[vtkusers] Cannot disable vtkPolyDataMapper2D scalar visibility using VTK OpenGL2 backend

[Ken Martin]

Sounds like a bug. Andras if you move line 568 from
vtkOpenGLPolyDataMapper2D.cxx out of the if statement to line 563 does that
solve the problem? Looking at the code I believe that is the correct fix.

e.g. it should look like this

  this->MapScalars(act->GetProperty()->GetOpacity());
  this->HaveCellScalars = false;
  if (this->ScalarVisibility)
  {
    // We must figure out how the scalars should be mapped to the polydata.
    if ( (this->ScalarMode == VTK_SCALAR_MODE_USE_CELL_DATA ||
          this->ScalarMode == VTK_SCALAR_MODE_USE_CELL_FIELD_DATA ||



On Mon, Jul 9, 2018 at 12:33 PM, Andras Lasso <lasso at queensu.ca> wrote:

> Hi all,
>
>
>
> I try to render a polydata with a plain solid color using a 2D actor.
> However, it seems that with OpenGL2 rendering backend, if a polydata has
> scalars and rendered once with scalar visibility enabled, ScalarVisibility
> cannot be disabled anymore. The actor will always appear as colored. In
> some cases, the colors randomly flicker. See a very simple code snippet
> below to reproduce it.
>
>
>
> The same code works well (scalar visibility can be enabled/disabled) using
> VTK OpenGL1 backend. If I use 3D mapper and actor (vtkPolyDataMapper and
> vtk.vtkActor) then it works well using both VTK OpenGL1 and OpenGL2
> backends.
>
>
>
> Is this a known issue? Could somebody have a look?
>
>
>
> Thank you,
>
> Andras
>
>
>
>
>
> reader = vtk.vtkXMLPolyDataReader()
>
> reader.SetFileName("scalartest.vtp")
>
> mapper = vtk.vtkPolyDataMapper2D()
>
> mapper.SetInputConnection(reader.GetOutputPort())
>
> actor = vtk.vtkActor2D()
>
> actor.SetMapper(mapper)
>
> actor.SetPosition(150,150)
>
> ren = vtk.vtkRenderer()
>
> ren.AddActor(actor)
>
> renWin = vtk.vtkRenderWindow()
>
> renWin.AddRenderer(ren)
>
> renWin.Render()
>
> # actor appears in color here => OK
>
> mapper.SetScalarVisibility(False)
>
> renWin.Render()
>
> # actor appears in color here => ERROR (it should be white)
>
>
>
>
>
> Download link for scalartest.vtp sample data set (any other polydata with
> scalars should work):
>
> https://1drv.ms/u/s!Arm_AFxB9yqHtK1gHCIsGt0U62OTQg
>
>
>
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-- 
Ken Martin PhD
Distinguished Engineer
Kitware Inc.
101 East Weaver Street
Carrboro, North Carolina
27510 USA

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