[vtkusers] Color of isosurface

Mon Jul 2 15:17:51 EDT 2012

Ok.  I'll try this, but I'm confused why the same code (and identical
subclass of vtkImplicitFunction) of my subclassed QVTKWidget would
display in red and not have this issue.

On Mon, Jul 2, 2012 at 12:13 PM, Bill Lorensen <bill.lorensen at gmail.com> wrote:
> 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
>> >>>> _______________________________________________
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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:
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>> >
>> >
>> >
>> > --
>> > 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
>

-- 
“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