// Filename: geomVertexReader.h
// Created by:  drose (25Mar05)
//
////////////////////////////////////////////////////////////////////
//
// PANDA 3D SOFTWARE
// Copyright (c) 2001 - 2004, 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://etc.cmu.edu/panda3d/docs/license/ .
//
// To contact the maintainers of this program write to
// panda3d-general@lists.sourceforge.net .
//
////////////////////////////////////////////////////////////////////

#ifndef GEOMVERTEXREADER_H
#define GEOMVERTEXREADER_H

#include "pandabase.h"
#include "geomVertexData.h"
#include "geomVertexColumn.h"
#include "internalName.h"
#include "luse.h"
#include "pointerTo.h"

////////////////////////////////////////////////////////////////////
//       Class : GeomVertexReader
// Description : This object provides a high-level interface for
//               quickly reading a sequence of numeric values from a
//               vertex table. 
//
//               It is particularly optimized for reading a single
//               column of data values for a series of vertices,
//               without changing columns between each number.
//               Although you can also use one GeomVertexReader to
//               read across the columns if it is convenient, by
//               calling set_column() repeatedly at each vertex, it is
//               faster to read down the columns, and to use a
//               different GeomVertexReader for each column.
//
//               Note that a GeomVertexReader does not keep a
//               reference count to the actual vertex data buffer (it
//               grabs the current data buffer from the GeomVertexData
//               whenever set_column() is called).  This means that it
//               is important not to keep a GeomVertexReader object
//               around over a long period of time in which the data
//               buffer is likely to be deallocated; it is intended
//               for making a quick pass over the data in one session.
//
//               It also means that you should create any
//               GeomVertexWriters *before* creating GeomVertexReaders
//               on the same data, since the writer itself might cause
//               the vertex buffer to be deallocated.  Better yet, use
//               a GeomVertexRewriter if you are going to create both
//               of them anyway.
////////////////////////////////////////////////////////////////////
class EXPCL_PANDA GeomVertexReader : public GeomEnums {
PUBLISHED:
  INLINE GeomVertexReader(const GeomVertexData *vertex_data);
  INLINE GeomVertexReader(const GeomVertexData *vertex_data,
                          const string &name);
  INLINE GeomVertexReader(const GeomVertexData *vertex_data,
                          const InternalName *name);
  INLINE GeomVertexReader(const GeomVertexArrayData *array_data);
  INLINE GeomVertexReader(const GeomVertexArrayData *array_data, 
                          int column);
  INLINE GeomVertexReader(const GeomVertexReader &copy);
  INLINE void operator = (const GeomVertexReader &copy);
  INLINE ~GeomVertexReader();

  INLINE const GeomVertexData *get_vertex_data() const;
  INLINE const GeomVertexArrayData *get_array_data() const;

  INLINE bool set_column(int column);
  INLINE bool set_column(const string &name);
  INLINE bool set_column(const InternalName *name);
  bool set_column(int array, const GeomVertexColumn *column);

  INLINE bool has_column() const;
  INLINE int get_array() const;
  INLINE const GeomVertexColumn *get_column() const;

  INLINE void set_row(int row);

  INLINE int get_start_row() const;
  INLINE int get_read_row() const;
  INLINE bool is_at_end() const;

  INLINE float get_data1f();
  INLINE const LVecBase2f &get_data2f();
  INLINE const LVecBase3f &get_data3f();
  INLINE const LVecBase4f &get_data4f();

  INLINE int get_data1i();
  INLINE const int *get_data2i();
  INLINE const int *get_data3i();
  INLINE const int *get_data4i();

private:
  void initialize();

  INLINE void set_pointer(int row);
  INLINE void quick_set_pointer(int row);
  INLINE const unsigned char *inc_pointer();

  // It is important that we only store *one* of the following two
  // pointers.  If we are storing a GeomVertexData/array index, we
  // must not keep a pointer to the particular ArrayData we are
  // working on (if we do, it may result in an extra copy of the data
  // due to holding the reference count).
  CPT(GeomVertexData) _vertex_data;
  int _array;
  CPT(GeomVertexArrayData) _array_data;

  GeomVertexColumn::Packer *_packer;
  int _stride;

  const unsigned char *_pointer_begin;
  const unsigned char *_pointer_end;
  const unsigned char *_pointer;

  int _start_row;

#ifndef NDEBUG
  // This is defined just for the benefit of having something non-NULL
  // to return from a nassertr() call.
  static const unsigned char empty_buffer[100];
#endif
};

#include "geomVertexReader.I"

#endif