[vtkusers] Color of isosurface

[Bill Lorensen]

No. You triangles have have a reversed sense. Usually the inside of the
surface has higher valuse than the outside. If this is not the case, the
triangles will have a reversed sense.

On Mon, Jul 2, 2012 at 3:05 PM, Dale "Luke" Peterson
<hazelnusse at gmail.com>wrote:

> I flipped the sign of the gradient in EvaluateGradient() and nothing
> changed.  That should have the same effect, correct?
>
> On Mon, Jul 2, 2012 at 11:54 AM, Bill Lorensen <bill.lorensen at gmail.com>
> wrote:
> > I'll bet your normals are point "in" rather than "out".  Try
> vtkReverSense
> > on the output of your isosurface.
> >
> >
> > On Mon, Jul 2, 2012 at 2:37 PM, Dale "Luke" Peterson <
> hazelnusse at gmail.com>
> > wrote:
> >> I tried ScalarVisibilityOff() and it didn't fix the problem.  However,
> >> it did make me realize that the problem is different from what I
> >> originally thought.  I've attached two window screen shots, both with
> >> ScalarVisibilityOff().  The only difference is that in the second one,
> >> I've called contourActor->GetProperty()->SetColor(0, 0, 1).  You can
> >> see that the blue color is just barely visible.
> >>
> >> Just to check, I tried setting ScalarVisibilityOn(), and then repeated
> >> the test with and without calling SetColor(0, 0, 1).  In both cases
> >> the surface appears to be very dark but slightly red.  So it seems
> >> like red is the default color for the zero-level curve, but for some
> >> reason, my surface is showing a whole lot darker than I would like.
> >>
> >> Thanks for suggestion and let me know if you have any other ideas.
> >>
> >> Thanks,
> >> ~Luke
> >>
> >>
> >> On Mon, Jul 2, 2012 at 10:51 AM, Jothy <jothybasu at gmail.com> wrote:
> >>> Can you try contourMapper->setScalarVisibilityOff()
> >>>
> >>> Jothy
> >>>
> >>> On 02-Jul-2012, at 5:52 PM, "Dale \"Luke\" Peterson"
> >>> <hazelnusse at gmail.com> wrote:
> >>>
> >>>> I subclassed vtkImplicit function and implemented EvaluateFunction()
> >>>> and EvaluateGradient().  I then use vtkSampleFunction,
> >>>> vtkContourFilter, vtkPolyDataMapper, and vtkActor and add the actor to
> >>>> a renderer.  I am only interested in one iso-surface, the zero
> >>>> iso-surface, and in the past it always displayed in red.  Something
> >>>> changed (likely in my code) but I can't figure out what, and the the
> >>>> surface renders only in black.  I have tried calling
> >>>> GetProperty()->SetColor() on the actor but this has no effect.  I also
> >>>> tried dropping in example code for the vtkSphereSource which shows up
> >>>> blue, as in the tutorial.  Based on this, I'm guessing that there is
> >>>> something going on with vtkSampleFunction, vtkContourFilter, or
> >>>> vtkPolyDataMapper, but I can't figure out what.
> >>>>
> >>>> I am doing all of this in my own subclassed QVTKWidget, and the color
> >>>> used to work fine.  I also have a minimal example of the surface that
> >>>> doesn't use QVTKWidget and it shows the surface in red.  Perhaps there
> >>>> is something strange going on in Qt?
> >>>>
> >>>> Any ideas on what might be going on?
> >>>>
> >>>> The relevant code I have in the constructor of my QVTKWidget subclass
> >>>> is:
> >>>>
> >>>>  configurationSurface =
> vtkSmartPointer<vtkHolonomicConstraint>::New();
> >>>>  sample = vtkSmartPointer<vtkSampleFunction>::New();
> >>>>  sample->SetSampleDimensions(50, 50, 50);
> >>>>  sample->SetImplicitFunction(configurationSurface);
> >>>>  // Create the 0 isosurface
> >>>>  contour = vtkSmartPointer<vtkContourFilter>::New();
> >>>>  contour->SetInputConnection(sample->GetOutputPort());
> >>>>  contour->GenerateValues(1, 0.0, 0.0);
> >>>>  contour->Update();
> >>>>
> >>>>  // Map the contours to graphical primitives
> >>>>  contourMapper = vtkSmartPointer<vtkPolyDataMapper>::New();
> >>>>  contourMapper->SetInputConnection(contour->GetOutputPort());
> >>>>
> >>>>  // Create an actor for the contours
> >>>>  contourActor = vtkActor::New();
> >>>>  contourActor->SetMapper(contourMapper);
> >>>>
> >>>>  // Has no effect: still shows up as black.
> >>>>  contourActor->GetProperty()->SetColor(0,0,1);
> >>>>
> >>>> Thanks,
> >>>> Luke
> >>>>
> >>>>
> >>>> --
> >>>> "People call me a perfectionist, but I'm not. I'm a rightist. I do
> >>>> something until it's right, and then I move on to the next thing."
> >>>> -- James Cameron
> >>>> _______________________________________________
> >>>> Powered by www.kitware.com
> >>>>
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> >>>>
> >>>> Please keep messages on-topic and check the VTK FAQ at:
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> >>
> >>
> >>
> >> --
> >> "People call me a perfectionist, but I'm not. I'm a rightist. I do
> >> something until it's right, and then I move on to the next thing."
> >> -- James Cameron
> >>
> >> _______________________________________________
> >> Powered by www.kitware.com
> >>
> >> Visit other Kitware open-source projects at
> >> http://www.kitware.com/opensource/opensource.html
> >>
> >> Please keep messages on-topic and check the VTK FAQ at:
> >> http://www.vtk.org/Wiki/VTK_FAQ
> >>
> >> Follow this link to subscribe/unsubscribe:
> >> http://www.vtk.org/mailman/listinfo/vtkusers
> >>
> >
> >
> >
> > --
> > Unpaid intern in BillsBasement at noware dot com
>
>
>
> --
> "People call me a perfectionist, but I'm not. I'm a rightist. I do
> something until it's right, and then I move on to the next thing."
> -- James Cameron
>



-- 
Unpaid intern in BillsBasement at noware dot com
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