textureAttrib.cxx

// Filename: textureAttrib.cxx
// Created by:  drose (21Feb02)
//
////////////////////////////////////////////////////////////////////
//
// PANDA 3D SOFTWARE
// Copyright (c) Carnegie Mellon University.  All rights reserved.
//
// All use of this software is subject to the terms of the revised BSD
// license.  You should have received a copy of this license along
// with this source code in a file named "LICENSE."
//
////////////////////////////////////////////////////////////////////

#include "textureAttrib.h"
#include "graphicsStateGuardianBase.h"
#include "internalName.h"
#include "bamReader.h"
#include "bamWriter.h"
#include "datagram.h"
#include "datagramIterator.h"
#include "dcast.h"
#include "textureStagePool.h"

CPT(RenderAttrib) TextureAttrib::_empty_attrib;
CPT(RenderAttrib) TextureAttrib::_all_off_attrib;
TypeHandle TextureAttrib::_type_handle;
int TextureAttrib::_attrib_slot;


////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::make
//       Access: Published, Static
//  Description: Constructs a new TextureAttrib object suitable for
//               rendering the indicated texture onto geometry, using
//               the default TextureStage.
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) TextureAttrib::
make(Texture *texture) {
  return DCAST(TextureAttrib, make())->add_on_stage(TextureStage::get_default(), texture);
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::make_off
//       Access: Published, Static
//  Description: Constructs a new TextureAttrib object suitable for
//               rendering untextured geometry.
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) TextureAttrib::
make_off() {
  return make_all_off();
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::make
//       Access: Published, Static
//  Description: Constructs a new TextureAttrib object that does
//               nothing.
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) TextureAttrib::
make() {
  // We make it a special case and store a pointer to the empty attrib
  // forever once we find it the first time, as an optimization.
  if (_empty_attrib == (RenderAttrib *)NULL) {
    _empty_attrib = return_new(new TextureAttrib);
  }

  return _empty_attrib;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::make_all_off
//       Access: Published, Static
//  Description: Constructs a new TextureAttrib object that turns off
//               all stages (and hence disables texturing).
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) TextureAttrib::
make_all_off() {
  // We make it a special case and store a pointer to the off attrib
  // forever once we find it the first time, as an optimization.
  if (_all_off_attrib == (RenderAttrib *)NULL) {
    TextureAttrib *attrib = new TextureAttrib;
    attrib->_off_all_stages = true;
    _all_off_attrib = return_new(attrib);
  }

  return _all_off_attrib;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::make_default
//       Access: Published, Static
//  Description: Returns a RenderAttrib that corresponds to whatever
//               the standard default properties for render attributes
//               of this type ought to be.
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) TextureAttrib::
make_default() {
  return make();
}


////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::find_on_stage
//       Access: Published
//  Description: Returns the index number of the indicated
//               TextureStage within the list of on_stages, or -1 if
//               the indicated stage is not listed.
////////////////////////////////////////////////////////////////////
int TextureAttrib::
find_on_stage(const TextureStage *stage) const {
  Stages::const_iterator si = _on_stages.find(StageNode(stage));
  if (si != _on_stages.end()) {
    return (int)(si - _on_stages.begin());
  }

  return -1;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::add_on_stage
//       Access: Published
//  Description: Returns a new TextureAttrib, just like this one, but
//               with the indicated stage added to the list of stages
//               turned on by this attrib.
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) TextureAttrib::
add_on_stage(TextureStage *stage, Texture *tex, int override) const {
  TextureAttrib *attrib = new TextureAttrib(*this);
  Stages::iterator si = attrib->_on_stages.insert(StageNode(stage)).first;
  (*si)._override = override;
  (*si)._texture = tex;
  (*si)._implicit_sort = attrib->_next_implicit_sort;
  ++(attrib->_next_implicit_sort);

  // We now need to re-sort the attrib list.
  attrib->_sort_seq = UpdateSeq::old();
  attrib->_filtered_seq = UpdateSeq::old();

  return return_new(attrib);
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::remove_on_stage
//       Access: Published
//  Description: Returns a new TextureAttrib, just like this one, but
//               with the indicated stage removed from the list of
//               stages turned on by this attrib.
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) TextureAttrib::
remove_on_stage(TextureStage *stage) const {
  TextureAttrib *attrib = new TextureAttrib(*this);

  Stages::iterator si = attrib->_on_stages.find(StageNode(stage));
  if (si != attrib->_on_stages.end()) {
    attrib->_on_stages.erase(si);

    attrib->_sort_seq = UpdateSeq::old();
    attrib->_filtered_seq = UpdateSeq::old();
  }

  return return_new(attrib);
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::add_off_stage
//       Access: Published
//  Description: Returns a new TextureAttrib, just like this one, but
//               with the indicated stage added to the list of stages
//               turned off by this attrib.
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) TextureAttrib::
add_off_stage(TextureStage *stage, int override) const {
  TextureAttrib *attrib = new TextureAttrib(*this);
  if (!_off_all_stages) {
    StageNode sn(stage);
    Stages::iterator sfi = attrib->_off_stages.insert(sn).first;
    (*sfi)._override = override;

    // Also ensure it is removed from the on_stages list.
    Stages::iterator si = attrib->_on_stages.find(sn);
    if (si != attrib->_on_stages.end()) {
      attrib->_on_stages.erase(si);
      attrib->_sort_seq = UpdateSeq::old();
      attrib->_filtered_seq = UpdateSeq::old();
    }
  }
  return return_new(attrib);
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::remove_off_stage
//       Access: Published
//  Description: Returns a new TextureAttrib, just like this one, but
//               with the indicated stage removed from the list of
//               stages turned off by this attrib.
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) TextureAttrib::
remove_off_stage(TextureStage *stage) const {
  TextureAttrib *attrib = new TextureAttrib(*this);
  attrib->_off_stages.erase(StageNode(stage));
  return return_new(attrib);
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::unify_texture_stages
//       Access: Published
//  Description: Returns a new TextureAttrib, just like this one, but
//               with any included TextureAttribs that happen to have
//               the same name as the given object replaced with the
//               object.
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) TextureAttrib::
unify_texture_stages(TextureStage *stage) const {
  PT(TextureAttrib) attrib = new TextureAttrib;

  attrib->_off_all_stages = _off_all_stages;
  bool any_changed = false;

  Stages::const_iterator si;
  for (si = _on_stages.begin(); si != _on_stages.end(); ++si) {
    TextureStage *this_stage = (*si)._stage;

    if (this_stage->get_name() == stage->get_name()) {
      this_stage = stage;
      any_changed = true;
    }

    Stages::iterator osi = attrib->_on_stages.insert(StageNode(this_stage)).first;
    (*osi)._texture = (*si)._texture;
    (*osi)._ff_tc_index = (*si)._ff_tc_index;
    (*osi)._implicit_sort = (*si)._implicit_sort;
    (*osi)._override = (*si)._override;
  }

  attrib->_next_implicit_sort = _next_implicit_sort;

  Stages::const_iterator fsi;
  for (fsi = _off_stages.begin(); fsi != _off_stages.end(); ++fsi) {
    TextureStage *this_stage = (*fsi)._stage;

    if (this_stage != stage && 
        this_stage->get_name() == stage->get_name()) {
      this_stage = stage;
      any_changed = true;
    }

    attrib->_off_stages.insert(StageNode(this_stage));
  }

  if (!any_changed) {
    return this;
  }

  return return_new(attrib);
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::filter_to_max
//       Access: Public
//  Description: Returns a new TextureAttrib, very much like this one,
//               but with the number of on_stages reduced to be no
//               more than max_texture_stages.  The number of
//               off_stages in the new TextureAttrib is undefined.
////////////////////////////////////////////////////////////////////
CPT(TextureAttrib) TextureAttrib::
filter_to_max(int max_texture_stages) const {
  if ((int)_on_stages.size() <= max_texture_stages) {
    // Trivial case: this TextureAttrib qualifies.
    return this;
  }

  if (_filtered_seq != TextureStage::get_sort_seq()) {
    ((TextureAttrib *)this)->_filtered.clear();
    ((TextureAttrib *)this)->_filtered_seq = TextureStage::get_sort_seq();
  }

  Filtered::const_iterator fi;
  fi = _filtered.find(max_texture_stages);
  if (fi != _filtered.end()) {
    // Easy case: we have already computed this for this particular
    // TextureAttrib.
    return (*fi).second;
  }

  // Harder case: we have to compute it now.  We must choose the n
  // stages with the highest priority in our list of stages.  In the
  // case of equal priority, we prefer the stage with the lower sort.
  check_sorted();

  RenderStages priority_stages = _render_stages;

  // This sort function uses the STL function object defined above.
  sort(priority_stages.begin(), priority_stages.end(), 
       CompareTextureStagePriorities());

  // Now lop off all of the stages after the first max_texture_stages.
  priority_stages.erase(priority_stages.begin() + max_texture_stages,
                        priority_stages.end());

  // And create a new attrib reflecting these stages.
  PT(TextureAttrib) attrib = new TextureAttrib;

  RenderStages::const_iterator ri;
  for (ri = priority_stages.begin(); ri != priority_stages.end(); ++ri) {
    attrib->_on_stages.insert(*(*ri));
  }

  attrib->_next_implicit_sort = _next_implicit_sort;

  CPT(RenderAttrib) new_attrib = return_new(attrib);

  // Finally, record this newly-created attrib in the map for next
  // time.
  CPT(TextureAttrib) tex_attrib = (const TextureAttrib *)new_attrib.p();
  ((TextureAttrib *)this)->_filtered[max_texture_stages] = tex_attrib;
  return tex_attrib;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::lower_attrib_can_override
//       Access: Public, Virtual
//  Description: Intended to be overridden by derived RenderAttrib
//               types to specify how two consecutive RenderAttrib
//               objects of the same type interact.
//
//               This should return false if a RenderAttrib on a
//               higher node will compose into a RenderAttrib on a
//               lower node that has a higher override value, or false
//               if the lower RenderAttrib will completely replace the
//               state.
//
//               The default behavior is false: normally, a
//               RenderAttrib in the graph cannot completely override
//               a RenderAttrib above it, regardless of its override
//               value--instead, the two attribs are composed.  But
//               for some kinds of RenderAttribs, it is useful to
//               allow this kind of override.
//
//               This method only handles the one special case of a
//               lower RenderAttrib with a higher override value.  If
//               the higher RenderAttrib has a higher override value,
//               it always completely overrides.  And if both
//               RenderAttribs have the same override value, they are
//               always composed.
////////////////////////////////////////////////////////////////////
bool TextureAttrib::
lower_attrib_can_override() const {
  // A TextureAttrib doesn't compose through an override.  Normally,
  // there won't be a scene-graph override on a TextureAttrib anyway,
  // since the NodePath::set_texture() override is applied to the
  // per-TextureStage override value.  But there might be a
  // scene-graph override if NodePath::adjust_all_priorities() is
  // used, and in this case, we'd like for it to stick.
  return true;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::output
//       Access: Public, Virtual
//  Description: 
////////////////////////////////////////////////////////////////////
void TextureAttrib::
output(ostream &out) const {
  check_sorted();

  out << get_type() << ":";
  if (_off_stages.empty()) {
    if (_on_stages.empty()) {
      if (_off_all_stages) {
        out << "all off";
      } else {
        out << "identity";
      }
    } else {
      if (_off_all_stages) {
        out << "set";
      } else {
        out << "on";
      }
    }

  } else {
    out << "off";
    Stages::const_iterator fi;
    for (fi = _off_stages.begin(); fi != _off_stages.end(); ++fi) {
      TextureStage *stage = (*fi)._stage;
      out << " " << stage->get_name();
      if ((*fi)._override != 0) {
        out << "^" << (*fi)._override;
      }
    }

    if (!_on_stages.empty()) {
      out << " on";
    }
  }
    
  RenderStages::const_iterator ri;
  for (ri = _render_stages.begin(); ri != _render_stages.end(); ++ri) {
    const StageNode &sn = *(*ri);
    TextureStage *stage = sn._stage;
    Texture *tex = sn._texture;
    if (tex != NULL) {
      out << " " << stage->get_name() << ":" << tex->get_name();
    } else {
      out << " " << stage->get_name();
    }
    if (sn._override != 0) {
      out << "^" << sn._override;
    }
  }
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::has_cull_callback
//       Access: Public, Virtual
//  Description: Should be overridden by derived classes to return
//               true if cull_callback() has been defined.  Otherwise,
//               returns false to indicate cull_callback() does not
//               need to be called for this node during the cull
//               traversal.
////////////////////////////////////////////////////////////////////
bool TextureAttrib::
has_cull_callback() const {
  Stages::const_iterator si;
  for (si = _on_stages.begin(); si != _on_stages.end(); ++si) {
    Texture *texture = (*si)._texture;
    if (texture->has_cull_callback()) {
      return true;
    }
  }

  return false;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::cull_callback
//       Access: Public, Virtual
//  Description: If has_cull_callback() returns true, this function
//               will be called during the cull traversal to perform
//               any additional operations that should be performed at
//               cull time.
//
//               This is called each time the RenderAttrib is
//               discovered applied to a Geom in the traversal.  It
//               should return true if the Geom is visible, false if
//               it should be omitted.
////////////////////////////////////////////////////////////////////
bool TextureAttrib::
cull_callback(CullTraverser *trav, const CullTraverserData &data) const {
  Stages::const_iterator si;
  for (si = _on_stages.begin(); si != _on_stages.end(); ++si) {
    Texture *texture = (*si)._texture;
    if (!texture->cull_callback(trav, data)) {
      return false;
    }
  }

  return true;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::compare_to_impl
//       Access: Protected, Virtual
//  Description: Intended to be overridden by derived TextureAttrib
//               types to return a unique number indicating whether
//               this TextureAttrib is equivalent to the other one.
//
//               This should return 0 if the two TextureAttrib objects
//               are equivalent, a number less than zero if this one
//               should be sorted before the other one, and a number
//               greater than zero otherwise.
//
//               This will only be called with two TextureAttrib
//               objects whose get_type() functions return the same.
////////////////////////////////////////////////////////////////////
int TextureAttrib::
compare_to_impl(const RenderAttrib *other) const {
  const TextureAttrib *ta;
  DCAST_INTO_R(ta, other, 0);

  if (_off_all_stages != ta->_off_all_stages) {
    return (int)_off_all_stages - (int)ta->_off_all_stages;
  }

  Stages::const_iterator si = _on_stages.begin();
  Stages::const_iterator osi = ta->_on_stages.begin();

  while (si != _on_stages.end() && osi != ta->_on_stages.end()) {
    TextureStage *stage = (*si)._stage;
    TextureStage *other_stage = (*osi)._stage;

    if (stage != other_stage) {
      return stage < other_stage ? -1 : 1;
    }

    Texture *texture = (*si)._texture;
    Texture *other_texture = (*osi)._texture;

    if (texture != other_texture) {
      return texture < other_texture ? -1 : 1;
    }

    int implicit_sort = (*si)._implicit_sort;
    int other_implicit_sort = (*osi)._implicit_sort;

    if (implicit_sort != other_implicit_sort) {
      return implicit_sort < other_implicit_sort ? -1 : 1;
    }

    int override = (*si)._override;
    int other_override = (*osi)._override;

    if (override != other_override) {
      return override < other_override ? -1 : 1;
    }

    ++si;
    ++osi;
  }

  if (si != _on_stages.end()) {
    return 1;
  }
  if (osi != ta->_on_stages.end()) {
    return -1;
  }

  // Finally, ensure that the set of off stages is the same.
  Stages::const_iterator fi = _off_stages.begin();
  Stages::const_iterator ofi = ta->_off_stages.begin();

  while (fi != _off_stages.end() && ofi != ta->_off_stages.end()) {
    TextureStage *stage = (*fi)._stage;
    TextureStage *other_stage = (*ofi)._stage;

    if (stage != other_stage) {
      return stage < other_stage ? -1 : 1;
    }

    int override = (*fi)._override;
    int other_override = (*ofi)._override;

    if (override != other_override) {
      return override < other_override ? -1 : 1;
    }

    ++fi;
    ++ofi;
  }

  if (fi != _off_stages.end()) {
    return 1;
  }
  if (ofi != ta->_off_stages.end()) {
    return -1;
  }
  
  return 0;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::compose_impl
//       Access: Protected, Virtual
//  Description: Intended to be overridden by derived RenderAttrib
//               types to specify how two consecutive RenderAttrib
//               objects of the same type interact.
//
//               This should return the result of applying the other
//               RenderAttrib to a node in the scene graph below this
//               RenderAttrib, which was already applied.  In most
//               cases, the result is the same as the other
//               RenderAttrib (that is, a subsequent RenderAttrib
//               completely replaces the preceding one).  On the other
//               hand, some kinds of RenderAttrib (for instance,
//               ColorTransformAttrib) might combine in meaningful
//               ways.
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) TextureAttrib::
compose_impl(const RenderAttrib *other) const {
  const TextureAttrib *ta;
  DCAST_INTO_R(ta, other, 0);

  if (ta->_off_all_stages) {
    // If the other type turns off all stages, it doesn't matter what
    // we are.
    return ta;
  }

  // This is a three-way merge between ai, bi, and ci, except that bi
  // and ci should have no intersection and therefore needn't be
  // compared to each other.
  Stages::const_iterator ai = _on_stages.begin();
  Stages::const_iterator bi = ta->_on_stages.begin();
  Stages::const_iterator ci = ta->_off_stages.begin();

  // Create a new TextureAttrib that will hold the result.
  TextureAttrib *attrib = new TextureAttrib;

  while (ai != _on_stages.end() && 
         bi != ta->_on_stages.end() && 
         ci != ta->_off_stages.end()) {
    if ((*ai)._stage < (*bi)._stage) {
      if ((*ai)._stage < (*ci)._stage) {
        // Here is a stage that we have in the original, which is not
        // present in the secondary.
        attrib->_on_stages.insert(attrib->_on_stages.end(), *ai);
        ++ai;

      } else if ((*ci)._stage < (*ai)._stage) {
        // Here is a stage that is turned off in the secondary, but
        // was not present in the original.
        ++ci;

      } else { // (*ci)._stage == (*ai)._stage
        // Here is a stage that is turned off in the secondary, and
        // was present in the original.
        if ((*ai)._override > (*ci)._override) {
          // But never mind, keep it anyway.
          attrib->_on_stages.insert(attrib->_on_stages.end(), *ai);
        }

        ++ai;
        ++ci;
      }

    } else if ((*bi)._stage < (*ai)._stage) {
      // Here is a new stage we have in the secondary, that was not
      // present in the original.
      attrib->_on_stages.insert(attrib->_on_stages.end(), *bi);
      ++bi;

    } else {  // (*bi)._stage == (*ai)._stage
      // Here is a stage we have in both.
      if ((*ai)._override > (*bi)._override) {
        attrib->_on_stages.insert(attrib->_on_stages.end(), *ai);
      } else {
        attrib->_on_stages.insert(attrib->_on_stages.end(), *bi);
      }
      ++ai;
      ++bi;
    }
  }

  while (ai != _on_stages.end() && bi != ta->_on_stages.end()) {
    if ((*ai)._stage < (*bi)._stage) {
      // Here is a stage that we have in the original, which is not
      // present in the secondary.
      attrib->_on_stages.insert(attrib->_on_stages.end(), *ai);
      ++ai;

    } else if ((*bi)._stage < (*ai)._stage) {
      // Here is a new stage we have in the secondary, that was not
      // present in the original.
      attrib->_on_stages.insert(attrib->_on_stages.end(), *bi);
      ++bi;

    } else {
      // Here is a stage we have in both.
      if ((*ai)._override > (*bi)._override) {
        attrib->_on_stages.insert(attrib->_on_stages.end(), *ai);
      } else {
        attrib->_on_stages.insert(attrib->_on_stages.end(), *bi);
      }
      ++ai;
      ++bi;
    }
  }

  while (ai != _on_stages.end() && ci != ta->_off_stages.end()) {
    if ((*ai)._stage < (*ci)._stage) {
      // Here is a stage that we have in the original, which is not
      // present in the secondary.
      attrib->_on_stages.insert(attrib->_on_stages.end(), *ai);
      ++ai;
      
    } else if ((*ci)._stage < (*ai)._stage) {
      // Here is a stage that is turned off in the secondary, but
      // was not present in the original.
      ++ci;
      
    } else { // (*ci)._stage == (*ai)._stage
      // Here is a stage that is turned off in the secondary, and
      // was present in the original.
      if ((*ai)._override > (*ci)._override) {
        // But never mind, keep it anyway.
        attrib->_on_stages.insert(attrib->_on_stages.end(), *ai);
      }
      ++ai;
      ++ci;
    }
  }

  while (ai != _on_stages.end()) {
    attrib->_on_stages.insert(attrib->_on_stages.end(), *ai);
    ++ai;
  }

  while (bi != ta->_on_stages.end()) {
    attrib->_on_stages.insert(attrib->_on_stages.end(), *bi);
    ++bi;
  }

  attrib->_next_implicit_sort = _next_implicit_sort + ta->_next_implicit_sort;
  attrib->_sort_seq = UpdateSeq::old();
  attrib->_filtered_seq = UpdateSeq::old();

  return return_new(attrib);
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::invert_compose_impl
//       Access: Protected, Virtual
//  Description: Intended to be overridden by derived RenderAttrib
//               types to specify how two consecutive RenderAttrib
//               objects of the same type interact.
//
//               See invert_compose() and compose_impl().
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) TextureAttrib::
invert_compose_impl(const RenderAttrib *other) const {
  // I think in this case the other attrib always wins.  Maybe this
  // needs a bit more thought.  It's hard to imagine that it's even
  // important to compute this properly.
  return other;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::register_with_read_factory
//       Access: Public, Static
//  Description: Tells the BamReader how to create objects of type
//               TextureAttrib.
////////////////////////////////////////////////////////////////////
void TextureAttrib::
register_with_read_factory() {
  BamReader::get_factory()->register_factory(get_class_type(), make_from_bam);
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::write_datagram
//       Access: Public, Virtual
//  Description: Writes the contents of this object to the datagram
//               for shipping out to a Bam file.
////////////////////////////////////////////////////////////////////
void TextureAttrib::
write_datagram(BamWriter *manager, Datagram &dg) {
  RenderAttrib::write_datagram(manager, dg);

  // Write the off_stages information
  dg.add_bool(_off_all_stages);
  dg.add_uint16(get_num_off_stages());
  Stages::const_iterator fi;
  for (fi = _off_stages.begin(); fi != _off_stages.end(); ++fi) {
    TextureStage *stage = (*fi)._stage;
    manager->write_pointer(dg, stage);
  }

  // Write the on_stages information
  dg.add_uint16(get_num_on_stages());
  Stages::const_iterator si;
  for (si = _on_stages.begin(); si != _on_stages.end(); ++si) {
    TextureStage *stage = (*si)._stage;
    Texture *tex = (*si)._texture;
    nassertv(tex != (Texture *)NULL);

    manager->write_pointer(dg, stage);
    manager->write_pointer(dg, tex);
    dg.add_uint16((*si)._implicit_sort);
    dg.add_int32((*si)._override);
  }
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::complete_pointers
//       Access: Public, Virtual
//  Description: Receives an array of pointers, one for each time
//               manager->read_pointer() was called in fillin().
//               Returns the number of pointers processed.
////////////////////////////////////////////////////////////////////
int TextureAttrib::
complete_pointers(TypedWritable **p_list, BamReader *manager) {
  int pi = RenderAttrib::complete_pointers(p_list, manager);

  Stages::iterator ci;
  for (ci = _off_stages.begin(); ci != _off_stages.end(); ++ci) {
    TextureStage *ts = DCAST(TextureStage, p_list[pi++]);
    *ci = StageNode(ts);
  }

  size_t sni = 0;
  while (sni < _on_stages.size()) {
    // Filter the TextureStage through the TextureStagePool.
    PT(TextureStage) ts = DCAST(TextureStage, p_list[pi++]);
    ts = TextureStagePool::get_stage(ts);

    // The Texture pointer filters itself through the TexturePool, so
    // we don't have to do anything special here.
    Texture *tex = DCAST(Texture, p_list[pi++]);
    
    if (tex != (Texture *)NULL) {
      StageNode &sn = _on_stages[sni];
      sn._stage = ts;
      sn._texture = tex;
      ++sni;
      
    } else {
      // If we couldn't load a texture pointer, turn off that
      // particular texture stage.
      _off_stages.push_back(StageNode(ts));
      _on_stages.erase(_on_stages.begin() + sni);
    }
  }
  _on_stages.sort();
  _sort_seq = UpdateSeq::old();
  _filtered_seq = UpdateSeq::old();

  return pi;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::make_from_bam
//       Access: Protected, Static
//  Description: This function is called by the BamReader's factory
//               when a new object of type TextureAttrib is encountered
//               in the Bam file.  It should create the TextureAttrib
//               and extract its information from the file.
////////////////////////////////////////////////////////////////////
TypedWritable *TextureAttrib::
make_from_bam(const FactoryParams &params) {
  TextureAttrib *attrib = new TextureAttrib;
  DatagramIterator scan;
  BamReader *manager;

  parse_params(params, scan, manager);
  attrib->fillin(scan, manager);

  return attrib;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::fillin
//       Access: Protected
//  Description: This internal function is called by make_from_bam to
//               read in all of the relevant data from the BamFile for
//               the new TextureAttrib.
////////////////////////////////////////////////////////////////////
void TextureAttrib::
fillin(DatagramIterator &scan, BamReader *manager) {
  RenderAttrib::fillin(scan, manager);

  // read the _off_stages data.
  _off_all_stages = scan.get_bool();
  int num_off_stages = scan.get_uint16();
  
  // Push back a NULL pointer for each off TextureStage for now, until
  // we get the actual list of pointers later in complete_pointers().
  int i;
  _off_stages.reserve(num_off_stages);
  for (i = 0; i < num_off_stages; i++) {
    manager->read_pointer(scan);
    _off_stages.push_back(StageNode(NULL));
  }

  // Read the _on_stages data.
  int num_on_stages = scan.get_uint16();

  // Push back a NULL pointer for each off TextureStage and Texture
  // for now, until we get the actual list of pointers later in
  // complete_pointers().
  _on_stages.reserve(num_on_stages);
  _next_implicit_sort = 0;
  for (i = 0; i < num_on_stages; i++) {
    manager->read_pointer(scan);
    manager->read_pointer(scan);
    unsigned int implicit_sort;
    if (manager->get_file_minor_ver() >= 15) {
      implicit_sort = scan.get_uint16();
    } else {
      implicit_sort = (unsigned int)i;
    }
    int override = 0;
    if (manager->get_file_minor_ver() >= 23) {
      override = scan.get_int32();
    }

    _next_implicit_sort = max(_next_implicit_sort, implicit_sort + 1);
    _on_stages.push_back(StageNode(NULL, _next_implicit_sort, override));
    ++_next_implicit_sort;
  }
}

////////////////////////////////////////////////////////////////////
//     Function: TextureAttrib::sort_on_stages
//       Access: Private
//  Description: Sorts the list of stages so that they are listed in
//               render order.  Also clears the _filtered map and
//               recalculates the list of fixed-function stages.
////////////////////////////////////////////////////////////////////
void TextureAttrib::
sort_on_stages() {
  typedef pmap<const InternalName *, int> UsedTexcoordIndex;
  UsedTexcoordIndex used_texcoord_index;

  _render_stages.clear();
  _render_ff_stages.clear();

  Stages::iterator si;
  for (si = _on_stages.begin(); si != _on_stages.end(); ++si) {
    StageNode &sn = (*si);
    TextureStage *stage = sn._stage;
    nassertv(stage != NULL);
    if (stage->is_fixed_function()) {
      const InternalName *name = stage->get_texcoord_name();

      // This pair of lines will get the next consecutive texcoord index
      // number if this is the first time we have referenced this
      // particular texcoord name; otherwise, it will return the same
      // index number it returned before.
      UsedTexcoordIndex::iterator ti = used_texcoord_index.insert(UsedTexcoordIndex::value_type(name, (int)used_texcoord_index.size())).first;
      (*si)._ff_tc_index = (*ti).second;

      _render_ff_stages.push_back(&sn);
    } else {
      (*si)._ff_tc_index = -1;
    }

    _render_stages.push_back(&sn);
  }

  sort(_render_stages.begin(), _render_stages.end(), CompareTextureStageSort());
  sort(_render_ff_stages.begin(), _render_ff_stages.end(), CompareTextureStageSort());

  // We'd like to clear the _filtered map, in case the TextureStage
  // priority values have changed as well, but we can't do that here:
  // it's too dangerous.  Clearing _filtered might cause
  // TextureAttribs to be deleted, and hence removed from the map that
  // we might be in the middle of traversing!

  _sort_seq = TextureStage::get_sort_seq();
}