Method InternalUpdate

Rendering/VolumeOpenGL2/vtkOpenGLVolumeOpacityTable.cxx:15–65

Update opacity transfer function texture. ------------------------------------------------------------------------------

// Update opacity transfer function texture.
//------------------------------------------------------------------------------
void vtkOpenGLVolumeOpacityTable::InternalUpdate(
  vtkObject* func, int blendMode, double sampleDistance, double unitDistance, int filterValue)
{
  vtkPiecewiseFunction* scalarOpacity = vtkPiecewiseFunction::SafeDownCast(func);
  if (!scalarOpacity)
  {
    return;
  }

  scalarOpacity->GetTable(this->LastRange[0], this->LastRange[1], this->TextureWidth, this->Table);

  // Correct the opacity array for the spacing between the planes if we
  // are using a composite blending operation
  // TODO Fix this code for sample distance in three dimensions
  if (this->LastBlendMode == vtkVolumeMapper::COMPOSITE_BLEND)
  {
    float* ptr = this->Table;
    double factor = sampleDistance / unitDistance;
    int i = 0;
    while (i < this->TextureWidth)
    {
      if (*ptr > 0.0001f)
      {
        *ptr = static_cast<float>(1.0 - pow(1.0 - static_cast<double>(*ptr), factor));
      }
      ++ptr;
      ++i;
    }
  }
  else if (blendMode == vtkVolumeMapper::ADDITIVE_BLEND)
  {
    float* ptr = this->Table;
    double factor = sampleDistance / unitDistance;
    int i = 0;
    while (i < this->TextureWidth)
    {
      if (*ptr > 0.0001f)
      {
        *ptr = static_cast<float>(static_cast<double>(*ptr) * factor);
      }
      ++ptr;
      ++i;
    }
  }

  this->TextureObject->SetWrapS(vtkTextureObject::ClampToEdge);
  this->TextureObject->SetMagnificationFilter(filterValue);
  this->TextureObject->SetMinificationFilter(filterValue);
  this->TextureObject->Create2DFromRaw(
    this->TextureWidth, 1, this->NumberOfColorComponents, VTK_FLOAT, this->Table);
}

//------------------------------------------------------------------------------
bool vtkOpenGLVolumeOpacityTable::NeedsUpdate(