FW: [vtkusers] why doesn't my glyph scale?

[John Platt]

-----Original Message-----
From: John Platt [mailto:jcplatt at lineone.net] 
Sent: 19 April 2005 10:27
To: 'Akiko Campbell'
Subject: RE: [vtkusers] why doesn't my glyph scale?

 

Hi Akiko,

 

Try replacing

 

points->GetCellData()->SetScalars( eigenValue_1 );

with

points->GetPointData()->SetScalars( eigenValue_1 );

 

Below is an extract of some glyph code - the comments may be helpful.

  

      // The glyphs can be oriented along the input DataSet vectors or
normals.

      // Since spheres have no preferred orientation, switch orientation
off.

 

      m_vtkGlyphs->OrientOff();

 

      // The glyphs must be scaled otherwise each glyph will be drawn in

      // World coordinates. Note that scaling is ON by default.

 

      m_vtkGlyphs->ScalingOn();  

 

      // Scaling is controlled by the composite factor ScaleFactor *
DataScale

      // where the data scale is either

      //

      //          - point scalars (VTK_SCALE_BY_SCALAR)

      //          - point vector magnitude (VTK_SCALE_BY_VECTOR)

      //          - point vector components
(VTK_SCALE_BY_VECTORCOMPONENTS)

      //

      // Scaling due to data (scalars, vectors, or normals can be
disabled

      // using SetScaleModeToDataScalingOff()). The glyph scale can also
be

      // controlled by mapping the data scale to a specified range, then

      // multiplying by the scale factor.

 

John.

 

-----Original Message-----
From: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] On
Behalf Of Akiko Campbell
Sent: 19 April 2005 00:32
To: vtkusers at vtk.org
Subject: [vtkusers] why doesn't my glyph scale?

 

Hello,

 

I have a set of points I'd like to visualize with glyphs but glyphs
don't seem to scale at all. I read in point's vector components into a
float array (eigenVector_1) and corresponding magnitude data into
another float array (eigenValue_1).  Since magnitude information is
stored in a separate array as scalars, I would like to use
SetScaleModeToScaleByScalar() to scale glyphs but all glyphs are exactly
the same shape and are directed in the same direction.  I am wondering
if something I'm doing is wrong here.  Could someone give me an insight?
Thank you!

 

vtkPolyData *points = reader->GetOutput();

const unsigned int numberOfPoints = vpoints->GetNumberOfPoints();

vtkFloatArray *eigenVector_1 = vtkFloatArray::New();

eigenVector_1->SetNumberOfComponents( 3 );

eigenVector_1->SetNumberOfTuples( numberOfPoints );

vtkFloatArray *eigenValue_1 = vtkFloatArray::New();

eigenValue_1->SetNumberOfTuples( numberOfPoints );

//************************************************

A brief version of loop to populate the arrays:

 

for (unsigned int ctr=0; ctr < numberOfPoints; ctr++){

 eigenVector_1->SetComponent( ctr, 0, voxelValue_1_X[X] );

 eigenVector_1->SetComponent( ctr, 1, voxelValue_1_Y[Y] );

 eigenVector_1->SetComponent( ctr, 2, voxelValue_1_Z[Z] );

 

 eigenValue_1->SetValue( ctr, pixelValue[X] );

}

//************************************************

 

//Set the vectors and scalars 

points->GetPointData()->SetVectors( eigenVector_1 ); 

points->GetCellData()->SetScalars( eigenValue_1 );

 

vtkSphereSource *source = vtkSphereSource::New();

source->SetThetaResolution( 6 );

source->SetPhiResolution( 5 );

source->SetRadius( 0.5 );

vtkGlyph3D *glyph = vtkGlyph3D::New();

glyph->SetInput(points);

glyph->SetSource(source->GetOutput());

glyph->ScalingOff(); // I read somewhere I need to set this off.even
with ScalingOn(), no scaling happens. 

glyph->OrientOn();

glyph->SetVectorModeToUseVector();

glyph->SetScaleModeToScaleByScalar();

glyph->SetColorModeToColorByScalar();

glyph->Update();


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