// newmat.hxx -- a material in the scene graph.
// TODO: this class needs to be renamed.
//
// Written by Curtis Olson, started May 1998.
// Overhauled by David Megginson, December 2001
//
// Copyright (C) 1998 - 2000  Curtis L. Olson  - curt@flightgear.org
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
//
// $Id$


#ifndef _NEWMAT_HXX
#define _NEWMAT_HXX

#ifndef __cplusplus                                                          
# error This library requires C++
#endif                                   

#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

#ifdef HAVE_WINDOWS_H
#  include <windows.h>
#endif

#include <plib/sg.h>
#include <plib/ssg.h>

#include <simgear/compiler.h>
#include <simgear/misc/props.hxx>

#include <GL/glut.h>

#include STL_STRING      // Standard C++ string library

SG_USING_STD(string);


/**
 * A material in the scene graph.
 *
 * A material represents information about a single surface type
 * in the 3D scene graph, including texture, colour, lighting,
 * tiling, and so on; most of the materials in FlightGear are
 * defined in the $FG_ROOT/materials.xml file, and can be changed
 * at runtime.
 */
class FGNewMat {

public:


  //////////////////////////////////////////////////////////////////////
  // Inner classes.
  //////////////////////////////////////////////////////////////////////

  class ObjectGroup;

  /**
   * A randomly-placeable object.
   *
   * FGNewMat uses this class to keep track of the model(s) and
   * parameters for a single instance of a randomly-placeable object.
   * The object can have more than one variant model (i.e. slightly
   * different shapes of trees), but they are considered equivalent
   * and interchangeable.
   */
  class Object
  {
  public:

    /**
     * The heading type for a randomly-placed object.
     */
    enum HeadingType {
      HEADING_FIXED,
      HEADING_BILLBOARD,
      HEADING_RANDOM
    };


    /**
     * Get the number of variant models available for the object.
     *
     * @return The number of variant models.
     */
    int get_model_count () const;


    /**
     * Get a specific variant model for the object.
     *
     * @param index The index of the model.
     * @return The model.
     */
    ssgEntity * get_model (int index) const;


    /**
     * Get a randomly-selected variant model for the object.
     *
     * @return A randomly select model from the variants.
     */
    ssgEntity * get_random_model () const;


    /**
     * Get the average number of meters^2 occupied by each instance.
     *
     * @return The coverage in meters^2.
     */
    double get_coverage_m2 () const;


    /**
     * Get the heading type for the object.
     *
     * @return The heading type.
     */
    HeadingType get_heading_type () const;

  protected:

    friend class ObjectGroup;

    Object (const SGPropertyNode * node, double range_m);

    virtual ~Object ();

  private:

    /**
     * Actually load the models.
     *
     * This class uses lazy loading so that models won't be held
     * in memory for materials that are never referenced.
     */
    void load_models () const;

    vector<string> _paths;
    mutable vector<ssgEntity *> _models;
    mutable bool _models_loaded;
    double _coverage_m2;
    double _range_m;
    HeadingType _heading_type;
  };


  /**
   * A collection of related objects with the same visual range.
   *
   * Grouping objects with the same range together significantly
   * reduces the memory requirements of randomly-placed objects.
   * Each FGNewMat instance keeps a (possibly-empty) list of
   * object groups for placing randomly on the scenery.
   */
  class ObjectGroup
  {
  public:
    virtual ~ObjectGroup ();


    /**
     * Get the visual range of the object in meters.
     *
     * @return The visual range.
     */
    double get_range_m () const;


    /**
     * Get the number of objects in the group.
     *
     * @return The number of objects.
     */
    int get_object_count () const;


    /**
     * Get a specific object.
     *
     * @param index The object's index, zero-based.
     * @return The object selected.
     */
    Object * get_object (int index) const;

  protected:

    friend class FGNewMat;

    ObjectGroup (SGPropertyNode * node);

  private:

    double _range_m;
    vector<Object *> _objects;

  };




  ////////////////////////////////////////////////////////////////////
  // Public Constructors.
  ////////////////////////////////////////////////////////////////////

  /**
   * Construct a material from a set of properties.
   *
   * @param props A property node containing subnodes with the
   * state information for the material.  This node is usually
   * loaded from the $FG_ROOT/materials.xml file.
   */
  FGNewMat (const SGPropertyNode * props);


  /**
   * Construct a material from an absolute texture path.
   *
   * @param texture_path A string containing an absolute path
   * to a texture file (usually RGB).
   */
  FGNewMat (const string &texpath);


  /**
   * Construct a material around an existing SSG state.
   *
   * This constructor allows the application to create a custom,
   * low-level state for the scene graph and wrap a material around
   * it.  Note: the pointer ownership is transferred to the material.
   *
   * @param s The SSG state for this material.
   */
  FGNewMat (ssgSimpleState * s);

  /**
   * Destructor.
   */
  virtual ~FGNewMat ( void );



  ////////////////////////////////////////////////////////////////////
  // Public methods.
  ////////////////////////////////////////////////////////////////////

  /**
   * Force the texture to load if it hasn't already.
   *
   * @return true if the texture loaded, false if it was loaded
   * already.
   */
  virtual bool load_texture ();


  /**
   * Get the textured state.
   */
  virtual inline ssgSimpleState *get_textured () { return textured; }


  /**
   * Get the xsize of the texture, in meters.
   */
  virtual inline double get_xsize() const { return xsize; }


  /**
   * Get the ysize of the texture, in meters.
   */
  virtual inline double get_ysize() const { return ysize; }


  /**
   * Get the light coverage.
   *
   * A smaller number means more generated night lighting.
   *
   * @return The area (m^2?) covered by each light.
   */
  virtual inline double get_light_coverage () const { return light_coverage; }


  /**
   * Get the number of randomly-placed objects defined for this material.
   */
  virtual int get_object_group_count () const { return object_groups.size(); }


  /**
   * Get a randomly-placed object for this material.
   */
  virtual ObjectGroup * get_object_group (int index) const {
    return object_groups[index];
  }


  /**
   * Get the current state.
   */
  virtual inline ssgStateSelector *get_state () const { return state; }


  /**
   * Increment the reference count for this material.
   *
   * A material with 0 references may be deleted by the
   * material library.
   */
  virtual inline void ref () { refcount++; }


  /**
   * Decrement the reference count for this material.
   */
  virtual inline void deRef () { refcount--; }


  /**
   * Get the reference count for this material.
   *
   * @return The number of references (0 if none).
   */
  virtual inline int getRef () const { return refcount; }

protected:


  ////////////////////////////////////////////////////////////////////
  // Protected methods.
  ////////////////////////////////////////////////////////////////////

  /**
   * Initialization method, invoked by all public constructors.
   */
  virtual void init();


private:


  ////////////////////////////////////////////////////////////////////
  // Internal state.
  ////////////////////////////////////////////////////////////////////

  // names
  string texture_path;

  // pointers to ssg states
  ssgStateSelector *state;
  ssgSimpleState *textured;
  ssgSimpleState *nontextured;

  // texture size
  double xsize, ysize;

  // wrap texture?
  bool wrapu, wrapv;

  // use mipmapping?
  int mipmap;

  // coverage of night lighting.
  double light_coverage;

  // material properties
  sgVec4 ambient, diffuse, specular, emission;

  // true if texture loading deferred, and not yet loaded
  bool texture_loaded;

  vector<ObjectGroup *> object_groups;

  // ref count so we can properly delete if we have multiple
  // pointers to this record
  int refcount;



  ////////////////////////////////////////////////////////////////////
  // Internal constructors and methods.
  ////////////////////////////////////////////////////////////////////

  FGNewMat (const FGNewMat &mat); // unimplemented

  void read_properties (const SGPropertyNode * props);
  void build_ssg_state(bool defer_tex_load = false);
  void set_ssg_state( ssgSimpleState *s );


};

#endif // _NEWMAT_HXX