[vtk-developers] vtkChartXY lines not visible when using logarithmic x axis
Andrew Maclean
andrew.amaclean at gmail.com
Tue Jul 26 04:57:43 EDT 2016
Hi Hagen, Mathieu,
I agree with you, if I zoom in when the logarithmic axis is disabled, the
thick line vanishes, however if you look carefully there is a very faint
thin line. It may be (2) as you outline below.
Regards
Andrew
Andrew Maclean
On 26 Jul 2016 5:02 pm, "Hagen Mölle" <h.moelle at googlemail.com> wrote:
> Hi Andrew, Hi Mathieu,
>
> That's exactly the behaviour I see. By the way I am using ATI/AMD video
> cards in my Windows/Linux machine.
>
> !!!! UPDATE: The error also occurs when logarithmic x axis is not enabled.
> But you have to zoom in a lot more. See attached pictures. I am sorry for
> not realizing this earlier.
>
>
> I am not that familiar with OpenGL. But I can imagine two things:
>
> (1) Line is clipped
> (2) If shaders are used to draw the line thickness it might be a floating
> point precision problem. Actually this could be the problem because the
> line thickness starts fluctuating at some point of zoom level before it
> finally disappears. See attached picture. The line thickness is about the
> half the original line thickness.
>
>
> I hope this helps to fix the bug. One might also contact Marcus D.
> Hanwell. He is the developer who mainly implemented vtkCharts. I am not
> sure if he is still responsible.
>
> Hagen
>
>
> On 26.07.2016 01:52, Andrew Maclean wrote:
>
> Hi Hagen,
> I just tested your example and I get similar behaviou using an NVIDIA
> Video card, OpenGL2, VS2015 and the VTK Master.
>
> I can zoom in and, at some point the line disappears, but zooming out
> immediately restores the line.
>
> It seeme to me that once a certain zoom level is reached the line is not
> drawn, however zooming out restores it.
>
> Attached are two pngs showing the effect.When the line disappears it
> should still be visible as the scales on the axes have only changed
> slightly.
>
> Andrew
>
> ---------- Forwarded message ----------
>> From: "Hagen Mölle" <h.moelle at googlemail.com>
>> To: vtk-developers at vtk.org
>> Cc:
>> Date: Mon, 25 Jul 2016 10:14:21 +0200
>> Subject: [vtk-developers] vtkChartXY lines not visible when using
>> logarithmic x axis
>> Hi,
>>
>> Due to spam reasons the bug tracker's user login is disabled right now.
>> One should send bug reports to the vtk's user mailing list, which I did
>> twice. My bug report was totally ignored. That's why I send it here again.
>> Hopefully someone can finally create a ticket in the bug tracker. Thanks.
>>
>> I want to report a bug for vtkChartXY. So I already send this Email two
>> days ago to the vtkUsers mailing list without receiving any answer. The bug
>> is not visible in the vtk bug tracker too. Thus I send the Email again.
>>
>> Bug environment:
>> a) I am using VTK 6.2. I checked my test code on machines running Windows
>> 7 (Visual Studio 2012/2015) and Ubuntu 15.10/Ubuntu 16.04 (gcc). On all
>> these systems the bug is visible.
>> b) I can also reproduce the bug in VTK 7.0 (here I used an Ubuntu 16.04
>> machine and compiled VTK 7.0 using OpenGL2 interface).
>>
>> Bug description:
>>
>> I am using vtkChartXY to display one line. I also enabled logarithmic x
>> axis (chartXY->GetAxis(vtkAxis::BOTTOM)->SetLogScale(true);). Nothing more
>> special. In the compiled application I start zooming into the chart using
>> the mouse wheel, making sure I always have a line displayed in the view. At
>> some zoom level this line just disappears. At the zoom level the line
>> disappears I did the following:
>>
>> 1. Zooming more into the chart the line will not appear again.
>> 2. Zooming out twice (with mouse wheel) the line will reappear.
>>
>> How to reproduce the bug:
>>
>> I basically used the LinePlot example for vtkChartXY (see
>> http://www.vtk.org/Wiki/VTK/Examples/Cxx/Plotting/LinePlot).
>>
>> I added one line to the example code marked with *** (line was added
>> after line 54 in example code).
>> I added the full code to the end of the Email.
>> ---------------
>>
>> // Add multiple line plots, setting the colors etc
>> vtkSmartPointer<vtkChartXY > chart= vtkSmartPointer<vtkChartXY
>> >::New(); *** chart.Get()->GetAxis(vtkAxis::BOTTOM)->SetLogScale(true);
>> view->GetScene()->AddItem(chart);
>>
>> ---------------
>>
>> Compile and execute the program. See my bug description above to
>> visualize the bug.
>>
>>
>> Please contact me if you need more information. I can also provide images
>> of the bug if needed.
>> I hope the bug can be fixed.
>>
>> Hagen.
>>
>>
>>
>>
>> #include <vtkVersion.h>
>> #include <vtkRenderer.h>
>> #include <vtkRenderWindowInteractor.h>
>> #include <vtkRenderWindow.h>
>> #include <vtkSmartPointer.h>
>> #include <vtkChartXY.h>
>> #include <vtkAxis.h>
>> #include <vtkTable.h>
>> #include <vtkPlot.h>
>> #include <vtkFloatArray.h>
>> #include <vtkContextView.h>
>> #include <vtkContextScene.h>
>> #include <vtkPen.h>
>>
>> int main(int, char *[])
>> {
>> // Create a table with some points in it
>> vtkSmartPointer<vtkTable> table =
>> vtkSmartPointer<vtkTable>::New();
>>
>> vtkSmartPointer<vtkFloatArray> arrX =
>> vtkSmartPointer<vtkFloatArray>::New();
>> arrX->SetName("X Axis");
>> table->AddColumn(arrX);
>>
>> vtkSmartPointer<vtkFloatArray> arrC =
>> vtkSmartPointer<vtkFloatArray>::New();
>> arrC->SetName("Cosine");
>> table->AddColumn(arrC);
>>
>> vtkSmartPointer<vtkFloatArray> arrS =
>> vtkSmartPointer<vtkFloatArray>::New();
>> arrS->SetName("Sine");
>> table->AddColumn(arrS);
>>
>> // Fill in the table with some example values
>> int numPoints = 69;
>> float inc = 7.5 / (numPoints-1);
>> table->SetNumberOfRows(numPoints);
>> for (int i = 0; i < numPoints; ++i)
>> {
>> table->SetValue(i, 0, i * inc);
>> table->SetValue(i, 1, cos(i * inc));
>> table->SetValue(i, 2, sin(i * inc));
>> }
>>
>> // Set up the view
>> vtkSmartPointer<vtkContextView> view =
>> vtkSmartPointer<vtkContextView>::New();
>> view->GetRenderer()->SetBackground(1.0, 1.0, 1.0);
>>
>> // Add multiple line plots, setting the colors etc
>> vtkSmartPointer<vtkChartXY> chart =
>> vtkSmartPointer<vtkChartXY>::New();
>> chart.Get()->GetAxis(vtkAxis::BOTTOM)->SetLogScale(true);
>> view->GetScene()->AddItem(chart);
>> vtkPlot *line = chart->AddPlot(vtkChart::LINE);
>> #if VTK_MAJOR_VERSION <= 5
>> line->SetInput(table, 0, 1);
>> #else
>> line->SetInputData(table, 0, 1);
>> #endif
>> line->SetColor(0, 255, 0, 255);
>> line->SetWidth(1.0);
>> line = chart->AddPlot(vtkChart::LINE);
>> #if VTK_MAJOR_VERSION <= 5
>> line->SetInput(table, 0, 2);
>> #else
>> line->SetInputData(table, 0, 2);
>> #endif
>> line->SetColor(255, 0, 0, 255);
>> line->SetWidth(5.0);
>>
>> // For dotted line, the line type can be from 2 to 5 for different
>> dash/dot
>> // patterns (see enum in vtkPen containing DASH_LINE, value 2):
>> #ifndef WIN32
>> line->GetPen()->SetLineType(vtkPen::DASH_LINE);
>> #endif
>> // (ifdef-ed out on Windows because DASH_LINE does not work on Windows
>> // machines with built-in Intel HD graphics card...)
>>
>> //view->GetRenderWindow()->SetMultiSamples(0);
>>
>> // Start interactor
>> view->GetInteractor()->Initialize();
>> view->GetInteractor()->Start();
>>
>> return EXIT_SUCCESS;
>> }
>>
>>
>> _______________________________________________
>> Powered by www.kitware.com
>>
>> Visit other Kitware open-source projects at
>> http://www.kitware.com/opensource/opensource.html
>>
>> Search the list archives at: http://markmail.org/search/?q=vtk-developers
>>
>> Follow this link to subscribe/unsubscribe:
>> http://public.kitware.com/mailman/listinfo/vtk-developers
>>
>
>
>
> --
> ___________________________________________
> Andrew J. P. Maclean
>
> ___________________________________________
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/vtk-developers/attachments/20160726/2e767586/attachment.html>
More information about the vtk-developers
mailing list