[vtkusers] vtkTexture mapping with grayscale

[Tim Hutton]

If that doesn't work, try filling the image with vtkUnsignedCharArray 
instead of vtkFloatArray. This triggers VTK to treat it as 0-255 grey-level 
data and it will render correctly without requiring a lookup table at all. 
It took me ages to work this out.

This answer works in vtk4.0. It seems you are using vtk3.2 or earlier, try 
calling

scalars->SetDataTypeToUnsignedChar();

before filling with 0-255 grey-levels.

Tim.

At 11:35 28/02/2002 +0100, Fabrice Vincent wrote:
>I don't know where the color comes from but
>you can try  to  assign the lookuptable to  the texture ( 
>texture->SetLookUpTable(lut))
>instead of the mapper
>
>
>Fabrice
>
>William Jacob Proctor wrote:
>
>>I am trying to map a 2D texture onto a plane in grayscale but I can't seem
>>to keep it from mapping to colors.  Can anyone tell me where the color is
>>coming from in the code below and how I could make the mapping grayscale?
>>Thanks!
>>
>>     -- Jake
>>
>>
>>#include <stdio.h>
>>#include <vtkRenderer.h>
>>#include <vtkRenderWindow.h>
>>#include <vtkRenderWindowInteractor.h>
>>#include <vtkPolyDataMapper.h>
>>#include <vtkActor.h>
>>#include <vtkInteractorStyleTrackball.h>
>>#include <vtkScalars.h>
>>#include <vtkStructuredPoints.h>
>>#include <vtkPlaneSource.h>
>>#include <vtkLookupTable.h>
>>
>>main()
>>{
>>                 vtkStructuredPoints *image2d = vtkStructuredPoints::New();
>>                         image2d->SetDimensions (256,256,1);
>>                         vtkScalars *s = vtkScalars::New(VTK_INT, 1);
>>                                 s->SetNumberOfScalars (65536);
>>                         int j, k;
>>                         for (j = k = 0; k < 65536; k++)
>>                         {
>>                                 s->SetScalar (j++, k);
>>                         }
>>                         image2d->GetPointData()->SetScalars (s);
>>
>>
>>        vtkPlaneSource *plane2d = vtkPlaneSource::New();
>>         plane2d->SetXResolution (1);
>>         plane2d->SetYResolution (1);
>>
>>                 vtkLookupTable *lut = vtkLookupTable::New();
>>         //              lut->SetTableRange (0, 1000);
>>                         lut->SetHueRange (0., 0.);
>>                         lut->SetSaturationRange (0., 0.);
>>                         lut->SetValueRange(0., 1.);
>>
>>        vtkPolyDataMapper *mapper2d = vtkPolyDataMapper::New();
>>            mapper2d->SetInput (plane2d->GetOutput());
>>                         mapper2d->ScalarVisibilityOff();
>>                         mapper2d->ImmediateModeRenderingOn();
>>                         mapper2d->SetLookupTable (lut);
>>
>>        vtkTexture *texture2d = vtkTexture::New();
>>                         texture2d->SetInput (image2d);
>>                         texture2d->MapColorScalarsThroughLookupTableOff();
>>
>>
>>        vtkActor *actor2d = vtkActor::New();
>>            actor2d->SetMapper (mapper2d);
>>            actor2d->SetTexture (texture2d);
>>         //   actor2d->GetProperty()->SetColor (0., 0., 1.);
>>
>>        vtkRenderer *renderer2d = vtkRenderer::New();
>>            renderer2d->SetBackground (0.1, 0.1, 0.1);
>>            renderer2d->AddActor (actor2d);
>>
>>        vtkRenderWindow *canvas2d = vtkRenderWindow::New();
>>            canvas2d->AddRenderer (renderer2d);
>>            canvas2d->SetSize (256, 256);
>>
>>        vtkInteractorStyleTrackball
>>            *trackball2d = vtkInteractorStyleTrackball::New();
>>            trackball2d->SetTrackballModeToTrackball();
>>
>>        vtkRenderWindowInteractor
>>                                 *interactor2d =
>>vtkRenderWindowInteractor::New();
>>            interactor2d->SetRenderWindow (canvas2d);
>>            interactor2d->SetInteractorStyle (trackball2d);
>>
>>                 interactor2d->Start();
>>
>>}
>>
>>
>>
>>
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>
>
>
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