[vtk-developers] vtkChartXY lines not visible when using logarithmic x axis
Hagen Mölle
h.moelle at googlemail.com
Tue Jul 26 05:19:53 EDT 2016
Hi Andrew, Hi Mathieu,
I can not see the line after it disappears. This might be a special
feature of the open source radeon graphics driver under Linux.
Just for completeness one can easily see the line thickness fluctuation
by zooming into the scene just right before the line disappears. At this
zoom level just drag the scene using the left mouse button and move the
mouse around.
In fact it would be very nice if this bug could be fixed at least when
logarithmic x axis is enabled. Because when logarithmic x axis is
enabled the error is visible after zooming in only a few steps.
Hagen
On 26.07.2016 10:57, Andrew Maclean wrote:
>
> 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
> <mailto: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
>> <mailto:h.moelle at googlemail.com>>
>> To: vtk-developers at vtk.org <mailto: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;
>> }
>>
>>
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>>
>>
>> --
>> ___________________________________________
>> Andrew J. P. Maclean
>>
>> ___________________________________________
>
>
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