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

  Program:   Visualization Toolkit
  Module:    vtkTriangularTexture.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 "vtkTriangularTexture.h"

#include "vtkImageData.h"
#include "vtkMath.h"
#include "vtkObjectFactory.h"
#include "vtkPointData.h"
#include "vtkUnsignedCharArray.h"

vtkCxxRevisionMacro(vtkTriangularTexture, "1.25");
vtkStandardNewMacro(vtkTriangularTexture);

// Instantiate object with XSize and YSize = 64; the texture pattern =1
// (opaque at centroid); and the scale factor set to 1.0.

vtkTriangularTexture::vtkTriangularTexture()
{
  this->XSize = this->YSize = 64;
  this->TexturePattern = 1;
  this->ScaleFactor = 1.0;
}

void vtkOpaqueAtElementCentroid (int XSize, int YSize, double ScaleFactor, 
                                 vtkUnsignedCharArray *newScalars)
{
  int i, j;
  double opacity;
  double point[3];
  double XScale = XSize + 1.0;
  double YScale = YSize + 1.0;
  unsigned char AGrayValue[2];
  double dist, distToV2, distToV3;
  double v1[3] = {0.0, 0.0, 0.0};
  double v2[3] = {1.0, 0.0, 0.0};
  double v3[3] = {0.5, sqrt(3.0)/2.0, 0.0};

  point[2] = 0.0;
  AGrayValue[0] = AGrayValue[1] = 255;

  for (j = 0; j < YSize; j++)
    {
    for (i = 0; i < XSize; i++) 
      {
      point[0] = i / XScale;
      point[1] = j / YScale;
      dist = vtkMath::Distance2BetweenPoints (point, v1);
      distToV2 = vtkMath::Distance2BetweenPoints (point, v2);
      if (distToV2 < dist)
        {
        dist = distToV2;
        }
      distToV3 = vtkMath::Distance2BetweenPoints (point, v3);
      if (distToV3 < dist)
        {
        dist = distToV3;
        }

      opacity = sqrt(dist) * ScaleFactor;
      if (opacity < .5)
        {
        opacity = 0.0;
        }
      if (opacity > .5)
        {
        opacity = 1.0;
        }
      AGrayValue[1] = (unsigned char) (opacity * 255);
      newScalars->SetValue ((XSize*j + i)*2, AGrayValue[0]);
      newScalars->SetValue ((XSize*j + i)*2 + 1, AGrayValue[1]);
      }         
    }
}

void vtkOpaqueAtVertices (int XSize, int YSize, double ScaleFactor, 
                          vtkUnsignedCharArray *newScalars)
{
  int i, j;
  double opacity;
  double point[3];
  double XScale = XSize + 1.0;
  double YScale = YSize + 1.0;
  unsigned char AGrayValue[2];
  double dist, distToV2, distToV3;
  double v1[3] = {0.0, 0.0, 0.0};
  double v2[3] = {1.0, 0.0, 0.0};
  double v3[3] = {0.5, sqrt(3.0)/2.0, 0.0};

  point[2] = 0.0;
  AGrayValue[0] = AGrayValue[1] = 255;

  for (j = 0; j < YSize; j++) 
    {
    for (i = 0; i < XSize; i++) 
      {
      point[0] = i / XScale;
      point[1] = j / YScale;
      dist = vtkMath::Distance2BetweenPoints (point, v1);
      distToV2 = vtkMath::Distance2BetweenPoints (point, v2);
      if (distToV2 < dist)
        {
        dist = distToV2;
        }
      distToV3 = vtkMath::Distance2BetweenPoints (point, v3);
      if (distToV3 < dist)
        {
        dist = distToV3;
        }

      opacity = sqrt(dist) * ScaleFactor;
      if (opacity < .5)
        {
        opacity = 0.0;
        }
      if (opacity > .5)
        {
        opacity = 1.0;
        }
      opacity = 1.0 - opacity;
      AGrayValue[1] = (unsigned char) (opacity * 255);
      newScalars->SetValue ((XSize*j + i)*2, AGrayValue[0]);
      newScalars->SetValue ((XSize*j + i)*2 + 1, AGrayValue[1]);
      }         
    }
}

//----------------------------------------------------------------------------
void vtkTriangularTexture::ExecuteInformation()
{
  vtkImageData *output = this->GetOutput();
  
  output->SetWholeExtent(0,this->XSize -1, 0, this->YSize - 1, 0,0);
  output->SetScalarType(VTK_UNSIGNED_CHAR);
  output->SetNumberOfScalarComponents(2);
}

void vtkTriangularTexture::ExecuteData(vtkDataObject *outp)
{
  vtkImageData *output = this->AllocateOutputData(outp);
  vtkUnsignedCharArray *newScalars = 
    vtkUnsignedCharArray::SafeDownCast(output->GetPointData()->GetScalars());
  
  if (this->XSize*this->YSize < 1)
    {
    vtkErrorMacro(<<"Bad texture (xsize,ysize) specification!");
    return;
    }

  switch (this->TexturePattern) 
    {
    case 1: // opaque at element vertices
      vtkOpaqueAtVertices (this->XSize, this->YSize, 
                           this->ScaleFactor, newScalars);
      break;

    case 2: // opaque at element centroid
      vtkOpaqueAtElementCentroid (this->XSize, this->YSize, 
                                  this->ScaleFactor, newScalars);
      break;

    case 3: // opaque in rings around vertices
      vtkErrorMacro(<<"Opaque vertex rings not implemented");
      break;
    }
}

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

  os << indent << "XSize:" << this->XSize << "\n";
  os << indent << "YSize:" << this->YSize << "\n";

  os << indent << "Texture Pattern:" << this->TexturePattern << "\n";

  os << indent << "Scale Factor:" << this->ScaleFactor << "\n";
}

