empty() const {
  return (_flags & F_empty) != 0;
}

////////////////////////////////////////////////////////////////////
//     Function: BoundingVolume::is_infinite
//       Access: Public
//  Description: The other side of the empty coin is an infinite
//               volume.  This is a degenerate state of a normally
//               finite volume that contains all points.  (Note that
//               some kinds of infinite bounding volumes, like binary
//               separating planes, do not contain all points and thus
//               correctly return is_infinite() == false, even though
//               they are technically infinite.  This is a special
//               case of the word 'infinite' meaning the volume covers
//               all points in space.)
//
//               It completely intersects with all other volumes
//               except empty volumes.
////////////////////////////////////////////////////////////////////
INLINE_MATHUTIL bool BoundingVolume::
is_infinite() const {
  return (_flags & F_infinite) != 0;
}

////////////////////////////////////////////////////////////////////
//     Function: BoundingVolume::set_infinite
//       Access: Public
//  Description: Marks the volume as infinite, even if it is normally
//               finite.  You can think of this as an infinite
//               extend_by() operation.
////////////////////////////////////////////////////////////////////
INLINE_MATHUTIL void BoundingVolume::
set_infinite() {
  _flags = F_infinite;
}

////////////////////////////////////////////////////////////////////
//     Function: BoundingVolume::extend_by
//       Access: Public
//  Description: Increases the size of the volume to include the given
//               volume.
////////////////////////////////////////////////////////////////////
INLINE_MATHUTIL bool BoundingVolume::
extend_by(const BoundingVolume *vol) {
  if (vol->is_infinite()) {
    set_infinite();

  } else if (!vol->is_empty()) {
    // This is a double-dispatch.  We call this virtual function on the
    // volume we were given, which will in turn call the appropriate
    // virtual function in our own class to perform the operation.
    return vol->extend_other(this);
  }
  return true;
}


////////////////////////////////////////////////////////////////////
//     Function: BoundingVolume::contains
//       Access: Public
//  Description: Returns the appropriate set of IntersectionFlags to
//               indicate the amount of intersection with the
//               indicated volume.
////////////////////////////////////////////////////////////////////
INLINE_MATHUTIL int BoundingVolume::
contains(const BoundingVolume *vol) const {
  if (is_empty() || vol->is_empty()) {
    return IF_no_intersection;

  } else if (is_infinite()) {
    return IF_possible | IF_some | IF_all;

  } else if (vol->is_infinite()) {
    return IF_possible | IF_some;
  }

  // This is a double-dispatch.  We call this virtual function on the
  // volume we were given, which will in turn call the appropriate
  // virtual function in our own class to perform the operation.
  return vol->contains_other(this);
}

INLINE_MATHUTIL ostream &operator << (ostream &out, const BoundingVolume &bound) {
  bound.output(out);
  return out;
}

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