// Filename: textureReference.cxx
// Created by:  drose (29Nov00)
//
////////////////////////////////////////////////////////////////////
//
// 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 .
//
////////////////////////////////////////////////////////////////////

#include "textureReference.h"
#include "textureImage.h"
#include "paletteImage.h"
#include "sourceTextureImage.h"
#include "destTextureImage.h"
#include "texturePlacement.h"
#include "palettizer.h"
#include "eggFile.h"

#include "indent.h"
#include "eggTexture.h"
#include "eggData.h"
#include "eggGroupNode.h"
#include "eggGroup.h"
#include "eggNurbsSurface.h"
#include "eggVertexPool.h"
#include "datagram.h"
#include "datagramIterator.h"
#include "bamReader.h"
#include "bamWriter.h"
#include "string_utils.h"

#include <math.h>

TypeHandle TextureReference::_type_handle;

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::Constructor
//       Access: Public
//  Description:
////////////////////////////////////////////////////////////////////
TextureReference::
TextureReference() {
  _egg_file = (EggFile *)NULL;
  _egg_tex = (EggTexture *)NULL;
  _tex_mat = LMatrix3d::ident_mat();
  _inv_tex_mat = LMatrix3d::ident_mat();
  _source_texture = (SourceTextureImage *)NULL;
  _placement = (TexturePlacement *)NULL;
  _uses_alpha = false;
  _any_uvs = false;
  _min_uv.set(0.0, 0.0);
  _max_uv.set(0.0, 0.0);
  _wrap_u = EggTexture::WM_unspecified;
  _wrap_v = EggTexture::WM_unspecified;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::Destructor
//       Access: Public
//  Description:
////////////////////////////////////////////////////////////////////
TextureReference::
~TextureReference() {
  clear_placement();
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::from_egg
//       Access: Public
//  Description: Sets up the TextureReference using information
//               extracted from an egg file.
////////////////////////////////////////////////////////////////////
void TextureReference::
from_egg(EggFile *egg_file, EggData *data, EggTexture *egg_tex) {
  _egg_file = egg_file;
  _egg_tex = egg_tex;
  _egg_data = data;
  _tref_name = egg_tex->get_name();

  if (_egg_tex->has_transform()) {
    _tex_mat = _egg_tex->get_transform();
    if (!_inv_tex_mat.invert_from(_tex_mat)) {
      _inv_tex_mat = LMatrix3d::ident_mat();
    }
  } else {
    _tex_mat = LMatrix3d::ident_mat();
    _inv_tex_mat = LMatrix3d::ident_mat();
  }

  Filename filename = _egg_tex->get_filename();
  Filename alpha_filename;
  if (_egg_tex->has_alpha_filename()) {
    alpha_filename = _egg_tex->get_alpha_filename();
  }
  int alpha_file_channel = _egg_tex->get_alpha_file_channel();

  _properties._format = _egg_tex->get_format();
  _properties._minfilter = _egg_tex->get_minfilter();
  _properties._magfilter = _egg_tex->get_magfilter();
  _properties._anisotropic_degree = _egg_tex->get_anisotropic_degree();

  string name = filename.get_basename_wo_extension();
  TextureImage *texture = pal->get_texture(name);
  _source_texture = texture->get_source(filename, alpha_filename, 
                                        alpha_file_channel);
  _source_texture->update_properties(_properties);

  _uses_alpha = false;
  EggRenderMode::AlphaMode alpha_mode = _egg_tex->get_alpha_mode();
  if (alpha_mode == EggRenderMode::AM_unspecified) {
    if (_source_texture->get_size()) {
      _uses_alpha =
        _egg_tex->has_alpha_channel(_source_texture->get_num_channels());
    }

  } else if (alpha_mode == EggRenderMode::AM_off) {
    _uses_alpha = false;

  } else {
    _uses_alpha = true;
  }

  get_uv_range(_egg_data, pal->_remap_uv);

  _wrap_u = egg_tex->determine_wrap_u();
  _wrap_v = egg_tex->determine_wrap_v();
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::get_egg_file
//       Access: Public
//  Description: Returns the EggFile that references this texture.
////////////////////////////////////////////////////////////////////
EggFile *TextureReference::
get_egg_file() const {
  return _egg_file;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::get_source
//       Access: Public
//  Description: Returns the SourceTextureImage that this object
//               refers to.
////////////////////////////////////////////////////////////////////
SourceTextureImage *TextureReference::
get_source() const {
  return _source_texture;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::get_texture
//       Access: Public
//  Description: Returns the TextureImage that this object refers to.
////////////////////////////////////////////////////////////////////
TextureImage *TextureReference::
get_texture() const {
  nassertr(_source_texture != (SourceTextureImage *)NULL, (TextureImage *)NULL);
  return _source_texture->get_texture();
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::get_tref_name
//       Access: Public
//  Description: Returns the name of the EggTexture entry that
//               references this texture.
////////////////////////////////////////////////////////////////////
const string &TextureReference::
get_tref_name() const {
  return _tref_name;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::operator <
//       Access: Public
//  Description: Defines an ordering of TextureReference pointers in
//               alphabetical order by their tref name.
////////////////////////////////////////////////////////////////////
bool TextureReference::
operator < (const TextureReference &other) const {
  return _tref_name < other._tref_name;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::has_uvs
//       Access: Public
//  Description: Returns true if this TextureReference actually uses
//               the texture on geometry, with UV's and everything, or
//               false otherwise.  Strictly speaking, this should
//               always return true.
////////////////////////////////////////////////////////////////////
bool TextureReference::
has_uvs() const {
  return _any_uvs;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::get_min_uv
//       Access: Public
//  Description: Returns the minimum UV coordinate in use for the
//               texture by this reference.
////////////////////////////////////////////////////////////////////
const TexCoordd &TextureReference::
get_min_uv() const {
  nassertr(_any_uvs, _min_uv);
  return _min_uv;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::get_max_uv
//       Access: Public
//  Description: Returns the maximum UV coordinate in use for the
//               texture by this reference.
////////////////////////////////////////////////////////////////////
const TexCoordd &TextureReference::
get_max_uv() const {
  nassertr(_any_uvs, _max_uv);
  return _max_uv;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::get_wrap_u
//       Access: Public
//  Description: Returns the specification for the wrapping in the U
//               direction.
////////////////////////////////////////////////////////////////////
EggTexture::WrapMode TextureReference::
get_wrap_u() const {
  return _wrap_u;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::get_wrap_v
//       Access: Public
//  Description: Returns the specification for the wrapping in the V
//               direction.
////////////////////////////////////////////////////////////////////
EggTexture::WrapMode TextureReference::
get_wrap_v() const {
  return _wrap_v;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::is_equivalent
//       Access: Public
//  Description: Returns true if all essential properties of this
//               TextureReference are the same as that of the other,
//               or false if any of them differ.  This is useful when
//               reading a new egg file and comparing its references
//               to its previously-defined references.
////////////////////////////////////////////////////////////////////
bool TextureReference::
is_equivalent(const TextureReference &other) const {
  if (_source_texture != other._source_texture) {
    return false;
  }
  if (!_properties.egg_properties_match(other._properties)) {
    return false;
  }
  if (_uses_alpha != other._uses_alpha) {
    return false;
  }
  if (_any_uvs != other._any_uvs) {
    return false;
  }
  if (_wrap_u != other._wrap_u ||
      _wrap_v != other._wrap_v) {
    return false;
  }
  if (_any_uvs) {
    if (!_min_uv.almost_equal(other._min_uv, 0.00001)) {
      return false;
    }
    if (!_max_uv.almost_equal(other._max_uv, 0.00001)) {
      return false;
    }
  }
  if (!_tex_mat.almost_equal(other._tex_mat, 0.00001)) {
    return false;
  }

  return true;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::set_placement
//       Access: Public
//  Description: Sets the particular TexturePlacement that is
//               appropriate for this egg file.  This is called by
//               EggFile::choose_placements().
////////////////////////////////////////////////////////////////////
void TextureReference::
set_placement(TexturePlacement *placement) {
  if (_placement != placement) {
    if (_placement != (TexturePlacement *)NULL) {
      // Remove our reference from the old placement object.
      _placement->remove_egg(this);
    }
    _placement = placement;
    if (_placement != (TexturePlacement *)NULL) {
      // Add our reference to the new placement object.
      _placement->add_egg(this);
    }
  }
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::clear_placement
//       Access: Public
//  Description: Removes any reference to a TexturePlacement.
////////////////////////////////////////////////////////////////////
void TextureReference::
clear_placement() {
  set_placement((TexturePlacement *)NULL);
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::get_placement
//       Access: Public
//  Description: Returns the particular TexturePlacement that is
//               appropriate for this egg file.  This will not be
//               filled in until EggFile::choose_placements() has been
//               called.
////////////////////////////////////////////////////////////////////
TexturePlacement *TextureReference::
get_placement() const {
  return _placement;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::mark_egg_stale
//       Access: Public
//  Description: Marks the egg file that shares this reference as
//               stale.
////////////////////////////////////////////////////////////////////
void TextureReference::
mark_egg_stale() {
  if (_egg_file != (EggFile *)NULL) {
    _egg_file->mark_stale();
  }
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::update_egg
//       Access: Public
//  Description: Updates the egg file with all the relevant
//               information to reference the texture in its new home,
//               wherever that might be.
////////////////////////////////////////////////////////////////////
void TextureReference::
update_egg() {
  if (_egg_tex == (EggTexture *)NULL) {
    // Not much we can do if we don't have an actual egg file to
    // reference.
    return;
  }

  nassertv(_placement != (TexturePlacement *)NULL);

  // Make sure the alpha mode is set according to what the texture
  // image wants.
  TextureImage *texture = get_texture();
  if (texture != (TextureImage *)NULL) {
    if (texture->has_num_channels() && 
        !_egg_tex->has_alpha_channel(texture->get_num_channels())) {
      // The egg file doesn't want to use the alpha on the texture;
      // leave it unspecified so the egg loader can figure out whether
      // to enable alpha or not based on the object color.
      _egg_tex->set_alpha_mode(EggRenderMode::AM_unspecified);

    } else {
      // The egg file does want alpha, so get the alpha mode from the
      // texture.
      EggRenderMode::AlphaMode am = texture->get_alpha_mode();
      if (am != EggRenderMode::AM_unspecified) {
        _egg_tex->set_alpha_mode(am);
      }
    }
  }

  // We check for an OmitReason of OR_none, rather than asking
  // is_placed(), because in this case we don't want to consider an
  // OR_solitary texture as having been placed.
  if (_placement->get_omit_reason() == OR_unknown) {
    // The texture doesn't even exist.  We can't update the egg to
    // point to any meaningful path; just leave it pointing to the
    // source texture's basename.  Maybe it will be found along the
    // texture path later.
    Filename orig_filename = _egg_tex->get_filename();
    texture->update_egg_tex(_egg_tex);
    _egg_tex->set_filename(orig_filename.get_basename());
    return;
  }
  if (_placement->get_omit_reason() != OR_none) {
    // The texture exists but is not on a palette.  This is the easy
    // case; we simply have to update the texture reference to the new
    // texture location.
    DestTextureImage *dest = _placement->get_dest();
    nassertv(dest != (DestTextureImage *)NULL);
    dest->update_egg_tex(_egg_tex);
    return;
  }

  // The texture *does* appear on a palette.  This means we need to
  // not only update the texture reference, but also adjust the UV's.
  // In most cases, we can do this by simply applying a texture matrix
  // to the reference.
  PaletteImage *image = _placement->get_image();
  nassertv(image != (PaletteImage *)NULL);

  image->update_egg_tex(_egg_tex);
  // Palette images never wrap.
  _egg_tex->set_wrap_mode(EggTexture::WM_clamp);
  _egg_tex->set_wrap_u(EggTexture::WM_unspecified);
  _egg_tex->set_wrap_v(EggTexture::WM_unspecified);

  LMatrix3d new_tex_mat;
  _placement->compute_tex_matrix(new_tex_mat);

  // Compose the new texture matrix with whatever matrix was already
  // there, if any.
  _egg_tex->set_transform(_tex_mat * new_tex_mat);

  // Finally, go back and actually adjust the UV's to match what we
  // claimed they could be.
  update_uv_range(_egg_data, pal->_remap_uv);
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::apply_properties_to_source
//       Access: Public
//  Description: Applies the texture properties as read from the egg
//               file to the source image's properties.  This updates
//               the source image with the now-known properties
//               indicated with in the tref block of the egg file.
////////////////////////////////////////////////////////////////////
void TextureReference::
apply_properties_to_source() {
  nassertv(_source_texture != (SourceTextureImage *)NULL);
  _source_texture->update_properties(_properties);
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::output
//       Access: Public
//  Description:
////////////////////////////////////////////////////////////////////
void TextureReference::
output(ostream &out) const {
  out << *_source_texture;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::write
//       Access: Public
//  Description:
////////////////////////////////////////////////////////////////////
void TextureReference::
write(ostream &out, int indent_level) const {
  indent(out, indent_level)
    << get_texture()->get_name();

  if (_uses_alpha) {
    out << " (uses alpha)";
  }

  if (_any_uvs) {
    // Compute the fraction of the image that is covered by the UV's
    // minmax rectangle.
    TexCoordd box = _max_uv - _min_uv;
    double area = box[0] * box[1];

    out << " coverage " << area;
  }

  if (_wrap_u != EggTexture::WM_unspecified ||
      _wrap_v != EggTexture::WM_unspecified) {
    if (_wrap_u != _wrap_v) {
      out << " (" << _wrap_u << ", " << _wrap_v << ")";
    } else {
      out << " " << _wrap_u;
    }
  }

  if (_properties._format != EggTexture::F_unspecified) {
    out << " " << _properties._format;
  }

  switch (_properties._minfilter) {
      case EggTexture::FT_nearest_mipmap_nearest:
      case EggTexture::FT_linear_mipmap_nearest:
      case EggTexture::FT_nearest_mipmap_linear:
      case EggTexture::FT_linear_mipmap_linear:
        out << " mipmap";
        break;

      default:
        break;
  }

  if(_properties._anisotropic_degree>1) {
        out << " aniso " << _properties._anisotropic_degree;
  }

  out << "\n";
}


////////////////////////////////////////////////////////////////////
//     Function: TextureReference::get_uv_range
//       Access: Private
//  Description: Checks the geometry in the egg file to see what range
//               of UV's are requested for this particular texture
//               reference.
//
//               If pal->_remap_uv is not RU_never, this will also
//               attempt to remap the UV's found so that the midpoint
//               lies in the unit square (0,0) - (1,1), in the hopes
//               of maximizing overlap of UV coordinates between
//               different polygons.  However, the hypothetical
//               translations are not actually applied to the egg file
//               at this point (because we might decide not to place
//               the texture in a palette); they will actually be
//               applied when update_uv_range(), below, is called
//               later.
////////////////////////////////////////////////////////////////////
void TextureReference::
get_uv_range(EggGroupNode *group, Palettizer::RemapUV remap) {
  if (group->is_of_type(EggGroup::get_class_type())) {
    EggGroup *egg_group;
    DCAST_INTO_V(egg_group, group);

    if (egg_group->get_dart_type() != EggGroup::DT_none) {
      // If it's a character, we might change the kind of remapping we
      // do.
      remap = pal->_remap_char_uv;
    }
  }

  bool group_any_uvs = false;
  TexCoordd group_min_uv, group_max_uv;

  EggGroupNode::iterator ci;
  for (ci = group->begin(); ci != group->end(); ci++) {
    EggNode *child = (*ci);
    if (child->is_of_type(EggNurbsSurface::get_class_type())) {
      EggNurbsSurface *nurbs = DCAST(EggNurbsSurface, child);
      if (nurbs->has_texture() && nurbs->get_texture() == _egg_tex) {
        // Here's a NURBS surface that references the texture.  Unlike
        // other kinds of geometries, NURBS don't store UV's; they're
        // implicit in the surface.  NURBS UV's will always run in the
        // range (0,0) - (1,1).  However, we do need to apply the
        // texture matrix.

        // We also don't count the NURBS surfaces in with the group's
        // UV's, because we can't adjust the UV's on a NURBS, so
        // counting them up would be misleading (the reason we count
        // up the group UV's is so we can consider adjusting them
        // later).  Instead, we just accumulate the NURBS UV's
        // directly into our total.

        static const int num_nurbs_uvs = 4;
        static TexCoordd nurbs_uvs[num_nurbs_uvs] = {
          TexCoordd(0.0, 0.0),
          TexCoordd(0.0, 1.0),
          TexCoordd(1.0, 1.0),
          TexCoordd(1.0, 0.0)
        };

        for (int i = 0; i < num_nurbs_uvs; i++) {
          TexCoordd uv = nurbs_uvs[i] * _tex_mat;
          collect_uv(_any_uvs, _min_uv, _max_uv, uv, uv);
        }
      }

    } else if (child->is_of_type(EggPrimitive::get_class_type())) {
      EggPrimitive *geom = DCAST(EggPrimitive, child);
      if (geom->has_texture() && geom->get_texture() == _egg_tex) {
        // Here's a piece of geometry that references this texture.
        // Walk through its vertices and get its UV's.
        TexCoordd geom_min_uv, geom_max_uv;

        if (get_geom_uvs(geom, geom_min_uv, geom_max_uv)) {
          if (remap == Palettizer::RU_poly) {
            LVector2d trans = translate_uv(geom_min_uv, geom_max_uv);
            geom_min_uv += trans;
            geom_max_uv += trans;
          }
          collect_uv(group_any_uvs, group_min_uv, group_max_uv,
                     geom_min_uv, geom_max_uv);
        }
      }

    } else if (child->is_of_type(EggGroupNode::get_class_type())) {
      EggGroupNode *cg = DCAST(EggGroupNode, child);
      get_uv_range(cg, remap);
    }
  }

  if (group_any_uvs) {
    if (remap == Palettizer::RU_group) {
      LVector2d trans = translate_uv(group_min_uv, group_max_uv);
      group_min_uv += trans;
      group_max_uv += trans;
    }
    collect_uv(_any_uvs, _min_uv, _max_uv, group_min_uv, group_max_uv);
  }
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::update_uv_range
//       Access: Private
//  Description: Actually applies the UV translates that were assumed
//               in the previous call to get_uv_range().
////////////////////////////////////////////////////////////////////
void TextureReference::
update_uv_range(EggGroupNode *group, Palettizer::RemapUV remap) {
  if (group->is_of_type(EggGroup::get_class_type())) {
    EggGroup *egg_group;
    DCAST_INTO_V(egg_group, group);

    if (egg_group->get_dart_type() != EggGroup::DT_none) {
      // If it's a character, we might change the kind of remapping we
      // do.
      remap = pal->_remap_char_uv;
    }
  }

  bool group_any_uvs = false;
  TexCoordd group_min_uv, group_max_uv;

  EggGroupNode::iterator ci;
  for (ci = group->begin(); ci != group->end(); ci++) {
    EggNode *child = (*ci);
    if (child->is_of_type(EggNurbsSurface::get_class_type())) {
      // We do nothing at this point for a Nurbs.  Nothing we can do
      // about these things.

    } else if (child->is_of_type(EggPrimitive::get_class_type())) {
      if (remap != Palettizer::RU_never) {
        EggPrimitive *geom = DCAST(EggPrimitive, child);
        if (geom->has_texture() && geom->get_texture() == _egg_tex) {
          TexCoordd geom_min_uv, geom_max_uv;

          if (get_geom_uvs(geom, geom_min_uv, geom_max_uv)) {
            if (remap == Palettizer::RU_poly) {
              LVector2d trans = translate_uv(geom_min_uv, geom_max_uv);
              trans = trans * _inv_tex_mat;
              if (!trans.almost_equal(LVector2d::zero())) {
                translate_geom_uvs(geom, trans);
              }
            } else {
              collect_uv(group_any_uvs, group_min_uv, group_max_uv,
                         geom_min_uv, geom_max_uv);
            }
          }
        }
      }

    } else if (child->is_of_type(EggGroupNode::get_class_type())) {
      EggGroupNode *cg = DCAST(EggGroupNode, child);
      update_uv_range(cg, remap);
    }
  }

  if (group_any_uvs && remap == Palettizer::RU_group) {
    LVector2d trans = translate_uv(group_min_uv, group_max_uv);
    trans = trans * _inv_tex_mat;
    if (!trans.almost_equal(LVector2d::zero())) {
      for (ci = group->begin(); ci != group->end(); ci++) {
        EggNode *child = (*ci);
        if (child->is_of_type(EggPrimitive::get_class_type())) {
          EggPrimitive *geom = DCAST(EggPrimitive, child);
          if (geom->has_texture() && geom->get_texture() == _egg_tex) {
            translate_geom_uvs(geom, trans);
          }
        }
      }
    }
  }
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::get_geom_uvs
//       Access: Private
//  Description: Determines the minimum and maximum UV range for a
//               particular primitive.  Returns true if it has any
//               UV's, false otherwise.
////////////////////////////////////////////////////////////////////
bool TextureReference::
get_geom_uvs(EggPrimitive *geom,
             TexCoordd &geom_min_uv, TexCoordd &geom_max_uv) {
  bool geom_any_uvs = false;

  EggPrimitive::iterator pi;
  for (pi = geom->begin(); pi != geom->end(); ++pi) {
    EggVertex *vtx = (*pi);
    if (vtx->has_uv()) {
      TexCoordd uv = vtx->get_uv() * _tex_mat;
      collect_uv(geom_any_uvs, geom_min_uv, geom_max_uv, uv, uv);
    }
  }

  return geom_any_uvs;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::translate_geom_uvs
//       Access: Private
//  Description: Applies the indicated translation to each UV in the
//               primitive.
////////////////////////////////////////////////////////////////////
void TextureReference::
translate_geom_uvs(EggPrimitive *geom, const TexCoordd &trans) const {
  EggPrimitive::iterator pi;
  for (pi = geom->begin(); pi != geom->end(); ++pi) {
    EggVertex *vtx = (*pi);
    if (vtx->has_uv()) {
      EggVertex vtx_copy(*vtx);
      vtx_copy.set_uv(vtx_copy.get_uv() + trans);
      EggVertex *new_vtx = vtx->get_pool()->create_unique_vertex(vtx_copy);

      if (new_vtx->gref_size() != vtx->gref_size()) {
        new_vtx->copy_grefs_from(*vtx);
      }

      geom->replace(pi, new_vtx);
    }
  }
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::collect_uv
//       Access: Private, Static
//  Description: Updates any_uvs, min_uv, and max_uv with the
//               indicated min and max UV's already determined.
////////////////////////////////////////////////////////////////////
void TextureReference::
collect_uv(bool &any_uvs, TexCoordd &min_uv, TexCoordd &max_uv,
           const TexCoordd &got_min_uv, const TexCoordd &got_max_uv) {
  if (any_uvs) {
    min_uv.set(min(min_uv[0], got_min_uv[0]),
               min(min_uv[1], got_min_uv[1]));
    max_uv.set(max(max_uv[0], got_max_uv[0]),
               max(max_uv[1], got_max_uv[1]));
  } else {
    // The first UV.
    min_uv = got_min_uv;
    max_uv = got_max_uv;
    any_uvs = true;
  }
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::translate_uv
//       Access: Private, Static
//  Description: Returns the needed adjustment to translate the given
//               bounding box so that its center lies in the unit
//               square (0,0) - (1,1).
////////////////////////////////////////////////////////////////////
LVector2d TextureReference::
translate_uv(const TexCoordd &min_uv, const TexCoordd &max_uv) {
  TexCoordd center = (min_uv + max_uv) / 2;
  return LVector2d(-floor(center[0]), -floor(center[1]));
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::register_with_read_factory
//       Access: Public, Static
//  Description: Registers the current object as something that can be
//               read from a Bam file.
////////////////////////////////////////////////////////////////////
void TextureReference::
register_with_read_factory() {
  BamReader::get_factory()->
    register_factory(get_class_type(), make_TextureReference);
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::write_datagram
//       Access: Public, Virtual
//  Description: Fills the indicated datagram up with a binary
//               representation of the current object, in preparation
//               for writing to a Bam file.
////////////////////////////////////////////////////////////////////
void TextureReference::
write_datagram(BamWriter *writer, Datagram &datagram) {
  TypedWritable::write_datagram(writer, datagram);
  writer->write_pointer(datagram, _egg_file);

  // We don't write _egg_tex or _egg_data; that's specific to the
  // session.

  datagram.add_string(_tref_name);

  _tex_mat.write_datagram(datagram);
  _inv_tex_mat.write_datagram(datagram);

  writer->write_pointer(datagram, _source_texture);
  writer->write_pointer(datagram, _placement);

  datagram.add_bool(_uses_alpha);
  datagram.add_bool(_any_uvs);
  datagram.add_float64(_min_uv[0]);
  datagram.add_float64(_min_uv[1]);
  datagram.add_float64(_max_uv[0]);
  datagram.add_float64(_max_uv[1]);
  datagram.add_int32((int)_wrap_u);
  datagram.add_int32((int)_wrap_v);
  _properties.write_datagram(writer, datagram);
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::complete_pointers
//       Access: Public, Virtual
//  Description: Called after the object is otherwise completely read
//               from a Bam file, this function's job is to store the
//               pointers that were retrieved from the Bam file for
//               each pointer object written.  The return value is the
//               number of pointers processed from the list.
////////////////////////////////////////////////////////////////////
int TextureReference::
complete_pointers(TypedWritable **p_list, BamReader *manager) {
  int pi = TypedWritable::complete_pointers(p_list, manager);

  if (p_list[pi] != (TypedWritable *)NULL) {
    DCAST_INTO_R(_egg_file, p_list[pi], pi);
  }
  pi++;

  if (p_list[pi] != (TypedWritable *)NULL) {
    DCAST_INTO_R(_source_texture, p_list[pi], pi);
  }
  pi++;

  if (p_list[pi] != (TypedWritable *)NULL) {
    DCAST_INTO_R(_placement, p_list[pi], pi);
  }
  pi++;

  pi += _properties.complete_pointers(p_list + pi, manager);

  return pi;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::make_TextureReference
//       Access: Protected
//  Description: This method is called by the BamReader when an object
//               of this type is encountered in a Bam file; it should
//               allocate and return a new object with all the data
//               read.
////////////////////////////////////////////////////////////////////
TypedWritable* TextureReference::
make_TextureReference(const FactoryParams &params) {
  TextureReference *me = new TextureReference;
  DatagramIterator scan;
  BamReader *manager;

  parse_params(params, scan, manager);
  me->fillin(scan, manager);
  return me;
}

////////////////////////////////////////////////////////////////////
//     Function: TextureReference::fillin
//       Access: Protected
//  Description: Reads the binary data from the given datagram
//               iterator, which was written by a previous call to
//               write_datagram().
////////////////////////////////////////////////////////////////////
void TextureReference::
fillin(DatagramIterator &scan, BamReader *manager) {
  TypedWritable::fillin(scan, manager);
  manager->read_pointer(scan);  // _egg_file

  if (Palettizer::_read_pi_version >= 11) {
    _tref_name = scan.get_string();
  }

  _tex_mat.read_datagram(scan);
  _inv_tex_mat.read_datagram(scan);

  manager->read_pointer(scan);  // _source_texture
  manager->read_pointer(scan);  // _placement

  _uses_alpha = scan.get_bool();
  _any_uvs = scan.get_bool();
  _min_uv[0] = scan.get_float64();
  _min_uv[1] = scan.get_float64();
  _max_uv[0] = scan.get_float64();
  _max_uv[1] = scan.get_float64();
  _wrap_u = (EggTexture::WrapMode)scan.get_int32();
  _wrap_v = (EggTexture::WrapMode)scan.get_int32();
  _properties.fillin(scan, manager);
}