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

  Program:   Visualization Toolkit
  Module:    $RCSfile: vtkImageBlend.cxx,v $
  Language:  C++
  Date:      $Date: 2003/02/06 18:18:57 $
  Version:   $Revision: 1.30 $

  Copyright (c) 1993-2002 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 "vtkImageBlend.h"

#include "vtkImageData.h"
#include "vtkImageStencilData.h"
#include "vtkObjectFactory.h"
#include "vtkPointData.h"

vtkCxxRevisionMacro(vtkImageBlend, "$Revision: 1.30 $");
vtkStandardNewMacro(vtkImageBlend);
vtkCxxSetObjectMacro(vtkImageBlend,Stencil, vtkImageStencilData);

//----------------------------------------------------------------------------
vtkImageBlend::vtkImageBlend()
{
  this->Stencil = 0;
  this->Opacity = 0;
  this->OpacityArrayLength = 0;
  this->BlendMode = VTK_IMAGE_BLEND_MODE_NORMAL;
  this->CompoundThreshold = 0.0;
  this->DataWasPassed = 0;
}

//----------------------------------------------------------------------------
vtkImageBlend::~vtkImageBlend()
{
  this->SetStencil(0);
  if (this->Opacity)
    {
    delete [] this->Opacity;
    }
  this->OpacityArrayLength = 0;
}

//----------------------------------------------------------------------------
void vtkImageBlend::SetOpacity(int idx, double opacity)
{
  int i;
  int newLength;
  double *newArray;

  if (opacity < 0.0)
    {
    opacity = 0.0;
    }
  if (opacity > 1.0)
    {
    opacity = 1.0;
    }

  if (idx >= this->OpacityArrayLength)
    {
    newLength = idx + 1; 
    newArray = new double[newLength];
    for (i = 0; i < this->OpacityArrayLength; i++)
      {
      newArray[i] = this->Opacity[i];
      }
    for (; i < newLength; i++)
      {
      newArray[i] = 1.0;
      }
    if (this->Opacity)
      {
      delete [] this->Opacity;
      }
    this->Opacity = newArray;
    this->OpacityArrayLength = newLength;
    }

  if (this->Opacity[idx] != opacity)
    {
    this->Opacity[idx] = opacity;
    this->Modified();
    }
}
    
//----------------------------------------------------------------------------
double vtkImageBlend::GetOpacity(int idx)
{
  if (idx >= this->OpacityArrayLength)
    {
    return 1.0;
    }
  return this->Opacity[idx];
}    

//----------------------------------------------------------------------------
void vtkImageBlend::ExecuteInformation(vtkImageData **inDatas,
                                       vtkImageData *vtkNotUsed(outData))
{
  vtkImageStencilData *stencil = this->GetStencil();
  if (stencil)
    {
    stencil->SetSpacing(inDatas[0]->GetSpacing());
    stencil->SetOrigin(inDatas[0]->GetOrigin());
    }
}

//----------------------------------------------------------------------------
// This method computes the extent of the input region necessary to generate
// an output region.  Before this method is called "region" should have the
// extent of the output region.  After this method finishes, "region" should
// have the extent of the required input region.  The default method assumes
// the required input extent are the same as the output extent.
// Note: The splitting methods call this method with outRegion = inRegion.
void vtkImageBlend::ComputeInputUpdateExtent(int inExt[6],
                                             int outExt[6],
                                             int whichInput)
{
  memcpy(inExt,outExt,sizeof(int)*6);

  int *wholeExtent = this->GetInput(whichInput)->GetWholeExtent();
  int i;

  // clip with the whole extent
  for (i = 0; i < 3; i++)
    {
    if (inExt[2*i] < wholeExtent[2*i])
      {
      inExt[2*i] = wholeExtent[2*i];
      }
    if (inExt[2*i+1] > wholeExtent[2*i+1])
      {
      inExt[2*i+1] = wholeExtent[2*i+1];
      }
    }
}

//----------------------------------------------------------------------------
// This method checks to see if we can simply reference the input data
void vtkImageBlend::ExecuteData(vtkDataObject *output)
{
  // check to see if we have more than one input
  int singleInput = 1;
  for (int idx = 1; idx < this->NumberOfInputs; idx++)
    {
    if (this->GetInput(idx) != NULL)
      {
      singleInput = 0;
      }
    }
  if (singleInput)
    {
    vtkDebugMacro("ExecuteData: single input, passing data");

    vtkImageData *outData = (vtkImageData *)(output);
    vtkImageData *inData = this->GetInput();
 
    outData->SetExtent(inData->GetExtent());
    outData->GetPointData()->PassData(inData->GetPointData());
    this->DataWasPassed = 1;
    }
  else // multiple inputs
    {
    if (this->DataWasPassed)
      {
      ((vtkImageData *)output)->GetPointData()->SetScalars(NULL);
      this->DataWasPassed = 0;
      }
    
    vtkImageStencilData *stencil = this->GetStencil();
    if (stencil)
      {
      stencil->SetUpdateExtent(((vtkImageData *)output)->GetUpdateExtent());
      stencil->Update();
      }
    this->vtkImageMultipleInputFilter::ExecuteData(output);
    }
}

//----------------------------------------------------------------------------
// helper function for the stencil
template <class T>
inline int vtkBlendGetNextExtent(vtkImageStencilData *stencil,
                                 int &r1, int &r2, int rmin, int rmax,
                                 int yIdx, int zIdx, 
                                 T *&outPtr, T *&inPtr, 
                                 int outScalars, int inScalars,
                                 int &iter)
{
  // trivial case if stencil is not set
  if (!stencil)
    {
    if (iter++ == 0)
      {
      r1 = rmin;
      r2 = rmax;
      return 1;
      }
    return 0;
    }

  // save r2
  int oldr2 = r2;
  if (iter == 0)
    { // if no 'last time', start just before rmin
    oldr2 = rmin - 1;
    }

  int rval = stencil->GetNextExtent(r1, r2, rmin, rmax, yIdx, zIdx, iter);
  int incr = r1 - oldr2 - 1;
  if (rval == 0)
    {
    incr = rmax - oldr2;
    }

  outPtr += incr*outScalars;
  inPtr += incr*inScalars;

  return rval;
}

//----------------------------------------------------------------------------
// This templated function executes the filter for any type of data.
template <class T>
void vtkImageBlendExecute(vtkImageBlend *self, int extent[6], 
                          vtkImageData *inData, T *inPtr,
                          vtkImageData *outData, T *outPtr,
                          float opacity, int id)
{
  int idxX, idxY, idxZ;
  int minX = 0;
  int maxX = 0;
  int iter;
  int inIncX, inIncY, inIncZ;
  int outIncX, outIncY, outIncZ;
  int inC, outC;
  float minA,maxA;
  float r,f;
  unsigned long count = 0;
  unsigned long target;

  vtkImageStencilData *stencil = self->GetStencil();

  if (inData->GetScalarType() == VTK_DOUBLE ||
      inData->GetScalarType() == VTK_FLOAT)
    {
    minA = 0.0;
    maxA = 1.0;
    }
  else
    {
    minA = inData->GetScalarTypeMin();
    maxA = inData->GetScalarTypeMax();
    }

  r = opacity;
  f = 1.0-r;

  opacity = opacity/(maxA-minA);

  inC = inData->GetNumberOfScalarComponents();
  outC = outData->GetNumberOfScalarComponents();

  target = (unsigned long)((extent[3] - extent[2] + 1)*
                           (extent[5] - extent[4] + 1)/50.0);
  target++;
  
  // Get increments to march through data 
  inData->GetContinuousIncrements(extent, inIncX, inIncY, inIncZ);
  outData->GetContinuousIncrements(extent, outIncX, outIncY, outIncZ);

  // Loop through output pixels
  for (idxZ = extent[4]; idxZ <= extent[5]; idxZ++)
    {
    for (idxY = extent[2]; !self->AbortExecute && idxY <= extent[3]; idxY++)
      {
      if (!id) 
        {
        if (!(count%target))
          {
          self->UpdateProgress(count/(50.0*target));
          }
        count++;
        }

      iter = 0;
      if (outC >= 3 && inC >= 4)
        { // RGB(A) blended with RGBA
        while (vtkBlendGetNextExtent(stencil, minX, maxX, extent[0], extent[1],
                                     idxY, idxZ,
                                     outPtr, inPtr, outC, inC, iter))
          {
          for (idxX = minX; idxX <= maxX; idxX++)
            {
            r = opacity*(inPtr[3]-minA);
            f = 1.0-r;
            outPtr[0] = T(outPtr[0]*f + inPtr[0]*r);
            outPtr[1] = T(outPtr[1]*f + inPtr[1]*r);
            outPtr[2] = T(outPtr[2]*f + inPtr[2]*r);
            outPtr += outC; 
            inPtr += inC;
            }
          }
        }
      else if (outC >= 3 && inC == 3)
        { // RGB(A) blended with RGB
        while (vtkBlendGetNextExtent(stencil, minX, maxX, extent[0], extent[1],
                                     idxY, idxZ,
                                     outPtr, inPtr, outC, inC, iter))
          {
          for (idxX = minX; idxX <= maxX; idxX++)
            {
            outPtr[0] = T(outPtr[0]*f + inPtr[0]*r);
            outPtr[1] = T(outPtr[1]*f + inPtr[1]*r);
            outPtr[2] = T(outPtr[2]*f + inPtr[2]*r);
            outPtr += outC; 
            inPtr += inC;
            }
          }
        }
      else if (outC >= 3 && inC == 2)
        { // RGB(A) blended with luminance+alpha
        while (vtkBlendGetNextExtent(stencil, minX, maxX, extent[0], extent[1],
                                     idxY, idxZ,
                                     outPtr, inPtr, outC, inC, iter))
          {
          for (idxX = minX; idxX <= maxX; idxX++)
            {
            r = opacity*(inPtr[1]-minA);
            f = 1.0-r;
            outPtr[0] = T(outPtr[0]*f + (*inPtr)*r);
            outPtr[1] = T(outPtr[1]*f + (*inPtr)*r);
            outPtr[2] = T(outPtr[2]*f + (*inPtr)*r);
            outPtr += outC; 
            inPtr += 2;
            }
          }
        }
      else if (outC >= 3 && inC == 1)
        { // RGB(A) blended with luminance
        while (vtkBlendGetNextExtent(stencil, minX, maxX, extent[0], extent[1],
                                     idxY, idxZ,
                                     outPtr, inPtr, outC, inC, iter))
          {
          for (idxX = minX; idxX <= maxX; idxX++)
            {
            outPtr[0] = T(outPtr[0]*f + (*inPtr)*r);
            outPtr[1] = T(outPtr[1]*f + (*inPtr)*r);
            outPtr[2] = T(outPtr[2]*f + (*inPtr)*r);
            outPtr += outC; 
            inPtr++;
            }
          }
        }
      else if (inC == 2)
        { // luminance(+alpha) blended with luminance+alpha
        while (vtkBlendGetNextExtent(stencil, minX, maxX, extent[0], extent[1],
                                     idxY, idxZ,
                                     outPtr, inPtr, outC, inC, iter))
          {
          for (idxX = minX; idxX <= maxX; idxX++)
            {
            r = opacity*(inPtr[1]-minA);
            f = 1.0-r;
            *outPtr = T((*outPtr)*f + (*inPtr)*r);
            outPtr += outC; 
            inPtr += 2;
            }
          }
        }
      else
        { // luminance(+alpha) blended with luminance
        while (vtkBlendGetNextExtent(stencil, minX, maxX, extent[0], extent[1],
                                     idxY, idxZ,
                                     outPtr, inPtr, outC, inC, iter))
          {
          for (idxX = minX; idxX <= maxX; idxX++)
            {
            *outPtr = T((*outPtr)*f + (*inPtr)*r);
            outPtr += outC; 
            inPtr++;
            }
          }
        }
      outPtr += outIncY;
      inPtr += inIncY;
      }
    outPtr += outIncZ;
    inPtr += inIncZ;
    }
}

//----------------------------------------------------------------------------
// This templated function executes the filter specifically for char data
template <class T>
void vtkImageBlendExecuteChar(vtkImageBlend *self, int extent[6], 
                              vtkImageData *inData, T *inPtr,
                              vtkImageData *outData, T *outPtr,
                              float opacity, int id)
{
  int idxX, idxY, idxZ;
  int minX = 0;
  int maxX = 0;
  int iter;
  int inIncX, inIncY, inIncZ;
  int outIncX, outIncY, outIncZ;
  int inC, outC;
  unsigned short r,f;
  unsigned long count = 0;
  unsigned long target;

  vtkImageStencilData *stencil = self->GetStencil();

  r = (unsigned short)(255*opacity);
  f = 255-r;

  inC = inData->GetNumberOfScalarComponents();
  outC = outData->GetNumberOfScalarComponents();

  target = (unsigned long)((extent[3] - extent[2] + 1)*
                           (extent[5] - extent[4] + 1)/50.0);
  target++;  

  // Get increments to march through data 
  inData->GetContinuousIncrements(extent, inIncX, inIncY, inIncZ);
  outData->GetContinuousIncrements(extent, outIncX, outIncY, outIncZ);

   // Loop through ouput pixels
  for (idxZ = extent[4]; idxZ <= extent[5]; idxZ++)
    {
    for (idxY = extent[2]; !self->AbortExecute && idxY <= extent[3]; idxY++)
      {
      if (!id) 
        {
        if (!(count%target))
          {
          self->UpdateProgress(count/(50.0*target));
          }
        count++;
        }
      
      iter = 0;
      if (outC >= 3 && inC >= 4)
        { // RGB(A) blended with RGBA
        while (vtkBlendGetNextExtent(stencil, minX, maxX, extent[0], extent[1],
                                     idxY, idxZ,
                                     outPtr, inPtr, outC, inC, iter))
          {
          for (idxX = minX; idxX <= maxX; idxX++)
            {
            r = (unsigned short)(inPtr[3]*opacity);
            f = 255-r;
            outPtr[0] = (outPtr[0]*f + inPtr[0]*r) >> 8;
            outPtr[1] = (outPtr[1]*f + inPtr[1]*r) >> 8;
            outPtr[2] = (outPtr[2]*f + inPtr[2]*r) >> 8;
            outPtr += outC; 
            inPtr += inC;
            }
          }
        }
      else if (outC >= 3 && inC == 3)
        { // RGB(A) blended with RGB
        while (vtkBlendGetNextExtent(stencil, minX, maxX, extent[0], extent[1],
                                     idxY, idxZ,
                                     outPtr, inPtr, outC, inC, iter))
          {
          for (idxX = minX; idxX <= maxX; idxX++)
            {
            outPtr[0] = (outPtr[0]*f + inPtr[0]*r) >> 8;
            outPtr[1] = (outPtr[1]*f + inPtr[1]*r) >> 8;
            outPtr[2] = (outPtr[2]*f + inPtr[2]*r) >> 8;
            outPtr += outC; 
            inPtr += inC;
            }
          }
        }
      else if (outC >= 3 && inC == 2)
        { // RGB(A) blended with luminance+alpha
        while (vtkBlendGetNextExtent(stencil, minX, maxX, extent[0], extent[1],
                                     idxY, idxZ,
                                     outPtr, inPtr, outC, inC, iter))
          {
          for (idxX = minX; idxX <= maxX; idxX++)
            {
            r = (unsigned short)(inPtr[1]*opacity);
            f = 255-r;
            outPtr[0] = (outPtr[0]*f + (*inPtr)*r) >> 8;
            outPtr[1] = (outPtr[1]*f + (*inPtr)*r) >> 8;
            outPtr[2] = (outPtr[2]*f + (*inPtr)*r) >> 8;
            outPtr += outC; 
            inPtr += 2;
            }
          }
        }
      else if (outC >= 3 && inC == 1)
        { // RGB(A) blended with luminance
        while (vtkBlendGetNextExtent(stencil, minX, maxX, extent[0], extent[1],
                                     idxY, idxZ,
                                     outPtr, inPtr, outC, inC, iter))
          {
          for (idxX = minX; idxX <= maxX; idxX++)
            {
            outPtr[0] = (outPtr[0]*f + (*inPtr)*r) >> 8;
            outPtr[1] = (outPtr[1]*f + (*inPtr)*r) >> 8;
            outPtr[2] = (outPtr[2]*f + (*inPtr)*r) >> 8;
            outPtr += outC; 
            inPtr++;
            }
          }
        }
      else if (inC == 2)
        { // luminance(+alpha) blended with luminance+alpha
        while (vtkBlendGetNextExtent(stencil, minX, maxX, extent[0], extent[1],
                                     idxY, idxZ,
                                     outPtr, inPtr, outC, inC, iter))
          {
          for (idxX = minX; idxX <= maxX; idxX++)
            {
            r = (unsigned short)(inPtr[1]*opacity);
            f = 255-r;
            *outPtr = ((*outPtr)*f + (*inPtr)*r) >> 8;
            outPtr += outC; 
            inPtr += 2;
            }
          }
        }
      else
        { // luminance(+alpha) blended with luminance
        while (vtkBlendGetNextExtent(stencil, minX, maxX, extent[0], extent[1],
                                     idxY, idxZ,
                                     outPtr, inPtr, outC, inC, iter))
          {
          for (idxX = minX; idxX <= maxX; idxX++)
            {
            *outPtr = ((*outPtr)*f + (*inPtr)*r) >> 8;
            outPtr += outC; 
            inPtr++;
            }
          }
        }
      outPtr += outIncY;
      inPtr += inIncY;
      }
    outPtr += outIncZ;
    inPtr += inIncZ;
    }
}


//----------------------------------------------------------------------------
// This function simply does a copy (for the first input)
//----------------------------------------------------------------------------
void vtkImageBlendCopyData(vtkImageData *inData, vtkImageData *outData,
                           int *ext)
{
  int idxY, idxZ, maxY, maxZ;
  int inIncX, inIncY, inIncZ, rowLength;
  unsigned char *inPtr, *inPtr1, *outPtr;
 
  inPtr = (unsigned char *) inData->GetScalarPointerForExtent(ext);
  outPtr = (unsigned char *) outData->GetScalarPointerForExtent(ext);
 
  // Get increments to march through inData
  inData->GetIncrements(inIncX, inIncY, inIncZ);
 
  // find the region to loop over
  rowLength = (ext[1] - ext[0]+1)*inIncX*inData->GetScalarSize();
  maxY = ext[3] - ext[2];
  maxZ = ext[5] - ext[4];

  inIncY *= inData->GetScalarSize();
  inIncZ *= inData->GetScalarSize();

  // Loop through outData pixels
  for (idxZ = 0; idxZ <= maxZ; idxZ++)
    {
    inPtr1 = inPtr + idxZ*inIncZ;
    for (idxY = 0; idxY <= maxY; idxY++)
      {
      memcpy(outPtr,inPtr1,rowLength);
      inPtr1 += inIncY;
      outPtr += rowLength;
      }
    }
}


//----------------------------------------------------------------------------
// This templated function executes the filter for any type of data.
template <class T>
void vtkImageBlendCompoundExecute(vtkImageBlend *self,
                                  int extent[6], 
                                  vtkImageData *inData, 
                                  T *inPtr,
                                  vtkImageData *tmpData, 
                                  float opacity,
                                  float threshold)
{
  unsigned long count = 0;
  unsigned long target;

  target = (unsigned long)((extent[3] - extent[2] + 1)*
                           (extent[5] - extent[4] + 1)/50.0);
  target++;
  
  // Get increments to march through data 

  int inIncX, inIncY, inIncZ;
  int inC;

  inData->GetContinuousIncrements(extent, inIncX, inIncY, inIncZ);
  inC = inData->GetNumberOfScalarComponents();

  int tmpIncX, tmpIncY, tmpIncZ;
  int tmpC;

  tmpData->GetContinuousIncrements(extent, tmpIncX, tmpIncY, tmpIncZ);
  tmpC = tmpData->GetNumberOfScalarComponents();

  float* tmpPtr = (float *)tmpData->GetScalarPointerForExtent(extent);  

  // Opacity

  float minA, maxA;
  float r;

  if (inData->GetScalarType() == VTK_DOUBLE ||
      inData->GetScalarType() == VTK_FLOAT)
    {
    minA = 0.0;
    maxA = 1.0;
    }
  else
    {
    minA = (float)inData->GetScalarTypeMin();
    maxA = (float)inData->GetScalarTypeMax();
    }

  r = opacity;
  opacity = opacity/(maxA-minA);

  if ((inC == 3 || inC == 1) && r <= threshold)
    {
    return;
    }

  // Loop through output pixels

  for (int idxZ = extent[4]; idxZ <= extent[5]; idxZ++)
    {
    for (int idxY = extent[2]; !self->AbortExecute && idxY<=extent[3]; idxY++)
      {
      if (!(count%target))
        {
        self->UpdateProgress(count/(50.0*target));
        }
      count++;
      
      if (tmpC >= 3)
        {

        // RGB(A) blended with RGBA
        if (inC >= 4)
          { 
          for (int idxX = extent[0]; idxX <= extent[1]; idxX++)
            {
            r = opacity * ((float)inPtr[3] - minA);
            if (r > threshold) 
              {
              tmpPtr[0] += (float)inPtr[0] * r;
              tmpPtr[1] += (float)inPtr[1] * r;
              tmpPtr[2] += (float)inPtr[2] * r;
              tmpPtr[3] += r;
              }
            tmpPtr += 4; 
            inPtr += inC;
            }
          }

        // RGB(A) blended with RGB
        else if (inC == 3)
          { 
          for (int idxX = extent[0]; idxX <= extent[1]; idxX++)
            {
            tmpPtr[0] += (float)inPtr[0] * r;
            tmpPtr[1] += (float)inPtr[1] * r;
            tmpPtr[2] += (float)inPtr[2] * r;
            tmpPtr[3] += r;
            tmpPtr += 4; 
            inPtr += inC;
            }
          }

        // RGB(A) blended with luminance+alpha
        else if (inC == 2)
          { 
          for (int idxX = extent[0]; idxX <= extent[1]; idxX++)
            {
            r = opacity * ((float)inPtr[1] - minA);
            if (r > threshold) 
              {
              tmpPtr[0] += (float)(*inPtr) * r;
              tmpPtr[1] += (float)(*inPtr) * r;
              tmpPtr[2] += (float)(*inPtr) * r;
              tmpPtr[3] += r;
              }
            tmpPtr += 4; 
            inPtr += 2;
            }
          }

        // RGB(A) blended with luminance
        else if (inC == 1)
          { 
          for (int idxX = extent[0]; idxX <= extent[1]; idxX++)
            {
            tmpPtr[0] += (float)(*inPtr) * r;
            tmpPtr[1] += (float)(*inPtr) * r;
            tmpPtr[2] += (float)(*inPtr) * r;
            tmpPtr[3] += r;
            tmpPtr += 4; 
            inPtr++;
            }
          }
        }

      // luminance(+alpha) blended with luminance+alpha
      else if (inC == 2)
        { 
        for (int idxX = extent[0]; idxX <= extent[1]; idxX++)
          {
          r = opacity * ((float)inPtr[1] - minA);
          if (r > threshold) 
            {
            tmpPtr[0] = (float)(*inPtr) * r;
            tmpPtr[1] += r;
            }
          tmpPtr += 2; 
          inPtr += 2;
          }
        }

      // luminance(+alpha) blended with luminance
      else
        { 
        for (int idxX = extent[0]; idxX <= extent[1]; idxX++)
          {
          tmpPtr[0] = (float)(*inPtr) * r;
          tmpPtr[1] += r;
          tmpPtr += 2; 
          inPtr++;
          }
        }

      tmpPtr += tmpIncY;
      inPtr += inIncY;
      }
    tmpPtr += tmpIncZ;
    inPtr += inIncZ;
    }
}


//----------------------------------------------------------------------------
// This templated function executes the filter for any type of data.
template <class T>
void vtkImageBlendCompoundTransferExecute(vtkImageBlend *self,
                                          int extent[6], 
                                          vtkImageData *outData, 
                                          T *outPtr,
                                          vtkImageData *tmpData)
{
  // Get increments to march through data 

  int outIncX, outIncY, outIncZ;
  int outC;

  outData->GetContinuousIncrements(extent, outIncX, outIncY, outIncZ);
  outC = outData->GetNumberOfScalarComponents();

  int tmpIncX, tmpIncY, tmpIncZ;
  int tmpC;

  tmpData->GetContinuousIncrements(extent, tmpIncX, tmpIncY, tmpIncZ);
  tmpC = tmpData->GetNumberOfScalarComponents();

  float* tmpPtr = (float *)tmpData->GetScalarPointerForExtent(extent);  

  // Loop through output pixels

  for (int idxZ = extent[4]; idxZ <= extent[5]; idxZ++)
    {
    for (int idxY = extent[2]; !self->AbortExecute && idxY<=extent[3]; idxY++)
      {
      if (tmpC >= 3)
        {
        for (int idxX = extent[0]; idxX <= extent[1]; idxX++)
          {
          if (tmpPtr[3] != 0) 
            {
            outPtr[0] = T(tmpPtr[0] / tmpPtr[3]);
            outPtr[1] = T(tmpPtr[1] / tmpPtr[3]);
            outPtr[2] = T(tmpPtr[2] / tmpPtr[3]);
            } 
          else 
            {
            outPtr[0] = outPtr[1] = outPtr[2] = T(0);
            }
          tmpPtr += 4; 
          outPtr += outC;
          }
        }
      else 
        {
        for (int idxX = extent[0]; idxX <= extent[1]; idxX++)
          {
          if (tmpPtr[1] != 0) 
            {
            *outPtr = T(tmpPtr[0] / tmpPtr[1]);
            }
          else
            {
            *outPtr = T(0);
            }
          tmpPtr += 2;
          outPtr += outC;
          }
        }

      tmpPtr += tmpIncY;
      outPtr += outIncY;
      }
    tmpPtr += tmpIncZ;
    outPtr += outIncZ;
    }
}


//----------------------------------------------------------------------------
// This method is passed a input and output regions, and executes the filter
// algorithm to fill the output from the inputs.
// It just executes a switch statement to call the correct function for
// the regions data types.
void vtkImageBlend::ThreadedExecute(vtkImageData **inData, 
                                    vtkImageData *outData,
                                    int outExt[6], 
                                    int id)
{
  int extent[6];
  void *inPtr;
  void *outPtr;

  float opacity;

  vtkImageData *tmpData = NULL;
  
  // check

  if (inData[0]->GetNumberOfScalarComponents() > 4)
    {
    vtkErrorMacro("The first input can have a maximum of four components");
    return;
    }

  // init

  switch (this->BlendMode)
    {
    case VTK_IMAGE_BLEND_MODE_NORMAL:
      // copy the first image directly to the output
      vtkDebugMacro("Execute: copy input 0 to the output.");
      vtkImageBlendCopyData(inData[0], outData, outExt);
      break;

    case VTK_IMAGE_BLEND_MODE_COMPOUND:
      tmpData = vtkImageData::New();
      if (tmpData == NULL) 
        {
        vtkErrorMacro(<< "Execute: Unable to allocate memory");
        return;
        }
      tmpData->SetExtent(outExt);
      tmpData->SetNumberOfScalarComponents(
        (outData->GetNumberOfScalarComponents() >= 3 ? 3 : 1) + 1);
      tmpData->SetScalarType(VTK_FLOAT);
      tmpData->AllocateScalars();
      memset((void *)tmpData->GetScalarPointer(), 0, 
             (outExt[1] - outExt[0] + 1) * 
             (outExt[3] - outExt[2] + 1) * 
             (outExt[5] - outExt[4] + 1) *
             tmpData->GetNumberOfScalarComponents() * 
             tmpData->GetScalarSize());
      break;

    default:
      vtkErrorMacro(<< "Execute: Unknown blending mode");
    }

  // process each input

  int first_index = (this->BlendMode == VTK_IMAGE_BLEND_MODE_NORMAL ? 1 : 0);
  for (int idx1 = first_index; idx1 < this->NumberOfInputs; ++idx1)
    {
    if (inData[idx1] != NULL)
      {

      // RGB with RGB, greyscale with greyscale

      if ((inData[idx1]->GetNumberOfScalarComponents()+1)/2 == 2 &&
          (inData[0]->GetNumberOfScalarComponents()+1)/2 == 1)
        {
        vtkErrorMacro("input has too many components, can't blend RGB data \
                       into greyscale data");
        continue;
        }
      
      // this filter expects that input is the same type as output.
      
      if (inData[idx1]->GetScalarType() != outData->GetScalarType())
        {
        vtkErrorMacro(<< "Execute: input" << idx1 << " ScalarType (" << 
        inData[idx1]->GetScalarType() << 
        "), must match output ScalarType (" << outData->GetScalarType() 
        << ")");
        continue;
        }
      
      // input extents

      this->ComputeInputUpdateExtent(extent, outExt, idx1);

      int skip = 0;
      for (int i = 0; i < 3; i++)
        {
        if (outExt[2*i+1] < extent[2*i] || outExt[2*i] > extent[2*i+1])
          {
          // extents don't overlap, skip this input
          skip = 1; 
          }
        }
      
      if (skip) 
        {
        vtkDebugMacro("Execute: skipping input.");
        continue;
        }
      
      opacity = this->GetOpacity(idx1);
          
      inPtr = inData[idx1]->GetScalarPointerForExtent(extent);

      // vtkDebugMacro("Execute: " << idx1 << "=>" << extent[0] << ", " << extent[1] << " / " << extent[2] << ", " << extent[3] << " / " << extent[4] << ", " << extent[5]);
      
      switch (this->BlendMode)
        {
        case VTK_IMAGE_BLEND_MODE_NORMAL:
          outPtr = outData->GetScalarPointerForExtent(extent);  
          // for performance reasons, use a special method for unsigned char
          if (inData[idx1]->GetScalarType() == VTK_UNSIGNED_CHAR)
            {
            vtkImageBlendExecuteChar(this, extent,
                                     inData[idx1], (unsigned char *)(inPtr),
                                     outData, (unsigned char *)(outPtr),
                                     opacity, id);
            }
          else
            {
            switch (inData[idx1]->GetScalarType())
              {
              vtkTemplateMacro8(vtkImageBlendExecute, 
                                this, extent,
                                inData[idx1], (VTK_TT *)(inPtr),
                                outData, (VTK_TT *)(outPtr), 
                                opacity, id);
              default:
                vtkErrorMacro(<< "Execute: Unknown ScalarType");
                return;
              }
            }
          break;

        case VTK_IMAGE_BLEND_MODE_COMPOUND:
          switch (inData[idx1]->GetScalarType())
            {
            vtkTemplateMacro7(vtkImageBlendCompoundExecute, 
                              this, 
                              extent,
                              inData[idx1], 
                              (VTK_TT *)(inPtr), 
                              tmpData, 
                              opacity,
                              this->CompoundThreshold);
            default:
              vtkErrorMacro(<< "Execute: Unknown ScalarType");
              return;
            }
          break;

        default:
          vtkErrorMacro(<< "Execute: Unknown blending mode");
        }
      }
    }

  // conclude
  
  switch (this->BlendMode)
    {
    case VTK_IMAGE_BLEND_MODE_NORMAL:
      break;

    case VTK_IMAGE_BLEND_MODE_COMPOUND:
      outPtr = outData->GetScalarPointerForExtent(outExt);
      switch (outData->GetScalarType())
        {
        vtkTemplateMacro5(vtkImageBlendCompoundTransferExecute, 
                          this, 
                          outExt,
                          outData, 
                          (VTK_TT *)(outPtr), 
                          tmpData);
        default:
          vtkErrorMacro(<< "Execute: Unknown ScalarType");
          return;
        }
      tmpData->Delete();
      break;

    default:
      vtkErrorMacro(<< "Execute: Unknown blending mode");
    }
}


//----------------------------------------------------------------------------
void vtkImageBlend::PrintSelf(ostream& os, vtkIndent indent)
{
  this->Superclass::PrintSelf(os, indent);
  int i;
  for (i = 0; i < this->GetNumberOfInputs(); i++)
    {
    os << indent << "Opacity(" << i << "): " << this->GetOpacity(i) << endl; 
    }
  os << indent << "Stencil: " << this->GetStencil() << endl;
  os << indent << "Blend Mode: " << this->GetBlendModeAsString() << endl
     << indent << "Compound threshold: " << this->CompoundThreshold << endl;
}

