[vtk-developers] proposed ENH to vtkImagePlaneWidget

[Dean Inglis]

Hi all,

I can add a couple of lines to vtkImagePlaneWidget in
::GenerateTexturePlane() that
will enable transparency:

<snip>
  this->ColorMap->SetLookupTable(this->LookupTable);
  this->ColorMap->SetOutputFormatToRGBA();
  this->ColorMap->PassAlphaToOutputOn();
<snip>

and further down:
<snip>
  this->Texture->SetQualityTo32Bit();
  if ( this->GrayScaleEnabled )
    {
    this->Texture->MapColorScalarsThroughLookupTableOff();
    }
  else
    {
    this->Texture->MapColorScalarsThroughLookupTableOn();
    }
  this->Texture->SetInterpolate(this->TextureInterpolate);
  this->Texture->RepeatOff();
  this->Texture->SetLookupTable(this->LookupTable);
<snip>

where GrayScaleEnabled is an ivar accessable through the API.
Then, for example, one could either build a vtkLookupTable, and
set it to the widget or retrieve the widget's internal lut:
 lut = widget->GetLookupTable();
 lut->SetValue(0,0,0,0,0);
to make voxels of value '0' invisible.  The only problem(?) may
be with any subsequent window-levelling.

Any thoughts? Should GrayScaleEnabled be changed to
TransparencyEnabled or something else?

Dean


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dean Inglis, Ph.D.
Clinical Research Unit
25 Charlton Avenue East, Unit 610
Hamilton, ONT, L8N 1Y2
tel: (905) 527-0028
fax: (905) 521-1297
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~