---

panda/src/egg2pg/eggLoader.cxx

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// Filename: EggLoader.cxx
// Created by:  drose (26Feb02)
//
////////////////////////////////////////////////////////////////////
//
// 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 "pandabase.h"

#include "eggLoader.h"
#include "config_egg2pg.h"
#include "nodePath.h"
#include "renderState.h"
#include "transformState.h"
#include "textureAttrib.h"
#include "textureApplyAttrib.h"
#include "texturePool.h"
#include "billboardEffect.h"
#include "cullFaceAttrib.h"
#include "cullBinAttrib.h"
#include "transparencyAttrib.h"
#include "decalEffect.h"
#include "depthTestAttrib.h"
#include "depthWriteAttrib.h"
#include "materialAttrib.h"
#include "materialPool.h"
#include "geomNode.h"
#include "sequenceNode.h"
#include "switchNode.h"
#include "lodNode.h"
#include "modelNode.h"
#include "modelRoot.h"
#include "string_utils.h"
#include "eggPrimitive.h"
#include "eggPoint.h"
#include "eggTextureCollection.h"
#include "eggNurbsCurve.h"
#include "eggGroupNode.h"
#include "eggGroup.h"
#include "eggPolygon.h"
#include "eggBin.h"
#include "eggTable.h"
#include "eggBinner.h"
#include "eggVertexPool.h"
#include "characterMaker.h"
#include "character.h"
#include "animBundleMaker.h"
#include "animBundleNode.h"
#include "selectiveChildNode.h"
#include "collisionNode.h"
#include "collisionSphere.h"
#include "collisionPlane.h"
#include "collisionPolygon.h"
#include "parametricCurve.h"
#include "nurbsCurve.h"
#include "classicNurbsCurve.h"
#include "nurbsCurveInterface.h"

#include <ctype.h>
#include <algorithm>

// This class is used in make_node(EggBin *) to sort LOD instances in
// order by switching distance.
class LODInstance {
public:
  LODInstance(EggNode *egg_node);
  bool operator < (const LODInstance &other) const {
    return _d->_switch_in < other._d->_switch_in;
  }

  EggNode *_egg_node;
  const EggSwitchConditionDistance *_d;
};

LODInstance::
LODInstance(EggNode *egg_node) {
  nassertv(egg_node != NULL);
  _egg_node = egg_node;

  // We expect this egg node to be an EggGroup with an LOD
  // specification.  That's what the EggBinner collected together,
  // after all.
  EggGroup *egg_group = DCAST(EggGroup, egg_node);
  nassertv(egg_group->has_lod());
  const EggSwitchCondition &sw = egg_group->get_lod();

  // For now, this is the only kind of switch condition there is.
  _d = DCAST(EggSwitchConditionDistance, &sw);
}


////////////////////////////////////////////////////////////////////
//     Function: EggLoader::Constructor
//       Access: Public
//  Description:
////////////////////////////////////////////////////////////////////
EggLoader::
EggLoader() {
  // We need to enforce whatever coordinate system the user asked for.
  _data.set_coordinate_system(egg_coordinate_system);
  _error = false;
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::Constructor
//       Access: Public
//  Description:
////////////////////////////////////////////////////////////////////
EggLoader::
EggLoader(const EggData &data) :
  _data(data)
{
  _error = false;
}


////////////////////////////////////////////////////////////////////
//     Function: EggLoader::build_graph
//       Access: Public
//  Description:
////////////////////////////////////////////////////////////////////
void EggLoader::
build_graph() {
  _deferred_nodes.clear();

  // First, bin up the LOD nodes.
  EggBinner binner;
  binner.make_bins(&_data);

  // Then load up all of the textures.
  load_textures();

  // Now build up the scene graph.
  _root = new ModelRoot(_data.get_egg_filename().get_basename());
  make_node(&_data, _root);
  _builder.build();

  reparent_decals();

  apply_deferred_nodes(_root, DeferredNodeProperty());
}


////////////////////////////////////////////////////////////////////
//     Function: EggLoader::reparent_decals
//       Access: Public
//  Description: For each node representing a decal base geometry
//               (i.e. a node corresponding to an EggGroup with the
//               decal flag set), move all of its nested geometry
//               directly below the GeomNode representing the group.
////////////////////////////////////////////////////////////////////
void EggLoader::
reparent_decals() {
  Decals::const_iterator di;
  for (di = _decals.begin(); di != _decals.end(); ++di) {
    PandaNode *node = (*di);
    nassertv(node != (PandaNode *)NULL);

    // The NodePath interface is best for this.
    NodePath parent(node);

    // First, search for the GeomNode.
    NodePath geom_parent;
    int num_children = parent.get_num_children();
    for (int i = 0; i < num_children; i++) {
      NodePath child = parent.get_child(i);

      if (child.node()->is_of_type(GeomNode::get_class_type())) {
        if (!geom_parent.is_empty()) {
          // Oops, too many GeomNodes.
          egg2pg_cat.error()
            << "Decal onto " << parent.node()->get_name()
            << " uses base geometry with multiple GeomNodes.\n";
          _error = true;
        }
        geom_parent = child;
      }
    }

    if (geom_parent.is_empty()) {
      // No children were GeomNodes.
      egg2pg_cat.error()
        << "Ignoring decal onto " << parent.node()->get_name()
        << "; no geometry within group.\n";
      _error = true;
    } else {
      // Now reparent all of the non-GeomNodes to this node.  We have
      // to be careful so we don't get lost as we self-modify this
      // list.
      int i = 0;
      while (i < num_children) {
        NodePath child = parent.get_child(i);

        if (child.node()->is_of_type(GeomNode::get_class_type())) {
          i++;
        } else {
          child.reparent_to(geom_parent);
          num_children--;
        }
      }

      // Finally, set the DecalEffect on the base geometry.
      geom_parent.node()->set_effect(DecalEffect::make());
    }
  }
}


////////////////////////////////////////////////////////////////////
//     Function: EggLoader::make_nonindexed_primitive
//       Access: Public
//  Description:
////////////////////////////////////////////////////////////////////
void EggLoader::
make_nonindexed_primitive(EggPrimitive *egg_prim, PandaNode *parent,
                          const LMatrix4d *transform) {
  BuilderBucket bucket;
  setup_bucket(bucket, parent, egg_prim);

  LMatrix4d mat;

  if (transform != NULL) {
    mat = (*transform);
  } else {
    mat = egg_prim->get_vertex_to_node();
  }

  BuilderPrim bprim;
  bprim.set_type(BPT_poly);
  if (egg_prim->is_of_type(EggPoint::get_class_type())) {
    bprim.set_type(BPT_point);
  }

  if (egg_prim->has_normal()) {
    Normald norm = egg_prim->get_normal() * mat;
    norm.normalize();
    bprim.set_normal(LCAST(float, norm));
  }
  if (egg_prim->has_color() && !egg_false_color) {
    bprim.set_color(egg_prim->get_color());
  }

  bool has_vert_color = true;
  EggPrimitive::const_iterator vi;
  for (vi = egg_prim->begin(); vi != egg_prim->end(); ++vi) {
    EggVertex *egg_vert = *vi;
    if (egg_vert->get_num_dimensions() != 3) {
      egg2pg_cat.error()
        << "Vertex " << egg_vert->get_pool()->get_name() 
        << ":" << egg_vert->get_index() << " has dimension " 
        << egg_vert->get_num_dimensions() << "\n";
    } else {
      BuilderVertex bvert(LCAST(float, egg_vert->get_pos3() * mat));

      if (egg_vert->has_normal()) {
        Normald norm = egg_vert->get_normal() * mat;
        norm.normalize();
        bvert.set_normal(LCAST(float, norm));
      }
      if (egg_vert->has_color() && !egg_false_color) {
        bvert.set_color(egg_vert->get_color());
      } else {
        // If any vertex doesn't have a color, we can't use any of the
        // vertex colors.
        has_vert_color = false;
      }
      if (egg_vert->has_uv()) {
        TexCoordd uv = egg_vert->get_uv();
        if (egg_prim->has_texture() &&
            egg_prim->get_texture()->has_transform()) {
          // If we have a texture matrix, apply it.
          uv = uv * egg_prim->get_texture()->get_transform();
        }
        bvert.set_texcoord(LCAST(float, uv));
      }
    
      bprim.add_vertex(bvert);
    }
  }

  // Finally, if the primitive didn't have a color, and it didn't have
  // vertex color, make it white.
  if (!egg_prim->has_color() && !has_vert_color && !egg_false_color) {
    bprim.set_color(Colorf(1.0, 1.0, 1.0, 1.0));
  }

  _builder.add_prim(bucket, bprim);
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::make_indexed_primitive
//       Access: Public
//  Description:
////////////////////////////////////////////////////////////////////
void EggLoader::
make_indexed_primitive(EggPrimitive *egg_prim, PandaNode *parent,
                       const LMatrix4d *transform,
                       ComputedVerticesMaker &_comp_verts_maker) {
  BuilderBucket bucket;
  setup_bucket(bucket, parent, egg_prim);

  bucket.set_coords(_comp_verts_maker._coords);
  bucket.set_normals(_comp_verts_maker._norms);
  bucket.set_texcoords(_comp_verts_maker._texcoords);
  bucket.set_colors(_comp_verts_maker._colors);

  LMatrix4d mat;

  if (transform != NULL) {
    mat = (*transform);
  } else {
    mat = egg_prim->get_vertex_to_node();
  }

  BuilderPrimI bprim;
  bprim.set_type(BPT_poly);
  if (egg_prim->is_of_type(EggPoint::get_class_type())) {
    bprim.set_type(BPT_point);
  }

  if (egg_prim->has_normal()) {
    // Define the transform space of the polygon normal.  This will be
    // the average of all the vertex transform spaces.
    _comp_verts_maker.begin_new_space();
    EggPrimitive::const_iterator vi;
    for (vi = egg_prim->begin(); vi != egg_prim->end(); ++vi) {
      EggVertex *egg_vert = *vi;
      _comp_verts_maker.add_vertex_joints(egg_vert, egg_prim);
    }
    _comp_verts_maker.mark_space();

    int nindex =
      _comp_verts_maker.add_normal(egg_prim->get_normal(),
                                   egg_prim->_dnormals, mat);

    bprim.set_normal(nindex);
  }

  if (egg_prim->has_color() && !egg_false_color) {
    int cindex =
      _comp_verts_maker.add_color(egg_prim->get_color(),
                                  egg_prim->_drgbas);
    bprim.set_color(cindex);
  }

  bool has_vert_color = true;
  EggPrimitive::const_iterator vi;
  for (vi = egg_prim->begin(); vi != egg_prim->end(); ++vi) {
    EggVertex *egg_vert = *vi;

    if (egg_vert->get_num_dimensions() != 3) {
      egg2pg_cat.error()
        << "Vertex " << egg_vert->get_pool()->get_name() 
        << ":" << egg_vert->get_index() << " has dimension " 
        << egg_vert->get_num_dimensions() << "\n";
    } else {
      // Set up the ComputedVerticesMaker for the coordinate space of
      // the vertex.
      _comp_verts_maker.begin_new_space();
      _comp_verts_maker.add_vertex_joints(egg_vert, egg_prim);
      _comp_verts_maker.mark_space();
      
      int vindex =
        _comp_verts_maker.add_vertex(egg_vert->get_pos3(),
                                     egg_vert->_dxyzs, mat);
      BuilderVertexI bvert(vindex);
      
      if (egg_vert->has_normal()) {
        int nindex =
          _comp_verts_maker.add_normal(egg_vert->get_normal(),
                                       egg_vert->_dnormals,
                                       mat);
        bvert.set_normal(nindex);
      }
      
      if (egg_vert->has_color() && !egg_false_color) {
        int cindex =
          _comp_verts_maker.add_color(egg_vert->get_color(),
                                      egg_vert->_drgbas);
        bvert.set_color(cindex);
      } else {
        // If any vertex doesn't have a color, we can't use any of the
        // vertex colors.
        has_vert_color = false;
      }

      if (egg_vert->has_uv()) {
        TexCoordd uv = egg_vert->get_uv();
        LMatrix3d mat;
        
        if (egg_prim->has_texture() &&
            egg_prim->get_texture()->has_transform()) {
          // If we have a texture matrix, apply it.
          mat = egg_prim->get_texture()->get_transform();
        } else {
          mat = LMatrix3d::ident_mat();
        }
        
        int tindex =
          _comp_verts_maker.add_texcoord(uv, egg_vert->_duvs, mat);
        bvert.set_texcoord(tindex);
      }
      
      bprim.add_vertex(bvert);
    }
  }

  // Finally, if the primitive didn't have a color, and it didn't have
  // vertex color, make it white.
  if (!egg_prim->has_color() && !has_vert_color && !egg_false_color) {
    int cindex =
      _comp_verts_maker.add_color(Colorf(1.0, 1.0, 1.0, 1.0),
                                  EggMorphColorList());
    bprim.set_color(cindex);
  }

  _builder.add_prim(bucket, bprim);
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::load_textures
//       Access: Private
//  Description:
////////////////////////////////////////////////////////////////////
void EggLoader::
load_textures() {
  // First, collect all the textures that are referenced.
  EggTextureCollection tc;
  tc.find_used_textures(&_data);

  // Collapse the textures down by filename only.  Should we also
  // differentiate by attributes?  Maybe.
  EggTextureCollection::TextureReplacement replace;
  tc.collapse_equivalent_textures(EggTexture::E_complete_filename,
                                  replace);

  EggTextureCollection::iterator ti;
  for (ti = tc.begin(); ti != tc.end(); ++ti) {
    PT(EggTexture) egg_tex = (*ti);

    TextureDef def;
    if (load_texture(def, egg_tex)) {
      // Now associate the pointers, so we'll be able to look up the
      // Texture pointer given an EggTexture pointer, later.
      _textures[egg_tex] = def;
    }
  }

  // Finally, associate all of the removed texture references back to
  // the same pointers as the others.
  EggTextureCollection::TextureReplacement::const_iterator ri;
  for (ri = replace.begin(); ri != replace.end(); ++ri) {
    PT(EggTexture) orig = (*ri).first;
    PT(EggTexture) repl = (*ri).second;

    _textures[orig] = _textures[repl];
  }
}


////////////////////////////////////////////////////////////////////
//     Function: EggLoader::load_texture
//       Access: Private
//  Description:
////////////////////////////////////////////////////////////////////
bool EggLoader::
load_texture(TextureDef &def, const EggTexture *egg_tex) {
  // Check to see if we should reduce the number of channels in
  // the texture.
  int wanted_channels = 0;
  bool wanted_alpha = false;
  switch (egg_tex->get_format()) {
  case EggTexture::F_red:
  case EggTexture::F_green:
  case EggTexture::F_blue:
  case EggTexture::F_alpha:
  case EggTexture::F_luminance:
    wanted_channels = 1;
    wanted_alpha = false;
    break;

  case EggTexture::F_luminance_alpha:
  case EggTexture::F_luminance_alphamask:
    wanted_channels = 2;
    wanted_alpha = true;
    break;

  case EggTexture::F_rgb:
  case EggTexture::F_rgb12:
  case EggTexture::F_rgb8:
  case EggTexture::F_rgb5:
  case EggTexture::F_rgb332:
    wanted_channels = 3;
    wanted_alpha = false;
    break;

  case EggTexture::F_rgba:
  case EggTexture::F_rgbm:
  case EggTexture::F_rgba12:
  case EggTexture::F_rgba8:
  case EggTexture::F_rgba4:
  case EggTexture::F_rgba5:
    wanted_channels = 4;
    wanted_alpha = true;
    break;

  case EggTexture::F_unspecified:
    break;
  }

  Texture *tex;
  if (egg_tex->has_alpha_filename() && wanted_alpha) {
    tex = TexturePool::load_texture(egg_tex->get_fullpath(),
                                    egg_tex->get_alpha_fullpath(),
                                    wanted_channels,
                                    egg_tex->get_alpha_file_channel());
  } else {
    tex = TexturePool::load_texture(egg_tex->get_fullpath(),
                                    wanted_channels);
  }
  if (tex == (Texture *)NULL) {
    return false;
  }

  // Record the original filenames in the textures (as loaded from the
  // egg file).  These filenames will be written back to the bam file
  // if the bam file is written out.
  tex->set_filename(egg_tex->get_filename());
  if (egg_tex->has_alpha_filename() && wanted_alpha) {
    tex->set_alpha_filename(egg_tex->get_alpha_filename());
  }

  apply_texture_attributes(tex, egg_tex);
  CPT(RenderAttrib) apply = get_texture_apply_attributes(egg_tex);

  def._texture = TextureAttrib::make(tex);
  def._apply = apply;

  return true;
}


////////////////////////////////////////////////////////////////////
//     Function: EggLoader::apply_texture_attributes
//       Access: Private
//  Description:
////////////////////////////////////////////////////////////////////
void EggLoader::
apply_texture_attributes(Texture *tex, const EggTexture *egg_tex) {
  switch (egg_tex->determine_wrap_u()) {
  case EggTexture::WM_repeat:
    tex->set_wrapu(Texture::WM_repeat);
    break;

  case EggTexture::WM_clamp:
    if (egg_ignore_clamp) {
      egg2pg_cat.warning()
        << "Ignoring clamp request\n";
      tex->set_wrapu(Texture::WM_repeat);
    } else {
      tex->set_wrapu(Texture::WM_clamp);
    }
    break;

  case EggTexture::WM_unspecified:
    break;

  default:
    egg2pg_cat.warning()
      << "Unexpected texture wrap flag: "
      << (int)egg_tex->determine_wrap_u() << "\n";
  }

  switch (egg_tex->determine_wrap_v()) {
  case EggTexture::WM_repeat:
    tex->set_wrapv(Texture::WM_repeat);
    break;

  case EggTexture::WM_clamp:
    if (egg_ignore_clamp) {
      egg2pg_cat.warning()
        << "Ignoring clamp request\n";
      tex->set_wrapv(Texture::WM_repeat);
    } else {
      tex->set_wrapv(Texture::WM_clamp);
    }
    break;

  case EggTexture::WM_unspecified:
    break;

  default:
    egg2pg_cat.warning()
      << "Unexpected texture wrap flag: "
      << (int)egg_tex->determine_wrap_v() << "\n";
  }

  switch (egg_tex->get_minfilter()) {
  case EggTexture::FT_nearest:
    tex->set_minfilter(Texture::FT_nearest);
    break;

  case EggTexture::FT_linear:
    if (egg_ignore_filters) {
      egg2pg_cat.warning()
        << "Ignoring minfilter request\n";
      tex->set_minfilter(Texture::FT_nearest);
    } else {
      tex->set_minfilter(Texture::FT_linear);
    }
    break;

  case EggTexture::FT_nearest_mipmap_nearest:
    if (egg_ignore_filters) {
      egg2pg_cat.warning()
        << "Ignoring minfilter request\n";
      tex->set_minfilter(Texture::FT_nearest);
    } else if (egg_ignore_mipmaps) {
      egg2pg_cat.warning()
        << "Ignoring mipmap request\n";
      tex->set_minfilter(Texture::FT_nearest);
    } else {
      tex->set_minfilter(Texture::FT_nearest_mipmap_nearest);
    }
    break;

  case EggTexture::FT_linear_mipmap_nearest:
    if (egg_ignore_filters) {
      egg2pg_cat.warning()
        << "Ignoring minfilter request\n";
      tex->set_minfilter(Texture::FT_nearest);
    } else if (egg_ignore_mipmaps) {
      egg2pg_cat.warning()
        << "Ignoring mipmap request\n";
      tex->set_minfilter(Texture::FT_linear);
    } else {
      tex->set_minfilter(Texture::FT_linear_mipmap_nearest);
    }
    break;

  case EggTexture::FT_nearest_mipmap_linear:
    if (egg_ignore_filters) {
      egg2pg_cat.warning()
        << "Ignoring minfilter request\n";
      tex->set_minfilter(Texture::FT_nearest);
    } else if (egg_ignore_mipmaps) {
      egg2pg_cat.warning()
        << "Ignoring mipmap request\n";
      tex->set_minfilter(Texture::FT_nearest);
    } else {
      tex->set_minfilter(Texture::FT_nearest_mipmap_linear);
    }
    break;

  case EggTexture::FT_linear_mipmap_linear:
    if (egg_ignore_filters) {
      egg2pg_cat.warning()
        << "Ignoring minfilter request\n";
      tex->set_minfilter(Texture::FT_nearest);
    } else if (egg_ignore_mipmaps) {
      egg2pg_cat.warning()
        << "Ignoring mipmap request\n";
      tex->set_minfilter(Texture::FT_linear);
    } else {
      tex->set_minfilter(Texture::FT_linear_mipmap_linear);
    }
    break;

  case EggTexture::FT_unspecified:
    // Default is bilinear, unless egg_ignore_filters is specified.
    if (egg_ignore_filters) {
      tex->set_minfilter(Texture::FT_nearest);
    } else {
      tex->set_minfilter(Texture::FT_linear);
    }
  }

  switch (egg_tex->get_magfilter()) {
  case EggTexture::FT_nearest:
  case EggTexture::FT_nearest_mipmap_nearest:
  case EggTexture::FT_nearest_mipmap_linear:
    tex->set_magfilter(Texture::FT_nearest);
    break;

  case EggTexture::FT_linear:
  case EggTexture::FT_linear_mipmap_nearest:
  case EggTexture::FT_linear_mipmap_linear:
    if (egg_ignore_filters) {
      egg2pg_cat.warning()
        << "Ignoring magfilter request\n";
      tex->set_magfilter(Texture::FT_nearest);
    } else {
      tex->set_magfilter(Texture::FT_linear);
    }
    break;

  case EggTexture::FT_unspecified:
    // Default is bilinear, unless egg_ignore_filters is specified.
    if (egg_ignore_filters) {
      tex->set_magfilter(Texture::FT_nearest);
    } else {
      tex->set_magfilter(Texture::FT_linear);
    }
  }

  if (egg_tex->has_anisotropic_degree()) {
    tex->set_anisotropic_degree(egg_tex->get_anisotropic_degree());
  }

  if (tex->_pbuffer->get_num_components() == 1) {
    switch (egg_tex->get_format()) {
    case EggTexture::F_red:
      tex->_pbuffer->set_format(PixelBuffer::F_red);
      break;
    case EggTexture::F_green:
      tex->_pbuffer->set_format(PixelBuffer::F_green);
      break;
    case EggTexture::F_blue:
      tex->_pbuffer->set_format(PixelBuffer::F_blue);
      break;
    case EggTexture::F_alpha:
      tex->_pbuffer->set_format(PixelBuffer::F_alpha);
      break;
    case EggTexture::F_luminance:
      tex->_pbuffer->set_format(PixelBuffer::F_luminance);
      break;

    case EggTexture::F_unspecified:
      break;

    default:
      egg2pg_cat.warning()
        << "Ignoring inappropriate format " << egg_tex->get_format()
        << " for 1-component texture " << egg_tex->get_name() << "\n";
    }

  } else if (tex->_pbuffer->get_num_components() == 2) {
    switch (egg_tex->get_format()) {
    case EggTexture::F_luminance_alpha:
      tex->_pbuffer->set_format(PixelBuffer::F_luminance_alpha);
      break;

    case EggTexture::F_luminance_alphamask:
      tex->_pbuffer->set_format(PixelBuffer::F_luminance_alphamask);
      break;

    case EggTexture::F_unspecified:
      break;

    default:
      egg2pg_cat.warning()
        << "Ignoring inappropriate format " << egg_tex->get_format()
        << " for 2-component texture " << egg_tex->get_name() << "\n";
    }

  } else if (tex->_pbuffer->get_num_components() == 3) {
    switch (egg_tex->get_format()) {
    case EggTexture::F_rgb:
      tex->_pbuffer->set_format(PixelBuffer::F_rgb);
      break;
    case EggTexture::F_rgb12:
      if (tex->_pbuffer->get_component_width() >= 2) {
        // Only do this if the component width supports it.
        tex->_pbuffer->set_format(PixelBuffer::F_rgb12);
      } else {
        egg2pg_cat.warning()
          << "Ignoring inappropriate format " << egg_tex->get_format()
          << " for 8-bit texture " << egg_tex->get_name() << "\n";
      }
      break;
    case EggTexture::F_rgb8:
    case EggTexture::F_rgba8:
      // We'll quietly accept RGBA8 for a 3-component texture, since
      // flt2egg generates these for 3-component as well as for
      // 4-component textures.
      tex->_pbuffer->set_format(PixelBuffer::F_rgb8);
      break;
    case EggTexture::F_rgb5:
      tex->_pbuffer->set_format(PixelBuffer::F_rgb5);
      break;
    case EggTexture::F_rgb332:
      tex->_pbuffer->set_format(PixelBuffer::F_rgb332);
      break;

    case EggTexture::F_unspecified:
      break;

    default:
      egg2pg_cat.warning()
        << "Ignoring inappropriate format " << egg_tex->get_format()
        << " for 3-component texture " << egg_tex->get_name() << "\n";
    }

  } else if (tex->_pbuffer->get_num_components() == 4) {
    switch (egg_tex->get_format()) {
    case EggTexture::F_rgba:
      tex->_pbuffer->set_format(PixelBuffer::F_rgba);
      break;
    case EggTexture::F_rgbm:
      tex->_pbuffer->set_format(PixelBuffer::F_rgbm);
      break;
    case EggTexture::F_rgba12:
      if (tex->_pbuffer->get_component_width() >= 2) {
        // Only do this if the component width supports it.
        tex->_pbuffer->set_format(PixelBuffer::F_rgba12);
      } else {
        egg2pg_cat.warning()
          << "Ignoring inappropriate format " << egg_tex->get_format()
          << " for 8-bit texture " << egg_tex->get_name() << "\n";
      }
      break;
    case EggTexture::F_rgba8:
      tex->_pbuffer->set_format(PixelBuffer::F_rgba8);
      break;
    case EggTexture::F_rgba4:
      tex->_pbuffer->set_format(PixelBuffer::F_rgba4);
      break;
    case EggTexture::F_rgba5:
      tex->_pbuffer->set_format(PixelBuffer::F_rgba5);
      break;

    case EggTexture::F_unspecified:
      break;

    default:
      egg2pg_cat.warning()
        << "Ignoring inappropriate format " << egg_tex->get_format()
        << " for 4-component texture " << egg_tex->get_name() << "\n";
    }
  }
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::apply_texture_apply_attributes
//       Access: Private
//  Description:
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) EggLoader::
get_texture_apply_attributes(const EggTexture *egg_tex) {
  CPT(RenderAttrib) result = TextureApplyAttrib::make(TextureApplyAttrib::M_modulate);
  if (egg_always_decal_textures) {
    result = TextureApplyAttrib::make(TextureApplyAttrib::M_decal);

  } else {
    switch (egg_tex->get_env_type()) {
    case EggTexture::ET_modulate:
      result = TextureApplyAttrib::make(TextureApplyAttrib::M_modulate);
      break;

    case EggTexture::ET_decal:
      result = TextureApplyAttrib::make(TextureApplyAttrib::M_decal);
      break;

    case EggTexture::ET_unspecified:
      break;

    default:
      egg2pg_cat.warning()
        << "Invalid texture environment "
        << (int)egg_tex->get_env_type() << "\n";
    }
  }

  return result;
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::get_material_attrib
//       Access: Private
//  Description: Returns a RenderAttrib suitable for enabling the
//               material indicated by the given EggMaterial, and with
//               the indicated backface flag.
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) EggLoader::
get_material_attrib(const EggMaterial *egg_mat, bool bface) {
  Materials &materials = bface ? _materials_bface : _materials;

  // First, check whether we've seen this material before.
  Materials::const_iterator mi;
  mi = materials.find(egg_mat);
  if (mi != materials.end()) {
    return (*mi).second;
  }

  // Ok, this is the first time we've seen this particular
  // EggMaterial.  Create a new Material that matches it.
  PT(Material) mat = new Material;
  if (egg_mat->has_diff()) {
    mat->set_diffuse(egg_mat->get_diff());
    // By default, ambient is the same as diffuse, if diffuse is
    // specified but ambient is not.
    mat->set_ambient(egg_mat->get_diff());
  }
  if (egg_mat->has_amb()) {
    mat->set_ambient(egg_mat->get_amb());
  }
  if (egg_mat->has_emit()) {
    mat->set_emission(egg_mat->get_emit());
  }
  if (egg_mat->has_spec()) {
    mat->set_specular(egg_mat->get_spec());
  }
  if (egg_mat->has_shininess()) {
    mat->set_shininess(egg_mat->get_shininess());
  }
  if (egg_mat->has_local()) {
    mat->set_local(egg_mat->get_local());
  }

  mat->set_twoside(bface);

  // Now get a global Material pointer, shared with other models.
  const Material *shared_mat = MaterialPool::get_material(mat);

  // And create a MaterialAttrib for this Material.
  CPT(RenderAttrib) mt = MaterialAttrib::make(shared_mat);
  materials.insert(Materials::value_type(egg_mat, mt));

  return mt;
}


////////////////////////////////////////////////////////////////////
//     Function: EggLoader::setup_bucket
//       Access: Private
//  Description:
////////////////////////////////////////////////////////////////////
void EggLoader::
setup_bucket(BuilderBucket &bucket, PandaNode *parent,
             EggPrimitive *egg_prim) {
  bucket._node = parent;
  bucket._mesh = egg_mesh;
  bucket._retesselate_coplanar = egg_retesselate_coplanar;
  bucket._unroll_fans = egg_unroll_fans;
  bucket._show_tstrips = egg_show_tstrips;
  bucket._show_qsheets = egg_show_qsheets;
  bucket._show_quads = egg_show_quads;
  bucket._show_normals = egg_show_normals;
  bucket._normal_scale = egg_normal_scale;
  bucket._subdivide_polys = egg_subdivide_polys;
  bucket._consider_fans = egg_consider_fans;
  bucket._max_tfan_angle = egg_max_tfan_angle;
  bucket._min_tfan_tris = egg_min_tfan_tris;
  bucket._coplanar_threshold = egg_coplanar_threshold;

  // If a primitive has a name that does not begin with a digit, it
  // should be used to group primitives together--i.e. each primitive
  // with the same name gets placed into the same GeomNode.  However,
  // if a prim's name begins with a digit, just ignore it.
  if (egg_prim->has_name() && !isdigit(egg_prim->get_name()[0])) {
    bucket.set_name(egg_prim->get_name());
  }

  // Assign the appropriate properties to the bucket.

  // The various EggRenderMode properties can be defined directly at
  // the primitive, at a group above the primitive, or an a texture
  // applied to the primitive.  The EggNode::determine_*() functions
  // can find the right pointer to the level at which this is actually
  // defined for a given primitive.
  EggRenderMode::AlphaMode am = EggRenderMode::AM_unspecified;
  EggRenderMode::DepthWriteMode dwm = EggRenderMode::DWM_unspecified;
  EggRenderMode::DepthTestMode dtm = EggRenderMode::DTM_unspecified;
  bool implicit_alpha = false;
  bool has_draw_order = false;
  int draw_order = 0;
  bool has_bin = false;
  string bin;

  EggRenderMode *render_mode;
  render_mode = egg_prim->determine_alpha_mode();
  if (render_mode != (EggRenderMode *)NULL) {
    am = render_mode->get_alpha_mode();
  }
  render_mode = egg_prim->determine_depth_write_mode();
  if (render_mode != (EggRenderMode *)NULL) {
    dwm = render_mode->get_depth_write_mode();
  }
  render_mode = egg_prim->determine_depth_test_mode();
  if (render_mode != (EggRenderMode *)NULL) {
    dtm = render_mode->get_depth_test_mode();
  }
  render_mode = egg_prim->determine_draw_order();
  if (render_mode != (EggRenderMode *)NULL) {
    has_draw_order = true;
    draw_order = render_mode->get_draw_order();
  }
  render_mode = egg_prim->determine_bin();
  if (render_mode != (EggRenderMode *)NULL) {
    has_bin = true;
    bin = render_mode->get_bin();
  }

  bucket.add_attrib(TextureAttrib::make_off());
  if (egg_prim->has_texture()) {
    PT(EggTexture) egg_tex = egg_prim->get_texture();

    const TextureDef &def = _textures[egg_tex];
    if (def._texture != (const RenderAttrib *)NULL) {
      bucket.add_attrib(def._texture);
      bucket.add_attrib(def._apply);

      // If neither the primitive nor the texture specified an alpha
      // mode, assume it should be alpha'ed if the texture has an
      // alpha channel.
      if (am == EggRenderMode::AM_unspecified) {
        const TextureAttrib *tex_attrib = DCAST(TextureAttrib, def._texture);
        Texture *tex = tex_attrib->get_texture();
        nassertv(tex != (Texture *)NULL);
        int num_components = tex->_pbuffer->get_num_components();
        if (egg_tex->has_alpha_channel(num_components)) {
          implicit_alpha = true;
        }
      }
    }
  }

  if (egg_prim->has_material()) {
    CPT(RenderAttrib) mt =
      get_material_attrib(egg_prim->get_material(),
                          egg_prim->get_bface_flag());
    bucket.add_attrib(mt);
  }


  // Also check the color of the primitive to see if we should assume
  // alpha based on the alpha values specified in the egg file.
  if (am == EggRenderMode::AM_unspecified) {
    if (egg_prim->has_color()) {
      if (egg_prim->get_color()[3] != 1.0) {
        implicit_alpha = true;
      }
    }
    EggPrimitive::const_iterator vi;
    for (vi = egg_prim->begin();
         !implicit_alpha && vi != egg_prim->end();
         ++vi) {
      if ((*vi)->has_color()) {
        if ((*vi)->get_color()[3] != 1.0) {
          implicit_alpha = true;
        }
      }
    }

    if (implicit_alpha) {
      am = EggRenderMode::AM_on;
    }
  }

  if (am == EggRenderMode::AM_on) {
    // Alpha type "on" means to get the default transparency type.
    am = egg_alpha_mode;
  }

  switch (am) {
  case EggRenderMode::AM_on:
  case EggRenderMode::AM_blend:
    bucket.add_attrib(TransparencyAttrib::make(TransparencyAttrib::M_alpha));
    break;

  case EggRenderMode::AM_blend_no_occlude:
    bucket.add_attrib(TransparencyAttrib::make(TransparencyAttrib::M_alpha));
    bucket.add_attrib(DepthWriteAttrib::make(DepthWriteAttrib::M_off));
    break;

  case EggRenderMode::AM_ms:
    bucket.add_attrib(TransparencyAttrib::make(TransparencyAttrib::M_multisample));
    break;

  case EggRenderMode::AM_ms_mask:
    bucket.add_attrib(TransparencyAttrib::make(TransparencyAttrib::M_multisample_mask));
    break;

  case EggRenderMode::AM_binary:
    bucket.add_attrib(TransparencyAttrib::make(TransparencyAttrib::M_binary));
    break;

  case EggRenderMode::AM_dual:
    bucket.add_attrib(TransparencyAttrib::make(TransparencyAttrib::M_dual));
    break;

  default:
    break;
  }

  switch (dwm) {
  case EggRenderMode::DWM_on:
    bucket.add_attrib(DepthWriteAttrib::make(DepthWriteAttrib::M_on));
    break;

  case EggRenderMode::DWM_off:
    bucket.add_attrib(DepthWriteAttrib::make(DepthWriteAttrib::M_off));
    break;

  default:
    break;
  }

  switch (dtm) {
  case EggRenderMode::DTM_on:
    bucket.add_attrib(DepthTestAttrib::make(DepthTestAttrib::M_less));
    break;

  case EggRenderMode::DTM_off:
    bucket.add_attrib(DepthTestAttrib::make(DepthTestAttrib::M_none));
    break;

  default:
    break;
  }

  if (has_bin) {
    bucket.add_attrib(CullBinAttrib::make(bin, draw_order));

  } else if (has_draw_order) {
    bucket.add_attrib(CullBinAttrib::make("fixed", draw_order));
  }
 

  if (egg_prim->get_bface_flag()) {
    // The primitive is marked with backface culling disabled--we want
    // to see both sides.
    bucket.add_attrib(CullFaceAttrib::make(CullFaceAttrib::M_cull_none));
  }
}



////////////////////////////////////////////////////////////////////
//     Function: EggLoader::make_node
//       Access: Private
//  Description:
////////////////////////////////////////////////////////////////////
PandaNode *EggLoader::
make_node(EggNode *egg_node, PandaNode *parent) {
  if (egg_node->is_of_type(EggNurbsCurve::get_class_type())) {
    return make_node(DCAST(EggNurbsCurve, egg_node), parent);
  } else if (egg_node->is_of_type(EggPrimitive::get_class_type())) {
    return make_node(DCAST(EggPrimitive, egg_node), parent);
  } else if (egg_node->is_of_type(EggBin::get_class_type())) {
    return make_node(DCAST(EggBin, egg_node), parent);
  } else if (egg_node->is_of_type(EggGroup::get_class_type())) {
    return make_node(DCAST(EggGroup, egg_node), parent);
  } else if (egg_node->is_of_type(EggTable::get_class_type())) {
    return make_node(DCAST(EggTable, egg_node), parent);
  } else if (egg_node->is_of_type(EggGroupNode::get_class_type())) {
    return make_node(DCAST(EggGroupNode, egg_node), parent);
  }

  return (PandaNode *)NULL;
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::make_node (EggNurbsCurve)
//       Access: Private
//  Description:
////////////////////////////////////////////////////////////////////
PandaNode *EggLoader::
make_node(EggNurbsCurve *egg_curve, PandaNode *parent) {
  assert(parent != NULL);
  assert(!parent->is_geom_node());

  PT(ParametricCurve) curve;

  if (egg_load_classic_nurbs_curves) {
    curve = new ClassicNurbsCurve;
  } else {
    curve = new NurbsCurve;
  }

  NurbsCurveInterface *nurbs = curve->get_nurbs_interface();
  nassertr(nurbs != (NurbsCurveInterface *)NULL, (PandaNode *)NULL);

  if (egg_curve->get_order() < 1 || egg_curve->get_order() > 4) {
    egg2pg_cat.error()
      << "Invalid NURBSCurve order for " << egg_curve->get_name() << ": "
      << egg_curve->get_order() << "\n";
    _error = true;
    return (PandaNode *)NULL;
  }

  nurbs->set_order(egg_curve->get_order());

  EggPrimitive::const_iterator pi;
  for (pi = egg_curve->begin(); pi != egg_curve->end(); ++pi) {
    nurbs->append_cv(LCAST(float, (*pi)->get_pos4()));
  }

  int num_knots = egg_curve->get_num_knots();
  if (num_knots != nurbs->get_num_knots()) {
    egg2pg_cat.error()
      << "Invalid NURBSCurve number of knots for "
      << egg_curve->get_name() << ": got " << num_knots
      << " knots, expected " << nurbs->get_num_knots() << "\n";
    _error = true;
    return (PandaNode *)NULL;
  }

  for (int i = 0; i < num_knots; i++) {
    nurbs->set_knot(i, egg_curve->get_knot(i));
  }

  switch (egg_curve->get_curve_type()) {
  case EggCurve::CT_xyz:
    curve->set_curve_type(PCT_XYZ);
    break;

  case EggCurve::CT_hpr:
    curve->set_curve_type(PCT_HPR);
    break;

  case EggCurve::CT_t:
    curve->set_curve_type(PCT_T);
    break;

  default:
    break;
  }
  curve->set_name(egg_curve->get_name());

  if (!curve->recompute()) {
    egg2pg_cat.error()
      << "Invalid NURBSCurve " << egg_curve->get_name() << "\n";
    _error = true;
    return (PandaNode *)NULL;
  }

  parent->add_child(curve);
  return curve;
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::make_node (EggPrimitive)
//       Access: Private
//  Description:
////////////////////////////////////////////////////////////////////
PandaNode *EggLoader::
make_node(EggPrimitive *egg_prim, PandaNode *parent) {
  assert(parent != NULL);
  assert(!parent->is_of_type(GeomNode::get_class_type()));

  if (egg_prim->cleanup()) {
    if (parent->is_of_type(SelectiveChildNode::get_class_type())) {
      // If we're putting a primitive under a SelectiveChildNode of
      // some kind, its exact position within the group is relevant,
      // so we need to create a placeholder now.
      PandaNode *group = new PandaNode(egg_prim->get_name());
      parent->add_child(group);
      make_nonindexed_primitive(egg_prim, group);
      return group;
    }

    // Otherwise, we don't really care what the position of this
    // primitive is within its parent's list of children, and in fact
    // we want to allow it to be combined with other polygons added to
    // the same parent.
    make_nonindexed_primitive(egg_prim, parent);
  }
  return (PandaNode *)NULL;
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::make_node (EggBin)
//       Access: Private
//  Description:
////////////////////////////////////////////////////////////////////
PandaNode *EggLoader::
make_node(EggBin *egg_bin, PandaNode *parent) {
  // Presently, an EggBin can only mean an LOD node (i.e. a parent of
  // one or more EggGroups with LOD specifications).  Later it might
  // mean other things as well.

  nassertr((EggBinner::BinNumber)egg_bin->get_bin_number() == EggBinner::BN_lod, NULL);
  LODNode *lod_node = new LODNode(egg_bin->get_name());

  pvector<LODInstance> instances;

  EggGroup::const_iterator ci;
  for (ci = egg_bin->begin(); ci != egg_bin->end(); ++ci) {
    LODInstance instance(*ci);
    instances.push_back(instance);
  }

  // Now that we've created all of our children, put them in the
  // proper order and tell the LOD node about them.
  sort(instances.begin(), instances.end());

  if (!instances.empty()) {
    // Set up the LOD node's center.  All of the children should have
    // the same center, because that's how we binned them.
    lod_node->set_center(LCAST(float, instances[0]._d->_center));
  }

  for (size_t i = 0; i < instances.size(); i++) {
    // Create the children in the proper order within the scene graph.
    const LODInstance &instance = instances[i];
    make_node(instance._egg_node, lod_node);

    // All of the children should have the same center, because that's
    // how we binned them.
    nassertr(lod_node->get_center().almost_equal
             (LCAST(float, instance._d->_center), 0.01), NULL);

    // Tell the LOD node about this child's switching distances.
    lod_node->add_switch(instance._d->_switch_in, instance._d->_switch_out);
  }

  return create_group_arc(egg_bin, parent, lod_node);
}


////////////////////////////////////////////////////////////////////
//     Function: EggLoader::make_node (EggGroup)
//       Access: Private
//  Description:
////////////////////////////////////////////////////////////////////
PandaNode *EggLoader::
make_node(EggGroup *egg_group, PandaNode *parent) {
  PT(PandaNode) node = NULL;

  if (egg_group->get_num_object_types() != 0) {
    pset<string> expanded;
    pvector<string> expanded_history;
    if (!expand_object_types(egg_group, expanded, expanded_history)) {
      return NULL;
    }
  }

  if (egg_group->get_dart_type() != EggGroup::DT_none) {
    // A group with the <Dart> flag set means to create a character.
    CharacterMaker char_maker(egg_group, *this);
    node = char_maker.make_node();

  } else if (egg_group->get_cs_type() != EggGroup::CST_none &&
             egg_group->get_cs_type() != EggGroup::CST_geode) {
    // A collision group: create collision geometry.
    node = new CollisionNode(egg_group->get_name());

    make_collision_solids(egg_group, egg_group, (CollisionNode *)node.p());
    if ((egg_group->get_collide_flags() & EggGroup::CF_keep) != 0) {
      // If we also specified to keep the geometry, continue the
      // traversal.
      EggGroup::const_iterator ci;
      for (ci = egg_group->begin(); ci != egg_group->end(); ++ci) {
        make_node(*ci, parent);
      }
    }

    node = create_group_arc(egg_group, parent, node);

    if (!egg_show_collision_solids) {
      node->set_draw_mask(DrawMask::all_off());
    }
    return node;

  } else if (egg_group->get_switch_flag()) {
    if (egg_group->get_switch_fps() != 0.0) {
      // Create a sequence node.
      node = new SequenceNode(egg_group->get_switch_fps(), 
                              egg_group->get_name());
    } else {
      // Create a switch node.
      node = new SwitchNode(egg_group->get_name());
    }
      
    EggGroup::const_iterator ci;
    for (ci = egg_group->begin(); ci != egg_group->end(); ++ci) {
      make_node(*ci, node);
    }

  } else if (egg_group->get_model_flag() || 
             egg_group->get_dcs_type() != EggGroup::DC_none) {
    // A model or DCS flag; create a model node.
    node = new ModelNode(egg_group->get_name());
    switch (egg_group->get_dcs_type()) {
    case EggGroup::DC_net:
      DCAST(ModelNode, node)->set_preserve_transform(ModelNode::PT_net);
      break;

    case EggGroup::DC_local:
    case EggGroup::DC_default:
      DCAST(ModelNode, node)->set_preserve_transform(ModelNode::PT_local);
      break;

    case EggGroup::DC_none:
      break;
    }

    EggGroup::const_iterator ci;
    for (ci = egg_group->begin(); ci != egg_group->end(); ++ci) {
      make_node(*ci, node);
    }

  } else {
    // A normal group; just create a normal node, and traverse.
    node = new PandaNode(egg_group->get_name());

    EggGroup::const_iterator ci;
    for (ci = egg_group->begin(); ci != egg_group->end(); ++ci) {
      make_node(*ci, node);
    }
  }

  if (node == (PandaNode *)NULL) {
    return NULL;
  }
  return create_group_arc(egg_group, parent, node);
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::create_group_arc
//       Access: Private
//  Description: Creates the arc parenting a new group to the scene
//               graph, and applies any relevant attribs to the
//               arc according to the EggGroup node that inspired the
//               group.
////////////////////////////////////////////////////////////////////
PandaNode *EggLoader::
create_group_arc(EggGroup *egg_group, PandaNode *parent, PandaNode *node) {
  parent->add_child(node);

  // If the group had a transform, apply it to the arc.
  if (egg_group->has_transform()) {
    node->set_transform(make_transform(egg_group));
  }

  // If the group has a billboard flag, apply that.
  switch (egg_group->get_billboard_type()) {
  case EggGroup::BT_point_camera_relative:
    node->set_effect(BillboardEffect::make_point_eye());
    break;

  case EggGroup::BT_point_world_relative:
    node->set_effect(BillboardEffect::make_point_world());
    break;

  case EggGroup::BT_axis:
    node->set_effect(BillboardEffect::make_axis());
    break;

  case EggGroup::BT_none:
    break;
  }

  if (egg_group->get_decal_flag()) {
    if (egg_ignore_decals) {
      egg2pg_cat.error()
        << "Ignoring decal flag on " << egg_group->get_name() << "\n";
      _error = true;
    }

    // If the group has the "decal" flag set, it means that all of the
    // descendant groups will be decaled onto the geometry within
    // this group.  This means we'll need to reparent things a bit
    // afterward.
    _decals.insert(node);
  }

  // If the group specified some property that should propagate down
  // to the leaves, we have to remember this node and apply the
  // property later, after we've created the actual geometry.
  DeferredNodeProperty def;
  if (egg_group->has_collide_mask()) {
    def._from_collide_mask = egg_group->get_collide_mask();
    def._into_collide_mask = egg_group->get_collide_mask();
    def._flags |=
      DeferredNodeProperty::F_has_from_collide_mask |
      DeferredNodeProperty::F_has_into_collide_mask;
  }
  if (egg_group->has_from_collide_mask()) {
    def._from_collide_mask = egg_group->get_from_collide_mask();
    def._flags |= DeferredNodeProperty::F_has_from_collide_mask;
  }
  if (egg_group->has_into_collide_mask()) {
    def._into_collide_mask = egg_group->get_into_collide_mask();
    def._flags |= DeferredNodeProperty::F_has_into_collide_mask;
  }

  if (def._flags != 0) {
    _deferred_nodes[node] = def;
  }

  return node;
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::make_node (EggTable)
//       Access: Private
//  Description:
////////////////////////////////////////////////////////////////////
PandaNode *EggLoader::
make_node(EggTable *egg_table, PandaNode *parent) {
  if (egg_table->get_table_type() != EggTable::TT_bundle) {
    // We only do anything with bundles.  Isolated tables are treated
    // as ordinary groups.
    return make_node(DCAST(EggGroupNode, egg_table), parent);
  }

  // It's an actual bundle, so make an AnimBundle from it and its
  // descendants.
  AnimBundleMaker bundle_maker(egg_table);
  AnimBundleNode *node = bundle_maker.make_node();
  parent->add_child(node);
  return node;
}


////////////////////////////////////////////////////////////////////
//     Function: EggLoader::make_node (EggGroupNode)
//       Access: Private
//  Description:
////////////////////////////////////////////////////////////////////
PandaNode *EggLoader::
make_node(EggGroupNode *egg_group, PandaNode *parent) {
  PandaNode *node = new PandaNode(egg_group->get_name());

  EggGroupNode::const_iterator ci;
  for (ci = egg_group->begin(); ci != egg_group->end(); ++ci) {
    make_node(*ci, node);
  }

  parent->add_child(node);
  return node;
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::make_collision_solids
//       Access: Private
//  Description: Creates CollisionSolids corresponding to the
//               collision geometry indicated at the given node and
//               below.
////////////////////////////////////////////////////////////////////
void EggLoader::
make_collision_solids(EggGroup *start_group, EggGroup *egg_group,
                      CollisionNode *cnode) {
  if (egg_group->get_cs_type() != EggGroup::CST_none) {
    start_group = egg_group;
  }

  switch (start_group->get_cs_type()) {
  case EggGroup::CST_none:
  case EggGroup::CST_geode:
    // No collision flags; do nothing.  Don't even traverse further.
    return;

  case EggGroup::CST_inverse_sphere:
    // These aren't presently supported.
    egg2pg_cat.error()
      << "Not presently supported: <Collide> { "
      << egg_group->get_cs_type() << " }\n";
    _error = true;
    break;

  case EggGroup::CST_plane:
    make_collision_plane(egg_group, cnode, start_group->get_collide_flags());
    break;

  case EggGroup::CST_polygon:
    make_collision_polygon(egg_group, cnode, start_group->get_collide_flags());
    break;

  case EggGroup::CST_polyset:
    make_collision_polyset(egg_group, cnode, start_group->get_collide_flags());
    break;

  case EggGroup::CST_sphere:
    make_collision_sphere(egg_group, cnode, start_group->get_collide_flags());
    break;
  }

  if ((start_group->get_collide_flags() & EggGroup::CF_descend) != 0) {
    // Now pick up everything below.
    EggGroup::const_iterator ci;
    for (ci = egg_group->begin(); ci != egg_group->end(); ++ci) {
      if ((*ci)->is_of_type(EggGroup::get_class_type())) {
        make_collision_solids(start_group, DCAST(EggGroup, *ci), cnode);
      }
    }
  }
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::make_collision_plane
//       Access: Private
//  Description: Creates a single CollisionPlane corresponding
//               to the first polygon associated with this group.
////////////////////////////////////////////////////////////////////
void EggLoader::
make_collision_plane(EggGroup *egg_group, CollisionNode *cnode,
                     EggGroup::CollideFlags flags) {
  EggGroup *geom_group = find_collision_geometry(egg_group);
  if (geom_group != (EggGroup *)NULL) {
    EggGroup::const_iterator ci;
    for (ci = geom_group->begin(); ci != geom_group->end(); ++ci) {
      if ((*ci)->is_of_type(EggPolygon::get_class_type())) {
        CollisionPlane *csplane =
          create_collision_plane(DCAST(EggPolygon, *ci), egg_group);
        if (csplane != (CollisionPlane *)NULL) {
          apply_collision_flags(csplane, flags);
          cnode->add_solid(csplane);
          return;
        }
      }
    }
  }
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::make_collision_polygon
//       Access: Private
//  Description: Creates a single CollisionPolygon corresponding
//               to the first polygon associated with this group.
////////////////////////////////////////////////////////////////////
void EggLoader::
make_collision_polygon(EggGroup *egg_group, CollisionNode *cnode,
                       EggGroup::CollideFlags flags) {

  EggGroup *geom_group = find_collision_geometry(egg_group);
  if (geom_group != (EggGroup *)NULL) {
    EggGroup::const_iterator ci;
    for (ci = geom_group->begin(); ci != geom_group->end(); ++ci) {
      if ((*ci)->is_of_type(EggPolygon::get_class_type())) {
        create_collision_polygons(cnode, DCAST(EggPolygon, *ci),
                                  egg_group, flags);
      }
    }
  }
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::make_collision_polyset
//       Access: Private
//  Description: Creates a series of CollisionPolygons corresponding
//               to the polygons associated with this group.
////////////////////////////////////////////////////////////////////
void EggLoader::
make_collision_polyset(EggGroup *egg_group, CollisionNode *cnode,
                       EggGroup::CollideFlags flags) {
  EggGroup *geom_group = find_collision_geometry(egg_group);
  if (geom_group != (EggGroup *)NULL) {
    EggGroup::const_iterator ci;
    for (ci = geom_group->begin(); ci != geom_group->end(); ++ci) {
      if ((*ci)->is_of_type(EggPolygon::get_class_type())) {
        create_collision_polygons(cnode, DCAST(EggPolygon, *ci),
                                  egg_group, flags);
      }
    }
  }
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::make_collision_sphere
//       Access: Private
//  Description: Creates a single CollisionSphere corresponding
//               to the polygons associated with this group.
////////////////////////////////////////////////////////////////////
void EggLoader::
make_collision_sphere(EggGroup *egg_group, CollisionNode *cnode,
                      EggGroup::CollideFlags flags) {
  EggGroup *geom_group = find_collision_geometry(egg_group);
  if (geom_group != (EggGroup *)NULL) {
    // Collect all of the vertices.
    pset<EggVertex *> vertices;

    EggGroup::const_iterator ci;
    for (ci = geom_group->begin(); ci != geom_group->end(); ++ci) {
      if ((*ci)->is_of_type(EggPrimitive::get_class_type())) {
        EggPrimitive *prim = DCAST(EggPrimitive, *ci);
        EggPrimitive::const_iterator pi;
        for (pi = prim->begin(); pi != prim->end(); ++pi) {
          vertices.insert(*pi);
        }
      }
    }

    // Now average together all of the vertices to get a center.
    int num_vertices = 0;
    LPoint3d center(0.0, 0.0, 0.0);
    pset<EggVertex *>::const_iterator vi;

    for (vi = vertices.begin(); vi != vertices.end(); ++vi) {
      EggVertex *vtx = (*vi);
      if (vtx->get_num_dimensions() == 3) {
        center += vtx->get_pos3();
        num_vertices++;

      } else if (vtx->get_num_dimensions() == 4) {
        LPoint4d p4 = vtx->get_pos4();
        if (p4[3] != 0.0) {
          center += LPoint3d(p4[0], p4[1], p4[2]) / p4[3];
          num_vertices++;
        }
      }
    }

    if (num_vertices > 0) {
      center /= (double)num_vertices;

      LMatrix4d mat = egg_group->get_vertex_to_node();
      center = center * mat;

      // And the furthest vertex determines the radius.
      double radius2 = 0.0;
      for (vi = vertices.begin(); vi != vertices.end(); ++vi) {
        EggVertex *vtx = (*vi);
        if (vtx->get_num_dimensions() == 3) {
          LPoint3d p3 = vtx->get_pos3();
          LVector3d v = p3 * mat - center;
          radius2 = max(radius2, v.length_squared());

        } else if (vtx->get_num_dimensions() == 4) {
          LPoint4d p4 = vtx->get_pos4();
          if (p4[3] != 0.0) {
            LPoint3d p3 = LPoint3d(p4[0], p4[1], p4[2]) / p4[3];
            LVector3d v = p3 * mat - center;
            radius2 = max(radius2, v.length_squared());
          }
        }
      }

      float radius = sqrtf(radius2);
      CollisionSphere *cssphere =
        new CollisionSphere(LCAST(float, center), radius);
      apply_collision_flags(cssphere, flags);
      cnode->add_solid(cssphere);
    }
  }
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::apply_collision_flags
//       Access: Private
//  Description: Does funny stuff to the CollisionSolid as
//               appropriate, based on the settings of the given
//               CollideFlags.
////////////////////////////////////////////////////////////////////
void EggLoader::
apply_collision_flags(CollisionSolid *solid,
                      EggGroup::CollideFlags flags) {
  if ((flags & EggGroup::CF_intangible) != 0) {
    solid->set_tangible(false);
  }
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::find_collision_geometry
//       Access: Private
//  Description: Looks for the node, at or below the indicated node,
//               that contains the associated collision geometry.
////////////////////////////////////////////////////////////////////
EggGroup *EggLoader::
find_collision_geometry(EggGroup *egg_group) {
  if ((egg_group->get_collide_flags() & EggGroup::CF_descend) != 0) {
    // If we have the "descend" instruction, we'll get to it when we
    // get to it.  Don't worry about it now.
    return egg_group;
  }

  // Does this group have any polygons?
  EggGroup::const_iterator ci;
  for (ci = egg_group->begin(); ci != egg_group->end(); ++ci) {
    if ((*ci)->is_of_type(EggPolygon::get_class_type())) {
      // Yes!  Use this group.
      return egg_group;
    }
  }

  // Well, the group had no polygons; look for a child group that has
  // the same collision type.
  for (ci = egg_group->begin(); ci != egg_group->end(); ++ci) {
    if ((*ci)->is_of_type(EggGroup::get_class_type())) {
      EggGroup *child_group = DCAST(EggGroup, *ci);
      if (child_group->get_cs_type() == egg_group->get_cs_type()) {
        return child_group;
      }
    }
  }

  // We got nothing.
  return NULL;
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::create_collision_plane
//       Access: Private
//  Description: Creates a single CollisionPlane from the indicated
//               EggPolygon.
////////////////////////////////////////////////////////////////////
CollisionPlane *EggLoader::
create_collision_plane(EggPolygon *egg_poly, EggGroup *parent_group) {
  if (!egg_poly->cleanup()) {
    egg2pg_cat.error()
      << "Degenerate collision plane in " << parent_group->get_name()
      << "\n";
    _error = true;
    return NULL;
  }

  LMatrix4d mat = egg_poly->get_vertex_to_node();

  pvector<Vertexf> vertices;
  if (!egg_poly->empty()) {
    EggPolygon::const_iterator vi;
    vi = egg_poly->begin();

    Vertexd vert = (*vi)->get_pos3() * mat;
    vertices.push_back(LCAST(float, vert));

    Vertexd last_vert = vert;
    ++vi;
    while (vi != egg_poly->end()) {
      vert = (*vi)->get_pos3() * mat;
      if (!vert.almost_equal(last_vert)) {
        vertices.push_back(LCAST(float, vert));
      }

      last_vert = vert;
      ++vi;
    }
  }

  if (vertices.size() < 3) {
    return NULL;
  }
  Planef plane(vertices[0], vertices[1], vertices[2]);
  return new CollisionPlane(plane);
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::create_collision_polygons
//       Access: Private
//  Description: Creates one or more CollisionPolygons from the
//               indicated EggPolygon, and adds them to the indicated
//               CollisionNode.
////////////////////////////////////////////////////////////////////
void EggLoader::
create_collision_polygons(CollisionNode *cnode, EggPolygon *egg_poly,
                          EggGroup *parent_group,
                          EggGroup::CollideFlags flags) {
  LMatrix4d mat = egg_poly->get_vertex_to_node();

  PT(EggGroup) group = new EggGroup;

  if (!egg_poly->triangulate_into(group, false)) {
    egg2pg_cat.error()
      << "Degenerate collision polygon in " << parent_group->get_name()
      << "\n";
    _error = true;
    return;
  }

  if (group->size() != 1) {
    egg2pg_cat.error()
      << "Concave collision polygon in " << parent_group->get_name()
      << "\n";
    _error = true;
  }

  EggGroup::iterator ci;
  for (ci = group->begin(); ci != group->end(); ++ci) {
    EggPolygon *poly = DCAST(EggPolygon, *ci);

    pvector<Vertexf> vertices;
    if (!poly->empty()) {
      EggPolygon::const_iterator vi;
      vi = poly->begin();

      Vertexd vert = (*vi)->get_pos3() * mat;
      vertices.push_back(LCAST(float, vert));

      Vertexd last_vert = vert;
      ++vi;
      while (vi != poly->end()) {
        vert = (*vi)->get_pos3() * mat;
        if (!vert.almost_equal(last_vert)) {
          vertices.push_back(LCAST(float, vert));
        }

        last_vert = vert;
        ++vi;
      }
    }

    if (vertices.size() >= 3) {
      const Vertexf *vertices_begin = &vertices[0];
      const Vertexf *vertices_end = vertices_begin + vertices.size();
      CollisionPolygon *cspoly =
        new CollisionPolygon(vertices_begin, vertices_end);
      apply_collision_flags(cspoly, flags);
      cnode->add_solid(cspoly);
    }
  }
}


////////////////////////////////////////////////////////////////////
//     Function: EggLoader::apply_deferred_nodes
//       Access: Private
//  Description: Walks back over the tree and applies the
//               DeferredNodeProperties that were saved up along the
//               way.
////////////////////////////////////////////////////////////////////
void EggLoader::
apply_deferred_nodes(PandaNode *node, const DeferredNodeProperty &prop) {
  DeferredNodeProperty next_prop(prop);

  // Do we have a DeferredNodeProperty associated with this node?
  DeferredNodes::const_iterator dni;
  dni = _deferred_nodes.find(node);

  if (dni != _deferred_nodes.end()) {
    const DeferredNodeProperty &def = (*dni).second;
    next_prop.compose(def);
  }

  // Now apply the accumulated state to the node.
  next_prop.apply_to_node(node);

  int num_children = node->get_num_children();
  for (int i = 0; i < num_children; i++) {
    apply_deferred_nodes(node->get_child(i), next_prop);
  }
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::expand_object_types
//       Access: Private
//  Description: Recursively expands the group's ObjectType string(s).
//               It's recursive because an ObjectType string might
//               itself expand to another ObjectType string, which is
//               allowed; but we don't want to get caught in a cycle.
//
//               The return value is true if the object type is
//               expanded and the node is valid, or false if the node
//               should be ignored (e.g. ObjectType "backstage").
////////////////////////////////////////////////////////////////////
bool EggLoader::
expand_object_types(EggGroup *egg_group, const pset<string> &expanded,
                    const pvector<string> &expanded_history) {
  int num_object_types = egg_group->get_num_object_types();

  // First, copy out the object types so we can recursively modify the
  // list.
  vector_string object_types;
  int i;
  for (i = 0; i < num_object_types; i++) {
    object_types.push_back(egg_group->get_object_type(i));
  }
  egg_group->clear_object_types();

  for (i = 0; i < num_object_types; i++) {
    string object_type = object_types[i];
    pset<string> new_expanded(expanded);

    // Check for a cycle.
    if (!new_expanded.insert(object_type).second) {
      egg2pg_cat.error()
        << "Cycle in ObjectType expansions:\n";
      pvector<string>::const_iterator pi;
      for (pi = expanded_history.begin();
           pi != expanded_history.end();
           ++pi) {
        egg2pg_cat.error(false) 
          << (*pi) << " -> ";
      }
      egg2pg_cat.error(false) << object_type << "\n";
      _error = true;

    } else {
      // No cycle; continue.
      pvector<string> new_expanded_history(expanded_history);
      new_expanded_history.push_back(object_type);

      if (!do_expand_object_type(egg_group, new_expanded, 
                                 new_expanded_history, object_type)) {
        // Ignorable group; stop here.
        return false;
      }
    }
  }

  return true;
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::expand_object_type
//       Access: Private
//  Description: Further implementation of expand_object_types().
////////////////////////////////////////////////////////////////////
bool EggLoader::
do_expand_object_type(EggGroup *egg_group, const pset<string> &expanded,
                      const pvector<string> &expanded_history,
                      const string &object_type) {
  // Try to find the egg syntax that the given objecttype is
  // shorthand for.  First, look in the config file.

  string egg_syntax =
    config_egg2pg.GetString("egg-object-type-" + downcase(object_type), "none");

  if (egg_syntax == "none") {
    // It wasn't defined in a config file.  Maybe it's built in?
    
    if (cmp_nocase_uh(object_type, "barrier") == 0) {
      egg_syntax = "<Collide> { Polyset descend }";
      
    } else if (cmp_nocase_uh(object_type, "solidpoly") == 0) {
      egg_syntax = "<Collide> { Polyset descend solid }";
      
    } else if (cmp_nocase_uh(object_type, "turnstile") == 0) {
      egg_syntax = "<Collide> { Polyset descend turnstile }";
      
    } else if (cmp_nocase_uh(object_type, "sphere") == 0) {
      egg_syntax = "<Collide> { Sphere descend }";
      
    } else if (cmp_nocase_uh(object_type, "trigger") == 0) {
      egg_syntax = "<Collide> { Polyset descend intangible }";
      
    } else if (cmp_nocase_uh(object_type, "trigger_sphere") == 0) {
      egg_syntax = "<Collide> { Sphere descend intangible }";
      
    } else if (cmp_nocase_uh(object_type, "eye_trigger") == 0) {
      egg_syntax = "<Collide> { Polyset descend intangible center }";
      
    } else if (cmp_nocase_uh(object_type, "bubble") == 0) {
      egg_syntax = "<Collide> { Sphere keep descend }";
      
    } else if (cmp_nocase_uh(object_type, "ghost") == 0) {
      egg_syntax = "<Scalar> collide-mask { 0 }";
      
    } else if (cmp_nocase_uh(object_type, "dcs") == 0) {
      egg_syntax = "<DCS> { 1 }";
      
    } else if (cmp_nocase_uh(object_type, "model") == 0) {
      egg_syntax = "<Model> { 1 }";
      
    } else if (cmp_nocase_uh(object_type, "backstage") == 0) {
      // Ignore "backstage" geometry.
      return false;
      
    } else {
      egg2pg_cat.error()
        << "Unknown ObjectType " << object_type << "\n";
      _error = true;
      return true;
    }
  }

  if (!egg_syntax.empty()) {
    if (!egg_group->parse_egg(egg_syntax)) {
      egg2pg_cat.error()
        << "Error while parsing definition for ObjectType "
        << object_type << "\n";
      _error = true;

    } else {
      // Now we've parsed the object type syntax, which might have
      // added more object types.  Recurse if necessary.
      if (egg_group->get_num_object_types() != 0) {
        if (!expand_object_types(egg_group, expanded, expanded_history)) {
          return false;
        }
      }
    }
  }

  return true;
}

////////////////////////////////////////////////////////////////////
//     Function: EggLoader::make_transform
//       Access: Private
//  Description: Walks back over the tree and applies the
//               DeferredNodeProperties that were saved up along the
//               way.
////////////////////////////////////////////////////////////////////
CPT(TransformState) EggLoader::
make_transform(const EggTransform3d *egg_transform) {
  // We'll build up the transform componentwise, so we preserve any
  // componentwise properties of the egg transform.

  CPT(TransformState) ts = TransformState::make_identity();
  int num_components = egg_transform->get_num_components();
  for (int i = 0; i < num_components; i++) {
    switch (egg_transform->get_component_type(i)) {
    case EggTransform3d::CT_translate:
      {
        LVector3f trans(LCAST(float, egg_transform->get_component_vector(i)));
        ts = TransformState::make_pos(trans)->compose(ts);
      }
      break;

    case EggTransform3d::CT_rotx:
      {
        LRotationf rot(LVector3f(1.0f, 0.0f, 0.0f),
                       (float)egg_transform->get_component_number(i));
        ts = TransformState::make_quat(rot)->compose(ts);
      }
      break;

    case EggTransform3d::CT_roty:
      {
        LRotationf rot(LVector3f(0.0f, 1.0f, 0.0f),
                       (float)egg_transform->get_component_number(i));
        ts = TransformState::make_quat(rot)->compose(ts);
      }
      break;

    case EggTransform3d::CT_rotz:
      {
        LRotationf rot(LVector3f(0.0f, 0.0f, 1.0f),
                       (float)egg_transform->get_component_number(i));
        ts = TransformState::make_quat(rot)->compose(ts);
      }
      break;

    case EggTransform3d::CT_rotate:
      {
        LRotationf rot(LCAST(float, egg_transform->get_component_vector(i)),
                       (float)egg_transform->get_component_number(i));
        ts = TransformState::make_quat(rot)->compose(ts);
      }
      break;

    case EggTransform3d::CT_scale:
      {
        LVecBase3f scale(LCAST(float, egg_transform->get_component_vector(i)));
        ts = TransformState::make_scale(scale)->compose(ts);
      }
      break;

    case EggTransform3d::CT_uniform_scale:
      {
        float scale = (float)egg_transform->get_component_number(i);
        ts = TransformState::make_scale(scale)->compose(ts);
      }
      break;

    case EggTransform3d::CT_matrix:
      {
        LMatrix4f mat(LCAST(float, egg_transform->get_component_matrix(i)));
        ts = TransformState::make_mat(mat)->compose(ts);
      }
      break;

    case EggTransform3d::CT_invalid:
      nassertr(false, ts);
      break;
    }
  }

  return ts;
}

---