panda3d/panda/src/gobj/texturePool.cxx

/**
 * PANDA 3D SOFTWARE
 * Copyright (c) Carnegie Mellon University.  All rights reserved.
 *
 * All use of this software is subject to the terms of the revised BSD
 * license.  You should have received a copy of this license along
 * with this source code in a file named "LICENSE."
 *
 * @file texturePool.cxx
 * @author drose
 * @date 2000-04-26
 * @author fperazzi, PandaSE
 * @date 2010-04-29
 */

#include "texturePool.h"
#include "config_gobj.h"
#include "config_util.h"
#include "config_express.h"
#include "string_utils.h"
#include "virtualFileSystem.h"
#include "bamCache.h"
#include "bamCacheRecord.h"
#include "pnmFileTypeRegistry.h"
#include "texturePoolFilter.h"
#include "configVariableList.h"
#include "load_dso.h"
#include "mutexHolder.h"
#include "dcast.h"

TexturePool *TexturePool::_global_ptr;

/**
 * Lists the contents of the texture pool to the indicated output stream.  For
 * debugging.
 */
void TexturePool::
write(ostream &out) {
  get_global_ptr()->ns_list_contents(out);
}

/**
 * Records a factory function that makes a Texture object of the appropriate
 * type for one or more particular filename extensions.  The string extensions
 * may be a string that contains space-separated list of extensions, case-
 * insensitive.
 */
void TexturePool::
register_texture_type(MakeTextureFunc *func, const string &extensions) {
  MutexHolder holder(_lock);

  vector_string words;
  extract_words(downcase(extensions), words);

  vector_string::const_iterator wi;
  for (wi = words.begin(); wi != words.end(); ++wi) {
    _type_registry[*wi] = func;
  }
}

/**
 * Records a TexturePoolFilter object that may operate on texture images as
 * they are loaded from disk.
 */
void TexturePool::
register_filter(TexturePoolFilter *filter) {
  MutexHolder holder(_lock);

  gobj_cat.info()
    << "Registering Texture filter " << *filter << "\n";
  _filter_registry.push_back(filter);
}

/**
 * Returns the factory function to construct a new texture of the type
 * appropriate for the indicated filename extension, if any, or NULL if the
 * extension is not one of the extensions for a texture file.
 */
TexturePool::MakeTextureFunc *TexturePool::
get_texture_type(const string &extension) const {
  MutexHolder holder(_lock);

  string c = downcase(extension);
  TypeRegistry::const_iterator ti;
  ti = _type_registry.find(c);
  if (ti != _type_registry.end()) {
    return (*ti).second;
  }

  // Check the PNM type registry.
  PNMFileTypeRegistry *pnm_reg = PNMFileTypeRegistry::get_global_ptr();
  PNMFileType *type = pnm_reg->get_type_from_extension(c);
  if (type != (PNMFileType *)NULL || c == "txo" || c == "dds" || c == "ktx") {
    // This is a known image type; create an ordinary Texture.
    ((TexturePool *)this)->_type_registry[c] = Texture::make_texture;
    return Texture::make_texture;
  }

  // This is an unknown texture type.
  return NULL;
}

/**
 * Outputs a list of the available texture types to the indicated output
 * stream.  This is mostly the list of available image types, with maybe a few
 * additional ones for video textures.
 */
void TexturePool::
write_texture_types(ostream &out, int indent_level) const {
  MutexHolder holder(_lock);

  // These are supported out of the box.
  indent(out, indent_level) << "Texture Object                  .txo\n";
  indent(out, indent_level) << "DirectDraw Surface              .dds\n";
  indent(out, indent_level) << "Khronos Texture                 .ktx\n";

  PNMFileTypeRegistry *pnm_reg = PNMFileTypeRegistry::get_global_ptr();
  pnm_reg->write(out, indent_level);

  // Also output any of the additional texture types, that aren't strictly
  // images (these are typically video textures).
  TypeRegistry::const_iterator ti;
  for (ti = _type_registry.begin(); ti != _type_registry.end(); ++ti) {
    string extension = (*ti).first;
    MakeTextureFunc *func = (*ti).second;

    if (pnm_reg->get_type_from_extension(extension) == NULL) {
      PT(Texture) tex = func();
      string name = tex->get_type().get_name();
      indent(out, indent_level) << name;
      indent(out, max(30 - (int)name.length(), 0))
        << "  ." << extension << "\n";
    }
  }
}

/**
 * Initializes and/or returns the global pointer to the one TexturePool object
 * in the system.
 */
TexturePool *TexturePool::
get_global_ptr() {
  if (_global_ptr == (TexturePool *)NULL) {
    _global_ptr = new TexturePool;

    // We have to call this here, not in the constructor, so that the
    // _global_ptr is safely assigned by the time the filters begin to load.
    _global_ptr->load_filters();
  }
  return _global_ptr;
}

/**
 * The constructor is not intended to be called directly; there's only
 * supposed to be one TexturePool in the universe and it constructs itself.
 */
TexturePool::
TexturePool() {
  ConfigVariableFilename fake_texture_image
    ("fake-texture-image", "",
     PRC_DESC("Set this to enable a speedy-load mode in which you don't care "
              "what the world looks like, you just want it to load in minimal "
              "time.  This causes all texture loads via the TexturePool to use "
              "the same texture file, which will presumably only be loaded "
              "once."));
  _fake_texture_image = fake_texture_image;
}

/**
 * The nonstatic implementation of has_texture().
 */
bool TexturePool::
ns_has_texture(const Filename &orig_filename) {
  MutexHolder holder(_lock);

  Filename filename;
  resolve_filename(filename, orig_filename, false, LoaderOptions());

  Textures::const_iterator ti;
  ti = _textures.find(filename);
  if (ti != _textures.end()) {
    // This texture was previously loaded.
    return true;
  }

  return false;
}

/**
 * The nonstatic implementation of load_texture().
 */
Texture *TexturePool::
ns_load_texture(const Filename &orig_filename, int primary_file_num_channels,
                bool read_mipmaps, const LoaderOptions &options) {
  Filename filename;

  {
    MutexHolder holder(_lock);
    resolve_filename(filename, orig_filename, read_mipmaps, options);
    Textures::const_iterator ti;
    ti = _textures.find(filename);
    if (ti != _textures.end()) {
      // This texture was previously loaded.
      Texture *tex = (*ti).second;
      nassertr(!tex->get_fullpath().empty(), tex);
      return tex;
    }
  }

  // The texture was not found in the pool.
  PT(Texture) tex;
  PT(BamCacheRecord) record;
  bool store_record = false;

  // Can one of our texture filters supply the texture?
  tex = pre_load(orig_filename, Filename(), primary_file_num_channels, 0,
                 read_mipmaps, options);

  BamCache *cache = BamCache::get_global_ptr();
  bool compressed_cache_record = false;
  try_load_cache(tex, cache, filename, record, compressed_cache_record,
                 options);

  if (tex == (Texture *)NULL) {
    // The texture was neither in the pool, nor found in the on-disk cache; it
    // needs to be loaded from its source image(s).
    gobj_cat.info()
      << "Loading texture " << filename << "\n";

    string ext = downcase(filename.get_extension());
    if (ext == "txo" || ext == "bam") {
      // Assume this is a txo file, which might conceivably contain a movie
      // file or some other subclass of Texture.  In that case, use
      // make_from_txo() to load it instead of read().
      VirtualFileSystem *vfs = VirtualFileSystem::get_global_ptr();

      filename.set_binary();
      PT(VirtualFile) file = vfs->get_file(filename);
      if (file == (VirtualFile *)NULL) {
        // No such file.
        gobj_cat.error()
          << "Could not find " << filename << "\n";
        return NULL;
      }

      if (gobj_cat.is_debug()) {
        gobj_cat.debug()
          << "Reading texture object " << filename << "\n";
      }

      istream *in = file->open_read_file(true);
      tex = Texture::make_from_txo(*in, filename);
      vfs->close_read_file(in);

      if (tex == (Texture *)NULL) {
        return NULL;
      }
      tex->set_fullpath(filename);
      tex->clear_alpha_fullpath();
      tex->set_keep_ram_image(false);

    } else {
      // Read it the conventional way.
      tex = ns_make_texture(ext);
      if (!tex->read(filename, Filename(), primary_file_num_channels, 0,
                     0, 0, false, read_mipmaps, record, options)) {
        // This texture was not found or could not be read.
        report_texture_unreadable(filename);
        return NULL;
      }
    }

    if (options.get_texture_flags() & LoaderOptions::TF_preload_simple) {
      tex->generate_simple_ram_image();
    }

    store_record = (record != (BamCacheRecord *)NULL);
  }

  if (cache->get_cache_compressed_textures() && tex->has_compression()) {
#ifndef HAVE_SQUISH
    bool needs_driver_compression = true;
#else
    bool needs_driver_compression = driver_compress_textures;
#endif // HAVE_SQUISH
    if (needs_driver_compression) {
      // We don't want to save the uncompressed version; we'll save the
      // compressed version when it becomes available.
      store_record = false;
      if (!compressed_cache_record) {
        tex->set_post_load_store_cache(true);
      }
    }

  } else if (!cache->get_cache_textures()) {
    // We don't want to save this texture.
    store_record = false;
  }

  // Set the original filename, before we searched along the path.
  nassertr(tex != (Texture *)NULL, NULL);
  tex->set_filename(orig_filename);
  tex->set_fullpath(filename);
  tex->_texture_pool_key = filename;

  {
    MutexHolder holder(_lock);

    // Now look again--someone may have just loaded this texture in another
    // thread.
    Textures::const_iterator ti;
    ti = _textures.find(filename);
    if (ti != _textures.end()) {
      // This texture was previously loaded.
      Texture *tex = (*ti).second;
      nassertr(!tex->get_fullpath().empty(), tex);
      return tex;
    }

    _textures[filename] = tex;
  }

  if (store_record && tex->is_cacheable()) {
    // Store the on-disk cache record for next time.
    record->set_data(tex);
    cache->store(record);
  }

  if (!(options.get_texture_flags() & LoaderOptions::TF_preload)) {
    // And now drop the RAM until we need it.
    tex->clear_ram_image();
  }

  nassertr(!tex->get_fullpath().empty(), tex);

  // Finally, apply any post-loading texture filters.
  tex = post_load(tex);

  return tex;
}

/**
 * The nonstatic implementation of load_texture().
 */
Texture *TexturePool::
ns_load_texture(const Filename &orig_filename,
                const Filename &orig_alpha_filename,
                int primary_file_num_channels,
                int alpha_file_channel,
                bool read_mipmaps, const LoaderOptions &options) {
  if (!_fake_texture_image.empty()) {
    return ns_load_texture(_fake_texture_image, primary_file_num_channels,
                           read_mipmaps, options);
  }

  Filename filename;
  Filename alpha_filename;

  {
    MutexHolder holder(_lock);
    resolve_filename(filename, orig_filename, read_mipmaps, options);
    resolve_filename(alpha_filename, orig_alpha_filename, read_mipmaps, options);

    Textures::const_iterator ti;
    ti = _textures.find(filename);
    if (ti != _textures.end()) {
      // This texture was previously loaded.
      Texture *tex = (*ti).second;
      nassertr(!tex->get_fullpath().empty(), tex);
      return tex;
    }
  }

  PT(Texture) tex;
  PT(BamCacheRecord) record;
  bool store_record = false;

  // Can one of our texture filters supply the texture?
  tex = pre_load(orig_filename, alpha_filename, primary_file_num_channels,
                 alpha_file_channel, read_mipmaps, options);

  BamCache *cache = BamCache::get_global_ptr();
  bool compressed_cache_record = false;
  try_load_cache(tex, cache, filename, record, compressed_cache_record,
                 options);

  if (tex == (Texture *)NULL) {
    // The texture was neither in the pool, nor found in the on-disk cache; it
    // needs to be loaded from its source image(s).
    gobj_cat.info()
      << "Loading texture " << filename << " and alpha component "
      << alpha_filename << endl;
    tex = ns_make_texture(filename.get_extension());
    if (!tex->read(filename, alpha_filename, primary_file_num_channels,
                   alpha_file_channel, 0, 0, false, read_mipmaps, NULL,
                   options)) {
      // This texture was not found or could not be read.
      report_texture_unreadable(filename);
      return NULL;
    }

    if (options.get_texture_flags() & LoaderOptions::TF_preload_simple) {
      tex->generate_simple_ram_image();
    }

    store_record = (record != (BamCacheRecord *)NULL);
  }

  if (cache->get_cache_compressed_textures() && tex->has_compression()) {
#ifndef HAVE_SQUISH
    bool needs_driver_compression = true;
#else
    bool needs_driver_compression = driver_compress_textures;
#endif // HAVE_SQUISH
    if (needs_driver_compression) {
      // We don't want to save the uncompressed version; we'll save the
      // compressed version when it becomes available.
      store_record = false;
      if (!compressed_cache_record) {
        tex->set_post_load_store_cache(true);
      }
    }

  } else if (!cache->get_cache_textures()) {
    // We don't want to save this texture.
    store_record = false;
  }

  // Set the original filenames, before we searched along the path.
  nassertr(tex != (Texture *)NULL, NULL);
  tex->set_filename(orig_filename);
  tex->set_fullpath(filename);
  tex->set_alpha_filename(orig_alpha_filename);
  tex->set_alpha_fullpath(alpha_filename);
  tex->_texture_pool_key = filename;

  {
    MutexHolder holder(_lock);

    // Now look again.
    Textures::const_iterator ti;
    ti = _textures.find(filename);
    if (ti != _textures.end()) {
      // This texture was previously loaded.
      Texture *tex = (*ti).second;
      nassertr(!tex->get_fullpath().empty(), tex);
      return tex;
    }

    _textures[filename] = tex;
  }

  if (store_record && tex->is_cacheable()) {
    // Store the on-disk cache record for next time.
    record->set_data(tex);
    cache->store(record);
  }

  if (!(options.get_texture_flags() & LoaderOptions::TF_preload)) {
    // And now drop the RAM until we need it.
    tex->clear_ram_image();
  }

  nassertr(!tex->get_fullpath().empty(), tex);

  // Finally, apply any post-loading texture filters.
  tex = post_load(tex);

  return tex;
}

/**
 * The nonstatic implementation of load_3d_texture().
 */
Texture *TexturePool::
ns_load_3d_texture(const Filename &filename_pattern,
                   bool read_mipmaps, const LoaderOptions &options) {
  Filename orig_filename(filename_pattern);
  orig_filename.set_pattern(true);

  Filename filename;
  {
    MutexHolder holder(_lock);
    resolve_filename(filename, orig_filename, read_mipmaps, options);

    Textures::const_iterator ti;
    ti = _textures.find(filename);
    if (ti != _textures.end()) {
      if ((*ti).second->get_texture_type() == Texture::TT_3d_texture) {
        // This texture was previously loaded, as a 3d texture
        return (*ti).second;
      }
    }
  }

  PT(Texture) tex;
  PT(BamCacheRecord) record;
  bool store_record = false;

  BamCache *cache = BamCache::get_global_ptr();
  bool compressed_cache_record = false;
  try_load_cache(tex, cache, filename, record, compressed_cache_record,
                 options);

  if (tex == (Texture *)NULL ||
      tex->get_texture_type() != Texture::TT_3d_texture) {
    // The texture was neither in the pool, nor found in the on-disk cache; it
    // needs to be loaded from its source image(s).
    gobj_cat.info()
      << "Loading 3-d texture " << filename << "\n";
    tex = ns_make_texture(filename.get_extension());
    tex->setup_3d_texture();
    if (!tex->read(filename, 0, 0, true, read_mipmaps, options)) {
      // This texture was not found or could not be read.
      report_texture_unreadable(filename);
      return NULL;
    }
    store_record = (record != (BamCacheRecord *)NULL);
  }

  if (cache->get_cache_compressed_textures() && tex->has_compression()) {
#ifndef HAVE_SQUISH
    bool needs_driver_compression = true;
#else
    bool needs_driver_compression = driver_compress_textures;
#endif // HAVE_SQUISH
    if (needs_driver_compression) {
      // We don't want to save the uncompressed version; we'll save the
      // compressed version when it becomes available.
      store_record = false;
      if (!compressed_cache_record) {
        tex->set_post_load_store_cache(true);
      }
    }

  } else if (!cache->get_cache_textures()) {
    // We don't want to save this texture.
    store_record = false;
  }

  // Set the original filename, before we searched along the path.
  nassertr(tex != (Texture *)NULL, NULL);
  tex->set_filename(filename_pattern);
  tex->set_fullpath(filename);
  tex->_texture_pool_key = filename;

  {
    MutexHolder holder(_lock);

    // Now look again.
    Textures::const_iterator ti;
    ti = _textures.find(filename);
    if (ti != _textures.end()) {
      if ((*ti).second->get_texture_type() == Texture::TT_3d_texture) {
        // This texture was previously loaded, as a 3d texture
        return (*ti).second;
      }
    }

    _textures[filename] = tex;
  }

  if (store_record && tex->is_cacheable()) {
    // Store the on-disk cache record for next time.
    record->set_data(tex);
    cache->store(record);
  }

  nassertr(!tex->get_fullpath().empty(), tex);
  return tex;
}

/**
 * The nonstatic implementation of load_2d_texture_array().
 */
Texture *TexturePool::
ns_load_2d_texture_array(const Filename &filename_pattern,
                         bool read_mipmaps, const LoaderOptions &options) {
  Filename orig_filename(filename_pattern);
  orig_filename.set_pattern(true);

  Filename filename;
  Filename unique_filename; //differentiate 3d-textures from 2d-texture arrays
  {
    MutexHolder holder(_lock);
    resolve_filename(filename, orig_filename, read_mipmaps, options);
    // Differentiate from preloaded 3d textures
    unique_filename = filename + ".2DARRAY";

    Textures::const_iterator ti;
    ti = _textures.find(unique_filename);
    if (ti != _textures.end()) {
      if ((*ti).second->get_texture_type() == Texture::TT_2d_texture_array) {
        // This texture was previously loaded, as a 2d texture array
        return (*ti).second;
      }
    }
  }

  PT(Texture) tex;
  PT(BamCacheRecord) record;
  bool store_record = false;

  BamCache *cache = BamCache::get_global_ptr();
  bool compressed_cache_record = false;
  try_load_cache(tex, cache, filename, record, compressed_cache_record,
                 options);

  if (tex == (Texture *)NULL ||
      tex->get_texture_type() != Texture::TT_2d_texture_array) {
    // The texture was neither in the pool, nor found in the on-disk cache; it
    // needs to be loaded from its source image(s).
    gobj_cat.info()
      << "Loading 2-d texture array " << filename << "\n";
    tex = ns_make_texture(filename.get_extension());
    tex->setup_2d_texture_array();
    if (!tex->read(filename, 0, 0, true, read_mipmaps, options)) {
      // This texture was not found or could not be read.
      report_texture_unreadable(filename);
      return NULL;
    }
    store_record = (record != (BamCacheRecord *)NULL);
  }

  if (cache->get_cache_compressed_textures() && tex->has_compression()) {
#ifndef HAVE_SQUISH
    bool needs_driver_compression = true;
#else
    bool needs_driver_compression = driver_compress_textures;
#endif // HAVE_SQUISH
    if (needs_driver_compression) {
      // We don't want to save the uncompressed version; we'll save the
      // compressed version when it becomes available.
      store_record = false;
      if (!compressed_cache_record) {
        tex->set_post_load_store_cache(true);
      }
    }

  } else if (!cache->get_cache_textures()) {
    // We don't want to save this texture.
    store_record = false;
  }

  // Set the original filename, before we searched along the path.
  nassertr(tex != (Texture *)NULL, NULL);
  tex->set_filename(filename_pattern);
  tex->set_fullpath(filename);
  tex->_texture_pool_key = filename;

  {
    MutexHolder holder(_lock);

    // Now look again.
    Textures::const_iterator ti;
    ti = _textures.find(unique_filename);
    if (ti != _textures.end()) {
      if ((*ti).second->get_texture_type() == Texture::TT_2d_texture_array) {
        // This texture was previously loaded, as a 2d texture array
        return (*ti).second;
      }
    }

    _textures[unique_filename] = tex;
  }

  if (store_record && tex->is_cacheable()) {
    // Store the on-disk cache record for next time.
    record->set_data(tex);
    cache->store(record);
  }

  nassertr(!tex->get_fullpath().empty(), tex);
  return tex;
}

/**
 * The nonstatic implementation of load_cube_map().
 */
Texture *TexturePool::
ns_load_cube_map(const Filename &filename_pattern, bool read_mipmaps,
                 const LoaderOptions &options) {
  Filename orig_filename(filename_pattern);
  orig_filename.set_pattern(true);

  Filename filename;
  {
    MutexHolder holder(_lock);
    resolve_filename(filename, orig_filename, read_mipmaps, options);

    Textures::const_iterator ti;
    ti = _textures.find(filename);
    if (ti != _textures.end()) {
      // This texture was previously loaded.
      return (*ti).second;
    }
  }

  PT(Texture) tex;
  PT(BamCacheRecord) record;
  bool store_record = false;

  BamCache *cache = BamCache::get_global_ptr();
  bool compressed_cache_record = false;
  try_load_cache(tex, cache, filename, record, compressed_cache_record,
                 options);

  if (tex == (Texture *)NULL ||
      tex->get_texture_type() != Texture::TT_cube_map) {
    // The texture was neither in the pool, nor found in the on-disk cache; it
    // needs to be loaded from its source image(s).
    gobj_cat.info()
      << "Loading cube map texture " << filename << "\n";
    tex = ns_make_texture(filename.get_extension());
    tex->setup_cube_map();
    if (!tex->read(filename, 0, 0, true, read_mipmaps, options)) {
      // This texture was not found or could not be read.
      report_texture_unreadable(filename);
      return NULL;
    }
    store_record = (record != (BamCacheRecord *)NULL);
  }

  if (cache->get_cache_compressed_textures() && tex->has_compression()) {
#ifndef HAVE_SQUISH
    bool needs_driver_compression = true;
#else
    bool needs_driver_compression = driver_compress_textures;
#endif // HAVE_SQUISH
    if (needs_driver_compression) {
      // We don't want to save the uncompressed version; we'll save the
      // compressed version when it becomes available.
      store_record = false;
      if (!compressed_cache_record) {
        tex->set_post_load_store_cache(true);
      }
    }

  } else if (!cache->get_cache_textures()) {
    // We don't want to save this texture.
    store_record = false;
  }

  // Set the original filename, before we searched along the path.
  nassertr(tex != (Texture *)NULL, NULL);
  tex->set_filename(filename_pattern);
  tex->set_fullpath(filename);
  tex->_texture_pool_key = unique_filename;

  {
    MutexHolder holder(_lock);

    // Now look again.
    Textures::const_iterator ti;
    ti = _textures.find(filename);
    if (ti != _textures.end()) {
      // This texture was previously loaded.
      return (*ti).second;
    }

    _textures[filename] = tex;
  }

  if (store_record && tex->is_cacheable()) {
    // Store the on-disk cache record for next time.
    record->set_data(tex);
    cache->store(record);
  }

  nassertr(!tex->get_fullpath().empty(), tex);
  return tex;
}

/**
 * The nonstatic implementation of get_normalization_cube_map().
 */
Texture *TexturePool::
ns_get_normalization_cube_map(int size) {
  MutexHolder holder(_lock);

  if (_normalization_cube_map == (Texture *)NULL) {
    _normalization_cube_map = new Texture("normalization_cube_map");
  }
  if (_normalization_cube_map->get_x_size() < size ||
      _normalization_cube_map->get_texture_type() != Texture::TT_cube_map) {
    _normalization_cube_map->generate_normalization_cube_map(size);
  }

  return _normalization_cube_map;
}

/**
 * The nonstatic implementation of get_alpha_scale_map().
 */
Texture *TexturePool::
ns_get_alpha_scale_map() {
  MutexHolder holder(_lock);

  if (_alpha_scale_map == (Texture *)NULL) {
    _alpha_scale_map = new Texture("alpha_scale_map");
    _alpha_scale_map->generate_alpha_scale_map();
  }

  return _alpha_scale_map;
}

/**
 * The nonstatic implementation of add_texture().
 */
void TexturePool::
ns_add_texture(Texture *tex) {
  PT(Texture) keep = tex;
  MutexHolder holder(_lock);

  if (!tex->_texture_pool_key.empty()) {
    ns_release_texture(tex);
  }
  string filename = tex->get_fullpath();
  if (filename.empty()) {
    gobj_cat.error() << "Attempt to call add_texture() on an unnamed texture.\n";
  }

  // We blow away whatever texture was there previously, if any.
  tex->_texture_pool_key = filename;
  _textures[filename] = tex;
  nassertv(!tex->get_fullpath().empty());
}

/**
 * The nonstatic implementation of release_texture().
 */
void TexturePool::
ns_release_texture(Texture *tex) {
  MutexHolder holder(_lock);

  if (!tex->_texture_pool_key.empty()) {
    Textures::iterator ti;
    ti = _textures.find(tex->_texture_pool_key);
    if (ti != _textures.end() && (*ti).second == tex) {
      _textures.erase(ti);
    }
    tex->_texture_pool_key = string();
  }

  // Blow away the cache of resolved relative filenames.
  _relpath_lookup.clear();
}

/**
 * The nonstatic implementation of release_all_textures().
 */
void TexturePool::
ns_release_all_textures() {
  MutexHolder holder(_lock);

  Textures::iterator ti;
  for (ti = _textures.begin(); ti != _textures.end(); ++ti) {
    Texture *tex = (*ti).second;
    tex->_texture_pool_key = string();
  }

  _textures.clear();
  _normalization_cube_map = NULL;

  // Blow away the cache of resolved relative filenames.
  _relpath_lookup.clear();
}

/**
 * The nonstatic implementation of garbage_collect().
 */
int TexturePool::
ns_garbage_collect() {
  MutexHolder holder(_lock);

  int num_released = 0;
  Textures new_set;

  Textures::iterator ti;
  for (ti = _textures.begin(); ti != _textures.end(); ++ti) {
    Texture *tex = (*ti).second;
    if (tex->get_ref_count() == 1) {
      if (gobj_cat.is_debug()) {
        gobj_cat.debug()
          << "Releasing " << (*ti).first << "\n";
      }
      ++num_released;
      tex->_texture_pool_key = string();
    } else {
      new_set.insert(new_set.end(), *ti);
    }
  }

  _textures.swap(new_set);

  if (_normalization_cube_map != (Texture *)NULL &&
      _normalization_cube_map->get_ref_count() == 1) {
    if (gobj_cat.is_debug()) {
      gobj_cat.debug()
        << "Releasing normalization cube map\n";
    }
    ++num_released;
    _normalization_cube_map = NULL;
  }

  return num_released;
}

/**
 * The nonstatic implementation of list_contents().
 */
void TexturePool::
ns_list_contents(ostream &out) const {
  MutexHolder holder(_lock);

  int total_size;
  int total_ram_size;
  Textures::const_iterator ti;

  out << "texture pool contents:\n";

  total_size = 0;
  total_ram_size = 0;
  for (ti = _textures.begin(); ti != _textures.end(); ++ti) {
    Texture *tex = (*ti).second;
    out << (*ti).first << "\n";
    out << "  (count = " << tex->get_ref_count()
        << ", ram  = " << tex->get_ram_image_size()
        << ", size = " << tex->get_ram_page_size()
        << ", w = " << tex->get_x_size()
        << ", h = " << tex->get_y_size()
        << ")\n";
    nassertv(tex->_texture_pool_key == (*ti).first);
    total_ram_size += tex->get_ram_image_size();
    total_size += tex->get_ram_page_size();
  }

  out << "total number of textures: " << _textures.size() << "\n";
  out << "texture pool ram : " << total_ram_size << "\n";
  out << "texture pool size: " << total_size << "\n";
  out << "texture pool size - texture pool ram: " << total_size - total_ram_size << "\n";
}

/**
 * The nonstatic implementation of find_texture().
 */
Texture *TexturePool::
ns_find_texture(const string &name) const {
  MutexHolder holder(_lock);
  GlobPattern glob(name);

  Textures::const_iterator ti;
  for (ti = _textures.begin(); ti != _textures.end(); ++ti) {
    Texture *tex = (*ti).second;
    if (glob.matches(tex->get_name())) {
      return tex;
    }
  }

  return NULL;
}

/**
 * The nonstatic implementation of find_all_textures().
 */
TextureCollection TexturePool::
ns_find_all_textures(const string &name) const {
  MutexHolder holder(_lock);
  TextureCollection result;
  GlobPattern glob(name);

  Textures::const_iterator ti;
  for (ti = _textures.begin(); ti != _textures.end(); ++ti) {
    Texture *tex = (*ti).second;
    if (glob.matches(tex->get_name())) {
      result.add_texture(tex);
    }
  }

  return result;
}

/**
 * Creates a new Texture object of the appropriate type for the indicated
 * filename extension, according to the types that have been registered via
 * register_texture_type().
 */
PT(Texture) TexturePool::
ns_make_texture(const string &extension) const {
  MakeTextureFunc *func = get_texture_type(extension);
  if (func != NULL) {
    return func();
  }

  // We don't know what kind of file type this is; return an ordinary Texture
  // in case it's an image file with no extension.
  return new Texture;
}

/**
 * Searches for the indicated filename along the model path.  If the filename
 * was previously searched for, doesn't search again, as an optimization.
 * Assumes _lock is held.
 */
void TexturePool::
resolve_filename(Filename &new_filename, const Filename &orig_filename,
                 bool read_mipmaps, const LoaderOptions &options) {
  if (!_fake_texture_image.empty()) {
    new_filename = _fake_texture_image;
    return;
  }

  RelpathLookup::iterator rpi = _relpath_lookup.find(orig_filename);
  if (rpi != _relpath_lookup.end()) {
    new_filename = (*rpi).second;
    return;
  }

  new_filename = orig_filename;
  if (read_mipmaps || (options.get_texture_flags() & LoaderOptions::TF_multiview)) {
    new_filename.set_pattern(true);
  }

  VirtualFileSystem *vfs = VirtualFileSystem::get_global_ptr();
  vfs->resolve_filename(new_filename, get_model_path());

  _relpath_lookup[orig_filename] = new_filename;
}

/**
 * Attempts to load the texture from the cache record.
 */
void TexturePool::
try_load_cache(PT(Texture) &tex, BamCache *cache, const Filename &filename,
               PT(BamCacheRecord) &record, bool &compressed_cache_record,
               const LoaderOptions &options) {
  if (tex == (Texture *)NULL) {
    // The texture was not supplied by a texture filter.  See if it can be
    // found in the on-disk cache, if it is active.
    if ((cache->get_cache_textures() || cache->get_cache_compressed_textures()) && !textures_header_only) {

      // Call ns_make_texture() on the file extension and create a dummy
      // texture object we can call ensure_loaded_type() on.  We don't need to
      // keep this object around after this call, since we'll be creating a
      // new one below.  I know this is a bit hacky.
      string ext = downcase(filename.get_extension());
      PT(Texture) dummy = ns_make_texture(ext);
      dummy->ensure_loader_type(filename);
      dummy.clear();

      record = cache->lookup(filename, "txo");
      if (record != (BamCacheRecord *)NULL) {
        if (record->has_data()) {
          tex = DCAST(Texture, record->get_data());
          compressed_cache_record = (tex->get_ram_image_compression() != Texture::CM_off);
          int x_size = tex->get_orig_file_x_size();
          int y_size = tex->get_orig_file_y_size();
          tex->adjust_this_size(x_size, y_size, filename.get_basename(), true);

          if (!cache->get_cache_textures() && !compressed_cache_record) {
            // We're not supposed to be caching uncompressed textures.
            if (gobj_cat.is_debug()) {
              gobj_cat.debug()
                << "Not caching uncompressed texture " << *tex << "\n";
            }
            tex = NULL;
            record = NULL;

          } else if (x_size != tex->get_x_size() ||
                     y_size != tex->get_y_size()) {
            // The cached texture no longer matches our expected size (the
            // resizing config variables must have changed). We'll have to
            // reload the texture from its original file so we can rebuild the
            // cache.
            if (gobj_cat.is_debug()) {
              gobj_cat.debug()
                << "Cached texture " << *tex << " has size "
                << tex->get_x_size() << " x " << tex->get_y_size()
                << " instead of " << x_size << " x " << y_size
                << "; dropping cache.\n";
            }
            tex = NULL;

          } else if (!tex->has_compression() && tex->get_ram_image_compression() != Texture::CM_off) {
            // This texture shouldn't be compressed, but it is.  Go reload it.
            if (gobj_cat.is_debug()) {
              gobj_cat.debug()
                << "Cached texture " << *tex
                << " is compressed in cache; dropping cache.\n";
            }
            tex = NULL;

          } else {
            gobj_cat.info()
              << "Texture " << filename << " found in disk cache.\n";
            if ((options.get_texture_flags() & LoaderOptions::TF_preload_simple) &&
                !tex->has_simple_ram_image()) {
              tex->generate_simple_ram_image();
            }
            if (!(options.get_texture_flags() & LoaderOptions::TF_preload)) {
              // But drop the RAM until we need it.
              tex->clear_ram_image();

            } else {
              bool was_compressed = (tex->get_ram_image_compression() != Texture::CM_off);
              if (tex->consider_auto_process_ram_image(tex->uses_mipmaps(), true)) {
                bool is_compressed = (tex->get_ram_image_compression() != Texture::CM_off);
                if (!was_compressed && is_compressed &&
                    cache->get_cache_compressed_textures()) {
                  // We've re-compressed the image after loading it from the
                  // cache.  To keep the cache current, rewrite it to the
                  // cache now, in its newly compressed form.
                  record->set_data(tex);
                  cache->store(record);
                  compressed_cache_record = true;
                }
              }
            }
            tex->set_keep_ram_image(false);
          }
        } else {
          if (!cache->get_cache_textures()) {
            // This texture has no actual record, and therefore no compressed
            // record (yet).  And we're not supposed to be caching
            // uncompressed textures.
            if (gobj_cat.is_debug()) {
              gobj_cat.debug()
                << "Not caching uncompressed texture\n";
            }
            record = NULL;
          }
        }
      }
    }
  }
}

/**
 * Prints a suitable error message when a texture could not be loaded.
 */
void TexturePool::
report_texture_unreadable(const Filename &filename) const {
  VirtualFileSystem *vfs = VirtualFileSystem::get_global_ptr();
  bool has_hash = (filename.get_fullpath().find('#') != string::npos);
  if (!has_hash && !vfs->exists(filename)) {
    if (filename.is_local()) {
      // The file doesn't exist, and it wasn't fully-qualified--therefore, it
      // wasn't found along either search path.
      gobj_cat.error()
        << "Unable to find texture \"" << filename << "\""
        << " on model-path " << get_model_path() <<"\n";
    } else {
      // A fully-specified filename is not searched along the path, so don't
      // mislead the user with the error message.
      gobj_cat.error()
        << "Texture \"" << filename << "\" does not exist.\n";
    }

  } else {
    // The file exists, but it couldn't be read for some reason.
    if (!has_hash) {
      gobj_cat.error()
        << "Texture \"" << filename << "\" exists but cannot be read.\n";
    } else {
      // If the filename contains a hash, we'll be noncommittal about whether
      // it exists or not.
      gobj_cat.error()
        << "Texture \"" << filename << "\" cannot be read.\n";
    }

    // Maybe the filename extension is unknown.
    MakeTextureFunc *func = get_texture_type(filename.get_extension());
    if (func == (MakeTextureFunc *)NULL) {
      gobj_cat.error()
        << "Texture extension \"" << filename.get_extension()
        << "\" is unknown.  Supported texture types:\n";
      write_texture_types(gobj_cat.error(false), 2);
    }
  }
}

/**
 * Invokes pre_load() on all registered filters until one returns non-NULL;
 * returns NULL if there are no registered filters or if all registered
 * filters returned NULL.
 */
PT(Texture) TexturePool::
pre_load(const Filename &orig_filename, const Filename &orig_alpha_filename,
         int primary_file_num_channels, int alpha_file_channel,
         bool read_mipmaps, const LoaderOptions &options) {
  PT(Texture) tex;

  MutexHolder holder(_lock);

  FilterRegistry::iterator fi;
  for (fi = _filter_registry.begin();
       fi != _filter_registry.end();
       ++fi) {
    tex = (*fi)->pre_load(orig_filename, orig_alpha_filename,
                          primary_file_num_channels, alpha_file_channel,
                          read_mipmaps, options);
    if (tex != (Texture *)NULL) {
      return tex;
    }
  }

  return tex;
}

/**
 * Invokes post_load() on all registered filters.
 */
PT(Texture) TexturePool::
post_load(Texture *tex) {
  PT(Texture) result = tex;

  MutexHolder holder(_lock);

  FilterRegistry::iterator fi;
  for (fi = _filter_registry.begin();
       fi != _filter_registry.end();
       ++fi) {
    result = (*fi)->post_load(result);
  }

  return result;
}


/**
 * Loads up all of the dll's named by the texture-filter Config.prc variable.
 */
void TexturePool::
load_filters() {
  ConfigVariableList texture_filter
    ("texture-filter",
     PRC_DESC("Names one or more external libraries that should be loaded for the "
              "purposes of performing texture filtering.  This variable may be repeated several "
              "times.  As in load-display, the actual library filename is derived by "
              "prefixing 'lib' to the specified name."));

  int num_aux = texture_filter.get_num_unique_values();
  for (int i = 0; i < num_aux; i++) {
    string name = texture_filter.get_unique_value(i);

    Filename dlname = Filename::dso_filename("lib" + name + ".so");
    gobj_cat->info()
      << "loading texture filter: " << dlname.to_os_specific() << endl;
    void *tmp = load_dso(get_plugin_path().get_value(), dlname);
    if (tmp == (void *)NULL) {
      gobj_cat.info()
        << "Unable to load: " << load_dso_error() << endl;
    }
  }
}