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

  Program:   Visualization Toolkit
  Module:    vtkStructuredGridLIC2D.cxx

  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.

=========================================================================*/
#include "vtkStructuredGridLIC2D.h"

#include "vtkFloatArray.h"
#include "vtkImageData.h"
#include "vtkImageNoiseSource.h"
#include "vtkInformation.h"
#include "vtkInformationVector.h"
#include "vtkDataTransferHelper.h"
#include "vtkFrameBufferObject.h"
#include "vtkLineIntegralConvolution2D.h"
#include "vtkShaderProgram2.h"
#include "vtkShader2.h"
#include "vtkShader2Collection.h"
#include "vtkUniformVariables.h"
#include "vtkStructuredExtent.h"
#include "vtkTextureObject.h"
#include "vtkObjectFactory.h"
#include "vtkOpenGLExtensionManager.h"
#include "vtkOpenGLRenderWindow.h"
#include "vtkPointData.h"
#include "vtkStreamingDemandDrivenPipeline.h"
#include "vtkOpenGLError.h"

#include "vtkPixelExtent.h"
#include "vtkPixelTransfer.h"
#include "vtkPixelBufferObject.h"

#include <cassert>
#include "vtkgl.h"

extern const char *vtkStructuredGridLIC2D_fs;

#define PRINTEXTENT(ext) \
  ext[0] << ", " << ext[1] << ", " << ext[2] << ", " << ext[3] << ", " << ext[4] << ", " << ext[5]

vtkStandardNewMacro(vtkStructuredGridLIC2D);
//----------------------------------------------------------------------------
vtkStructuredGridLIC2D::vtkStructuredGridLIC2D()
{
  this->Context = 0;
  this->Steps = 1;
  this->StepSize = 1.0;
  this->Magnification = 1;
  this->SetNumberOfInputPorts(2);
  this->SetNumberOfOutputPorts(2);
  this->OwnWindow  = false;
  this->FBOSuccess = 0;
  this->LICSuccess = 0;
  this->OpenGLExtensionsSupported = 0;

  this->NoiseSource = vtkImageNoiseSource::New();
  this->NoiseSource->SetWholeExtent(0, 127, 0, 127, 0, 0);
  this->NoiseSource->SetMinimum(0.0);
  this->NoiseSource->SetMaximum(1.0);
}

//----------------------------------------------------------------------------
vtkStructuredGridLIC2D::~vtkStructuredGridLIC2D()
{
  this->NoiseSource->Delete();
  this->SetContext( nullptr );
}

//----------------------------------------------------------------------------
vtkRenderWindow* vtkStructuredGridLIC2D::GetContext()
{
  return this->Context;
}

//----------------------------------------------------------------------------
int vtkStructuredGridLIC2D::SetContext( vtkRenderWindow * context )
{
  if ( this->Context == context )
  {
    return this->OpenGLExtensionsSupported;
  }

  if ( this->Context && this->OwnWindow )
  {
    this->Context->Delete();
    this->Context = nullptr;
  }
  this->OwnWindow = false;


  vtkOpenGLRenderWindow * openGLRenWin =
  vtkOpenGLRenderWindow::SafeDownCast( context );
  this->Context = openGLRenWin;

  if ( openGLRenWin )
  {
    vtkOpenGLExtensionManager * mgr = openGLRenWin->GetExtensionManager();

    // optional for texture objects.
    mgr->LoadSupportedExtension( "GL_EXT_texture_integer" );

    if (  !mgr->LoadSupportedExtension( "GL_VERSION_1_3" ) ||
          !mgr->LoadSupportedExtension( "GL_VERSION_1_2" ) ||
          !mgr->LoadSupportedExtension( "GL_VERSION_2_0" ) ||
          !mgr->LoadSupportedExtension( "GL_ARB_texture_float" ) ||
          !mgr->LoadSupportedExtension( "GL_ARB_color_buffer_float" ) ||
          !mgr->LoadSupportedExtension( "GL_ARB_texture_non_power_of_two" )
       )
    {
      vtkErrorMacro( "Required OpenGL extensions not supported." );
      mgr = nullptr;
      this->Context = 0;
      openGLRenWin  = nullptr;
      return 0;
    }

    mgr = nullptr;
  }

  openGLRenWin = nullptr;
  this->Modified();

  this->OpenGLExtensionsSupported = 1;
  return 1;
}

//----------------------------------------------------------------------------
// Description:
// Fill the input port information objects for this algorithm.  This
// is invoked by the first call to GetInputPortInformation for each
// port so subclasses can specify what they can handle.
// Redefined from the superclass.
int vtkStructuredGridLIC2D::FillInputPortInformation
  ( int port, vtkInformation * info )
{
  if ( port == 0 )
  {
    info->Set( vtkAlgorithm::INPUT_REQUIRED_DATA_TYPE(), "vtkStructuredGrid" );
    info->Set( vtkAlgorithm::INPUT_IS_REPEATABLE(), 0 );
    info->Set( vtkAlgorithm::INPUT_IS_OPTIONAL(),   0 );
  }
  else
  {
    info->Set( vtkAlgorithm::INPUT_REQUIRED_DATA_TYPE(), "vtkImageData" );
    info->Set( vtkAlgorithm::INPUT_IS_REPEATABLE(), 0 );
    info->Set( vtkAlgorithm::INPUT_IS_OPTIONAL(),   1 );
  }

  return 1;
}

// ----------------------------------------------------------------------------
// Description:
// Fill the output port information objects for this algorithm.
// This is invoked by the first call to GetOutputPortInformation for
// each port so subclasses can specify what they can handle.
// Redefined from the superclass.
int vtkStructuredGridLIC2D::FillOutputPortInformation
  ( int port, vtkInformation * info )
{
  if ( port == 0 )
  {
    // input+texcoords
    info->Set( vtkDataObject::DATA_TYPE_NAME(), "vtkStructuredGrid" );
  }
  else
  {
    // LIC texture
    info->Set( vtkDataObject::DATA_TYPE_NAME(), "vtkImageData" );
  }

  return 1;
}
//----------------------------------------------------------------------------
// We need to report output extent after taking into consideration the
// magnification.
int vtkStructuredGridLIC2D::RequestInformation(
  vtkInformation        * vtkNotUsed(request),
  vtkInformationVector ** inputVector,
  vtkInformationVector  * outputVector )
{
  int ext[6];
  double spacing[3];

  vtkInformation * inInfo  = inputVector[0]->GetInformationObject( 0 );
  vtkInformation * outInfo = outputVector->GetInformationObject( 1 );

  inInfo->Get( vtkStreamingDemandDrivenPipeline::WHOLE_EXTENT(), ext );

  spacing[0] = 1.0;
  spacing[1] = 1.0;
  spacing[2] = 1.0;

  for (int axis = 0; axis < 3; axis++)
  {
    int wholeMin = ext[axis*2];
    int wholeMax = ext[axis*2+1];
    int dimension = wholeMax - wholeMin + 1;

    // Scale the output extent
    wholeMin = static_cast<int>(  ceil( static_cast<double>
                                        ( wholeMin * this->Magnification )
                                      )
                               );
    wholeMax = ( dimension != 1 )
               ? wholeMin + static_cast<int>
                 (   floor(  static_cast<double>
                             ( dimension * this->Magnification )
                          )
                 ) -1
               : wholeMin;

    ext[ axis * 2     ] = wholeMin;
    ext[ axis * 2 + 1 ] = wholeMax;
  }

  vtkDebugMacro( << "request info whole ext = " << PRINTEXTENT( ext ) << endl );

  outInfo->Set( vtkStreamingDemandDrivenPipeline::WHOLE_EXTENT(), ext, 6 );
  outInfo->Set( vtkDataObject::SPACING(), spacing, 3 );

  return 1;
}

//----------------------------------------------------------------------------
int vtkStructuredGridLIC2D::RequestUpdateExtent (
  vtkInformation * vtkNotUsed(request),
  vtkInformationVector **inputVector,
  vtkInformationVector *outputVector)
{
  vtkInformation *inInfo = inputVector[0]->GetInformationObject(0);
  vtkInformation *outInfo = outputVector->GetInformationObject(1);


  // Tell the vector field input the extents that we need from it.
  // The downstream request needs to be downsized based on the Magnification.
  int ext[6];
  outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT(), ext);

  vtkDebugMacro( << "request update extent, update ext = "
                 << PRINTEXTENT( ext ) << endl );

  for (int axis = 0; axis < 3; axis++)
  {
    int wholeMin = ext[axis*2];
    int wholeMax = ext[axis*2+1];
    int dimension = wholeMax - wholeMin + 1;

    // Scale the output extent
    wholeMin = static_cast<int>(ceil(static_cast<double>(wholeMin / this->Magnification)));
    wholeMax = dimension != 1? wholeMin + static_cast<int>(floor(static_cast<double>(dimension / this->Magnification))) -1:

    ext[axis*2] = wholeMin;
    ext[axis*2+1] = wholeMax;
  }
  vtkDebugMacro( << "UPDATE_EXTENT: " << ext[0] << ", " << ext[1] << ", "
                 << ext[2] << ", "    << ext[3] << ", " << ext[4] << ", "
                 << ext[5] << endl );
  inInfo->Set(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT(), ext, 6);

  vtkDebugMacro( << "request update extent, update ext2 = "
                 << PRINTEXTENT( ext ) << endl );


  if(inputVector[1]!=0 && inputVector[1]->GetInformationObject(0) != nullptr) // optional input
  {
    inInfo = inputVector[1]->GetInformationObject(0);
    // always request the whole extent
    inInfo->Set(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT(),
                inInfo->Get(vtkStreamingDemandDrivenPipeline::WHOLE_EXTENT()),
                6);
  }

  return 1;
}

//----------------------------------------------------------------------------
// Stolen from vtkImageAlgorithm. Should be in vtkStructuredGridAlgorithm.
void vtkStructuredGridLIC2D::AllocateOutputData(vtkDataObject *output,
                                                vtkInformation *outInfo)
{
  // set the extent to be the update extent
  vtkStructuredGrid *out = vtkStructuredGrid::SafeDownCast(output);
  if (out)
  {
    out->SetExtent(outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT()));
  }
  else
  {
    vtkImageData *out2 = vtkImageData::SafeDownCast(output);
    if (out2)
    {
      out2->SetExtent(outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT()));
    }
  }
}

//----------------------------------------------------------------------------
// Stolen from vtkImageData. Should be in vtkStructuredGrid.
void vtkStructuredGridLIC2D::AllocateScalars(vtkStructuredGrid *sg,
                                             vtkInformation *outInfo)
{
  int newType = VTK_DOUBLE;
  int newNumComp = 1;

  vtkInformation *scalarInfo = vtkDataObject::GetActiveFieldInformation(
    outInfo,
    vtkDataObject::FIELD_ASSOCIATION_POINTS, vtkDataSetAttributes::SCALARS);
  if (scalarInfo)
  {
    newType = scalarInfo->Get( vtkDataObject::FIELD_ARRAY_TYPE() );
    if ( scalarInfo->Has(vtkDataObject::FIELD_NUMBER_OF_COMPONENTS()) )
    {
      newNumComp = scalarInfo->Get( vtkDataObject::FIELD_NUMBER_OF_COMPONENTS() );
    }
  }

  vtkDataArray *scalars;

  // if the scalar type has not been set then we have a problem
  if (newType == VTK_VOID)
  {
    vtkErrorMacro("Attempt to allocate scalars before scalar type was set!.");
    return;
  }

  const int* extent = sg->GetExtent();
  // Use vtkIdType to avoid overflow on large images
  vtkIdType dims[3];
  dims[0] = extent[1] - extent[0] + 1;
  dims[1] = extent[3] - extent[2] + 1;
  dims[2] = extent[5] - extent[4] + 1;
  vtkIdType imageSize = dims[0]*dims[1]*dims[2];

  // if we currently have scalars then just adjust the size
  scalars = sg->GetPointData()->GetScalars();
  if (scalars && scalars->GetDataType() == newType
      && scalars->GetReferenceCount() == 1)
  {
    scalars->SetNumberOfComponents(newNumComp);
    scalars->SetNumberOfTuples(imageSize);
    // Since the execute method will be modifying the scalars
    // directly.
    scalars->Modified();
    return;
  }

  // allocate the new scalars
  scalars = vtkDataArray::CreateDataArray(newType);
  scalars->SetNumberOfComponents(newNumComp);

  // allocate enough memory
  scalars->SetNumberOfTuples(imageSize);

  sg->GetPointData()->SetScalars(scalars);
  scalars->Delete();
}


//----------------------------------------------------------------------------
int vtkStructuredGridLIC2D::RequestData(
  vtkInformation        * vtkNotUsed(request),
  vtkInformationVector ** inputVector,
  vtkInformationVector  * outputVector )
{
  // 3 passes:
  // pass 1: render to compute the transformed vector field for the points.
  // pass 2: perform LIC with the new vector field. This has to happen in a
  // different pass than computation of the transformed vector.
  // pass 3: Render structured slice quads with correct texture correct
  // tcoords and apply the LIC texture to it.

  vtkInformation    * inInfo = inputVector[0]->GetInformationObject(0);
  vtkStructuredGrid * input  = vtkStructuredGrid::SafeDownCast
                   (  inInfo->Get( vtkDataObject::DATA_OBJECT() )  );

  int inputRequestedExtent[6];
  inInfo->Get(
        vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT(),
        inputRequestedExtent);

  // Check if the input image is a 2D image (not 0D, not 1D, not 3D)
  int dims[3];
  vtkStructuredExtent::GetDimensions( inputRequestedExtent, dims );

  vtkDebugMacro( << "dims = " << dims[0] << " "
                 << dims[1] << " " << dims[2] << endl );
  vtkDebugMacro( << "requested ext = " << inputRequestedExtent[0] << " "
                 << inputRequestedExtent[1] << " " << inputRequestedExtent[2]
                 << " " << inputRequestedExtent[3] << " "
                 << inputRequestedExtent[4] << " "
                 << inputRequestedExtent[5] << endl );

  if(   !( (dims[0] == 1) && (dims[1] > 1) && (dims[2] > 1) )
     && !( (dims[1] == 1) && (dims[0] > 1) && (dims[2] > 1) )
     && !( (dims[2] == 1) && (dims[0] > 1) && (dims[1] > 1) )
    )
  {
    vtkErrorMacro( << "input is not a 2D image." << endl );
    input  = nullptr;
    inInfo = nullptr;
    return 0;
  }
  if( input->GetPointData() == 0 )
  {
    vtkErrorMacro( << "input does not have point data." );
    input  = nullptr;
    inInfo = nullptr;
    return 0;
  }
  if( input->GetPointData()->GetVectors() == 0 )
  {
    vtkErrorMacro( << "input does not vectors on point data." );
    input  = nullptr;
    inInfo = nullptr;
    return 0;
  }

  if ( !this->Context )
  {
    vtkRenderWindow * renWin = vtkRenderWindow::New();
    if (  this->SetContext( renWin ) == 0  )
    {
      vtkErrorMacro("Invalid render window");
      renWin->Delete();
      renWin = nullptr;
      input  = nullptr;
      inInfo = nullptr;
      return 0;
    }

    renWin = nullptr; // to be released via this->context
    this->OwnWindow = true;
  }

  vtkInformation    * outInfo = outputVector->GetInformationObject(0);
  vtkStructuredGrid * output  = vtkStructuredGrid::SafeDownCast(
    outInfo->Get(vtkDataObject::DATA_OBJECT()));
  this->AllocateOutputData(output, outInfo);
  output->ShallowCopy(input);

  vtkInformation * outInfoTexture = outputVector->GetInformationObject(1);
  vtkImageData   * outputTexture  = vtkImageData::SafeDownCast(
    outInfoTexture->Get(vtkDataObject::DATA_OBJECT()));
  this->AllocateOutputData(outputTexture, outInfoTexture);

  // Noise.
  vtkInformation *noiseInfo = inputVector[1]->GetInformationObject(0);
  vtkImageData *noise = 0;
  if (noiseInfo == 0)
  {
    this->NoiseSource->Update();
    noise = this->NoiseSource->GetOutput();
  }
  else
  {
    noise = vtkImageData::SafeDownCast(
      noiseInfo->Get(vtkDataObject::DATA_OBJECT()));

    if(noise->GetPointData()==0)
    {
      vtkErrorMacro(<<"provided noise does not have point data.");
      return 0;
    }
    if(noise->GetPointData()->GetScalars()==0)
    {
      vtkErrorMacro(<<"provided noise does not have scalars on point data.");
      return 0;
    }
  }

  vtkOpenGLClearErrorMacro();

  int width;
  int height;
  int firstComponent;
  int secondComponent;
  int slice;
  if (dims[0] == 1)
  {
    vtkDebugMacro( << "x" << endl );
    firstComponent = 1;
    secondComponent = 2;
    slice = 0;
  }
  else
  {
    if (dims[1] == 1)
    {
      vtkDebugMacro( << "y" << endl );
      firstComponent = 0;
      secondComponent = 2;
      slice = 1;
    }
    else
    {
      vtkDebugMacro( << "z" << endl );
      firstComponent = 0;
      secondComponent = 1;
      slice = 2;
    }
  }

  width = dims[firstComponent];
  height = dims[secondComponent];

  vtkDebugMacro( << "w = " << width << " h = " << height << endl );

  vtkDataTransferHelper * vectorFieldBus = vtkDataTransferHelper::New();
  vectorFieldBus->SetContext(this->Context);
  vectorFieldBus->SetCPUExtent(inputRequestedExtent); // input->GetExtent());
  vectorFieldBus->SetGPUExtent(inputRequestedExtent); // input->GetExtent());
  //  vectorFieldBus->SetTextureExtent(input->GetExtent());
  vectorFieldBus->SetArray(input->GetPointData()->GetVectors());

  vtkDataTransferHelper * pointBus = vtkDataTransferHelper::New();
  pointBus->SetContext(this->Context);
  pointBus->SetCPUExtent(inputRequestedExtent); // input->GetExtent());
  pointBus->SetGPUExtent(inputRequestedExtent); // input->GetExtent());
  //  pointBus->SetTextureExtent(input->GetExtent());
  pointBus->SetArray(input->GetPoints()->GetData());

  vtkOpenGLExtensionManager * mgr = vtkOpenGLExtensionManager::New();
  mgr->SetRenderWindow(this->Context);

  // Vector field in image space.
  int magWidth = this->Magnification*width;
  int magHeight = this->Magnification*height;

  vtkTextureObject * vector2 = vtkTextureObject::New();
  vector2->SetContext(this->Context);
  vector2->Create2D(magWidth,magHeight,3,VTK_FLOAT,false);

  vtkDebugMacro( << "Vector field in image space (target) textureId = "
                 << vector2->GetHandle() << endl );

  vtkFrameBufferObject *fbo = vtkFrameBufferObject::New();
  fbo->SetContext(this->Context);
  fbo->SetColorBuffer(0,vector2);
  fbo->SetNumberOfRenderTargets(1);
  fbo->SetActiveBuffer(0);

  // TODO --
  // step size is incorrect here
  // guard pixels are needed for parallel operations

  if (  !fbo->Start( magWidth, magHeight, false )  )
  {
    mgr->Delete();
    fbo->Delete();
    vector2->Delete();
    pointBus->Delete();
    vectorFieldBus->Delete();

    mgr = nullptr;
    fbo = nullptr;
    vector2  = nullptr;
    pointBus = nullptr;
    vectorFieldBus   = nullptr;

    noise   = nullptr;
    input   = nullptr;
    inInfo  = nullptr;
    output  = nullptr;
    outInfo = nullptr;
    noiseInfo = nullptr;
    outputTexture  = nullptr;
    outInfoTexture = nullptr;

    this->FBOSuccess = 0;
    return 0;
  }
  this->FBOSuccess = 1;

  vtkShaderProgram2 *pgm = vtkShaderProgram2::New();
  pgm->SetContext(static_cast<vtkOpenGLRenderWindow *>(this->Context.GetPointer()));

  vtkShader2 *shader = vtkShader2::New();
  shader->SetType(VTK_SHADER_TYPE_FRAGMENT);
  shader->SetSourceCode(vtkStructuredGridLIC2D_fs);
  shader->SetContext(pgm->GetContext());
  pgm->GetShaders()->AddItem(shader);
  shader->Delete();
  shader = nullptr;

  pgm->Build();
  if(pgm->GetLastBuildStatus()!=VTK_SHADER_PROGRAM2_LINK_SUCCEEDED)
  {
    vtkErrorMacro("shader build error.");
    return 0;
  }

  int value = 0;
  pgm->GetUniformVariables()->SetUniformi("texPoints",1,&value);
  value = 1;
  pgm->GetUniformVariables()->SetUniformi("texVectorField",1,&value);
  float fvalues[3];
  fvalues[0] = static_cast<float>(dims[0]);
  fvalues[1] = static_cast<float>(dims[1]);
  fvalues[2] = static_cast<float>(dims[2]);
  pgm->GetUniformVariables()->SetUniformf("uDimensions",3,fvalues);
  value = slice;
  pgm->GetUniformVariables()->SetUniformi("uSlice",1,&slice);

  vtkgl::ActiveTexture(vtkgl::TEXTURE0);
  pointBus->Upload(0,0);
  vtkTextureObject *points = pointBus->GetTexture();
  points->Bind();
  glTexParameteri(points->GetTarget(),GL_TEXTURE_WRAP_S, GL_CLAMP);
  glTexParameteri(points->GetTarget(),GL_TEXTURE_WRAP_T, GL_CLAMP);
  glTexParameteri(points->GetTarget(), vtkgl::TEXTURE_WRAP_R, GL_CLAMP);
  glTexParameteri(points->GetTarget(), GL_TEXTURE_MIN_FILTER, GL_NEAREST);
  glTexParameteri(points->GetTarget(), GL_TEXTURE_MAG_FILTER, GL_NEAREST);

  vtkDebugMacro( << "points on texture unit 0, textureId == "
                 << points->GetHandle() << endl );

  vtkgl::ActiveTexture(vtkgl::TEXTURE1);
  vectorFieldBus->Upload(0,0);
  vtkTextureObject *vectorField = vectorFieldBus->GetTexture();
  vectorField->Bind();
  glTexParameteri(vectorField->GetTarget(),GL_TEXTURE_WRAP_S, GL_CLAMP);
  glTexParameteri(vectorField->GetTarget(),GL_TEXTURE_WRAP_T, GL_CLAMP);
  glTexParameteri(vectorField->GetTarget(), vtkgl::TEXTURE_WRAP_R, GL_CLAMP);
  glTexParameteri(vectorField->GetTarget(), GL_TEXTURE_MIN_FILTER, GL_NEAREST);
  glTexParameteri(vectorField->GetTarget(), GL_TEXTURE_MAG_FILTER, GL_NEAREST);

  vtkDebugMacro( << "vector field on texture unit 1, textureId == "
                 << vectorField->GetHandle() << endl );

  pgm->Use();
  if(!pgm->IsValid())
  {
    vtkErrorMacro(<<" validation of the program failed: "<<pgm->GetLastValidateLog());
  }
  vtkOpenGLCheckErrorMacro("failed during config");

  vtkDebugMacro( << "glFinish before rendering quad" << endl );

  fbo->RenderQuad(0, magWidth-1,0, magHeight-1);
  vtkOpenGLCheckErrorMacro("StructuredGridLIC2D projection fialed");

  vtkDebugMacro( << "glFinish after rendering quad" << endl );

  pgm->Restore();

  vtkLineIntegralConvolution2D *internal = vtkLineIntegralConvolution2D::New();
  if (  !internal->IsSupported( this->Context )  )
  {
    pgm->ReleaseGraphicsResources();

    pgm->Delete();
    mgr->Delete();
    fbo->Delete();
    vector2->Delete();
    internal->Delete();
    pointBus->Delete();
    vectorFieldBus->Delete();

    pgm = nullptr;
    mgr = nullptr;
    fbo = nullptr;
    vector2  = nullptr;
    internal = nullptr;
    pointBus = nullptr;
    vectorFieldBus = nullptr;

    noise   = nullptr;
    input   = nullptr;
    inInfo  = nullptr;
    points  = nullptr;
    output  = nullptr;
    outInfo = nullptr;
    noiseInfo   = nullptr;
    vectorField = nullptr;
    outputTexture  = nullptr;
    outInfoTexture = nullptr;

    this->LICSuccess = 0;
    return 0;
  }

  internal->SetContext(this->Context);
  internal->SetNumberOfSteps(this->Steps);
  internal->SetStepSize(this->StepSize);
  internal->SetComponentIds(firstComponent,secondComponent);

  vtkDataTransferHelper *noiseBus = vtkDataTransferHelper::New();
  noiseBus->SetContext(this->Context);
  noiseBus->SetCPUExtent(noise->GetExtent());
  noiseBus->SetGPUExtent(noise->GetExtent());
  //  noiseBus->SetTextureExtent(noise->GetExtent());
  noiseBus->SetArray(noise->GetPointData()->GetScalars());
  noiseBus->Upload(0,0);

  vtkTextureObject *licTex = internal->Execute(vector2, noiseBus->GetTexture());
  if (licTex == nullptr)
  {
    pgm->ReleaseGraphicsResources();

    pgm->Delete();
    mgr->Delete();
    fbo->Delete();
    vector2->Delete();
    internal->Delete();
    pointBus->Delete();
    noiseBus->Delete();
    vectorFieldBus->Delete();

    pgm = nullptr;
    mgr = nullptr;
    fbo = nullptr;
    vector2 = nullptr;
    internal = nullptr;
    pointBus = nullptr;
    noiseBus = nullptr;
    vectorFieldBus = nullptr;

    noise = nullptr;
    input = nullptr;
    inInfo = nullptr;
    points = nullptr;
    output = nullptr;
    outInfo = nullptr;
    noiseInfo = nullptr;
    vectorField = nullptr;
    outputTexture = nullptr;
    outInfoTexture = nullptr;

    this->LICSuccess = 0;
    return 0;
  }
  this->LICSuccess = 1;

  // transfer lic from texture to vtk array
  vtkPixelExtent magLicExtent(magWidth, magHeight);
  vtkIdType nOutTups = magLicExtent.Size();

  vtkFloatArray *licOut = vtkFloatArray::New();
  licOut->SetNumberOfComponents(3);
  licOut->SetNumberOfTuples(nOutTups);
  licOut->SetName("LIC");

  vtkPixelBufferObject *licPBO = licTex->Download();

  vtkPixelTransfer::Blit<float,float>(
        magLicExtent,
        magLicExtent,
        magLicExtent,
        magLicExtent,
        4,
        (float*)licPBO->MapPackedBuffer(),
        3,
        licOut->GetPointer(0));

  licPBO->UnmapPackedBuffer();
  licPBO->Delete();
  licTex->Delete();

  // mask and convert to gray scale 3 components
  float *pLicOut = licOut->GetPointer(0);
  for (vtkIdType i=0; i<nOutTups; ++i)
  {
    float lic = pLicOut[3*i];
    float mask = pLicOut[3*i+1];
    if ( mask != 0.0f )
    {
      pLicOut[3*i+1] = pLicOut[3*i+2] = pLicOut[3*i] = 0.0f;
    }
    else
    {
      pLicOut[3*i+1] = pLicOut[3*i+2] = lic;
    }
  }

  outputTexture->GetPointData()->SetScalars(licOut);
  licOut->Delete();

  // Pass three. Generate texture coordinates. Software.
  vtkFloatArray *tcoords = vtkFloatArray::New();
  tcoords->SetNumberOfComponents(2);
  tcoords->SetNumberOfTuples(dims[0]*dims[1]*dims[2]);
  output->GetPointData()->SetTCoords(tcoords);
  tcoords->Delete();

  double ddim[3];
  ddim[0] = static_cast<double>(dims[0]-1);
  ddim[1] = static_cast<double>(dims[1]-1);
  ddim[2] = static_cast<double>(dims[2]-1);

  int tz = 0;
  while(tz < dims[slice])
  {
    int ty = 0;
    while(ty < dims[secondComponent])
    {
      int tx = 0;
      while(tx < dims[firstComponent])
      {
        tcoords->SetTuple2(
              (tz*dims[secondComponent]+ty)*dims[firstComponent]+tx,
              tx/ddim[firstComponent],
              ty/ddim[secondComponent]);
        ++tx;
      }
      ++ty;
    }
    ++tz;
  }

  internal->Delete();
  noiseBus->Delete();
  vectorFieldBus->Delete();
  pointBus->Delete();
  mgr->Delete();
  vector2->Delete();
  fbo->Delete();
  pgm->ReleaseGraphicsResources();
  pgm->Delete();

  // Make sure the active texture is back to texture0 for the part of the
  // pipeline using OpenGL 1.1 (texture on actor)
  vtkgl::ActiveTexture(vtkgl::TEXTURE0);

  vtkOpenGLCheckErrorMacro("failed after RequestData");

  return 1;
}

//----------------------------------------------------------------------------
void vtkStructuredGridLIC2D::PrintSelf( ostream & os, vtkIndent indent )
{
  this->Superclass::PrintSelf( os, indent );

  os << indent << "Steps: " << this->Steps << "\n";
  os << indent << "StepSize: " << this->StepSize << "\n";
  os << indent << "FBOSuccess: " << this->FBOSuccess << "\n";
  os << indent << "LICSuccess: " << this->LICSuccess << "\n";
  os << indent << "Magnification: " << this->Magnification << "\n";
  os << indent << "OpenGLExtensionsSupported: "
               << this->OpenGLExtensionsSupported << "\n";
}
