/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkOpenGLRGBTable.h

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/

#ifndef __vtkOpenGLRGBTable_h_
#define __vtkOpenGLRGBTable_h_

#include <vtkColorTransferFunction.h>
#include <vtk_glew.h>

//----------------------------------------------------------------------------
class vtkOpenGLRGBTable
{
public:
  //--------------------------------------------------------------------------
  vtkOpenGLRGBTable()
    {
    this->Loaded = false;
    this->LastLinearInterpolation = false;
    this->TexutureWidth = 1024;
    this->NumberOfColorComponents = 3;
    this->TextureId = 0;
    this->LastRange[0] = this->LastRange[1] = 0;
    this->Table = 0;
    }

  //--------------------------------------------------------------------------
  ~vtkOpenGLRGBTable()
    {
    if(this->TextureId!=0)
      {
      glDeleteTextures(1,&this->TextureId);
      this->TextureId=0;
      }
    if(this->Table!=0)
      {
      delete[] this->Table;
      this->Table=0;
      }
    }

  // Check if color transfer function texture is loaded.
  //--------------------------------------------------------------------------
  bool IsLoaded()
    {
    return this->Loaded;
    }

  // Bind texture.
  //--------------------------------------------------------------------------
  void Bind(int textureUnit = 1)
    {
    // Activate texture 1
    glActiveTexture(GL_TEXTURE0 + textureUnit);
    glBindTexture(GL_TEXTURE_1D, this->TextureId);
    }

  // Update color transfer function texture.
  //--------------------------------------------------------------------------
  void Update(vtkColorTransferFunction* scalarRGB,
              double range[2],
              bool linearInterpolation, int textureUnit = 1)
    {
    // Activate texture 1
    glActiveTexture(GL_TEXTURE0 + textureUnit);

    bool needUpdate = false;

    if(this->TextureId == 0)
      {
      glGenTextures(1, &this->TextureId);
      needUpdate = true;
      }

    if (range[0] != this->LastRange[0] || range[1] != this->LastRange[1])
      {
      needUpdate=true;
      }

    glBindTexture(GL_TEXTURE_1D, this->TextureId);
    if(needUpdate)
      {
      glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S,
                      GL_CLAMP_TO_EDGE);
      }
    if(scalarRGB->GetMTime() > this->BuildTime || needUpdate || !this->Loaded)
      {
      this->Loaded = false;

      // Create table if not created already
      if(this->Table==0)
        {
        this->Table = new float[this->TexutureWidth *
          this->NumberOfColorComponents];
        }

      scalarRGB->GetTable(range[0],range[1], this->TexutureWidth, this->Table);
      glTexImage1D(GL_TEXTURE_1D, 0, GL_RGB16, this->TexutureWidth, 0,
                   GL_RGB, GL_FLOAT, this->Table);

      this->Loaded = true;
      this->BuildTime.Modified();

      this->LastRange[0] = range[0];
      this->LastRange[1] = range[1];
      }

    needUpdate = needUpdate ||
      this->LastLinearInterpolation!=linearInterpolation;
    if (needUpdate)
      {
      this->LastLinearInterpolation = linearInterpolation;
      GLint value;
      if (linearInterpolation)
        {
        value = GL_LINEAR;
        }
      else
        {
        value = GL_NEAREST;
        }
      glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, value);
      glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, value);
      }

    glActiveTexture(GL_TEXTURE0);
    }

protected:

  bool Loaded;
  bool LastLinearInterpolation;

  int TexutureWidth;
  int NumberOfColorComponents;

  GLuint TextureId;

  double LastRange[2];
  float* Table;
  vtkTimeStamp BuildTime;
};

#endif // __vtkOpenGLRGBTable_h_
// VTK-HeaderTest-Exclude: vtkOpenGLRGBTable.h
