[vtkusers] vtkChart large axis ranges

[Andrew Ward]

Hi Marcus,

Here is some code to reproduce the problem. Changing the RANGE_HIGH define
to 1e11 causes the plot to render incorrectly and the function to
disappear. I tried removing the relevant code in
vtkChart::CalculatePlotTransform, which helped with this range, but there
were still problems with the full float32 range.

Regards,

Andrew Ward.


#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkSmartPointer.h>
#include <vtkContextView.h>
#include <vtkContextScene.h>
#include <vtkPiecewiseFunctionItem.h>
#include <vtkPiecewiseControlPointsItem.h>
#include <vtkPiecewiseFunction.h>
#include <vtkChartXY.h>
#include <vtkAxis.h>
#include <vtkTextProperty.h>
#include <vtkPlotBar.h>
#include <vtkPen.h>
#include <vtkBrush.h>
#include <vtkTable.h>
#include <vtkFloatArray.h>

#define RANGE_LOW -1e4

// Change this value to 1e11 and the bar plot renders incorrectly, plus the
// piecewise function points disappear.
#define RANGE_HIGH 1e9

vtkSmartPointer< vtkChartXY > GetNewChart()
{
    vtkSmartPointer< vtkChartXY > chart = vtkSmartPointer< vtkChartXY
>::New();

    vtkAxis *yAxis = chart->GetAxis(vtkAxis::LEFT);
    vtkAxis *xAxis = chart->GetAxis(vtkAxis::BOTTOM);

    xAxis->SetRange( RANGE_LOW, RANGE_HIGH);
    xAxis->SetMinimumLimit( RANGE_LOW );
    xAxis->SetMaximumLimit( RANGE_HIGH );
    xAxis->SetBehavior(vtkAxis::FIXED);
    yAxis->SetRange(0.0, 1.0);
    yAxis->SetBehavior(vtkAxis::FIXED);

    vtkSmartPointer< vtkTable > table = vtkSmartPointer< vtkTable >::New();
    table->Initialize();

    vtkSmartPointer< vtkFloatArray > xs =
        vtkSmartPointer< vtkFloatArray >::New();
    xs->SetName("X");
    table->AddColumn(xs);

    vtkSmartPointer< vtkFloatArray > ys =
        vtkSmartPointer< vtkFloatArray >::New();
    ys->SetName("Y");
    table->AddColumn(ys);

    double halfRange = ((RANGE_HIGH - RANGE_LOW) / 2.0);

    table->SetNumberOfRows(3);
    table->SetValue(0, 0, RANGE_LOW);
    table->SetValue(0, 1, 0.5);
    table->SetValue(1, 0, RANGE_LOW + halfRange);
    table->SetValue(1, 1, 1.0);
    table->SetValue(2, 0, RANGE_HIGH);
    table->SetValue(2, 1, 0.2);

    vtkSmartPointer< vtkPlotBar > plot = vtkSmartPointer< vtkPlotBar
>::New();
    plot->SetInputData(table, 0, 1);
    plot->GetPen()->SetLineType(vtkPen::NO_PEN);
    plot->GetBrush()->SetColorF(0.0, 0.0, 0.0, 0.25);
    chart->AddPlot(plot);

    vtkSmartPointer<vtkPiecewiseFunction> f =
        vtkSmartPointer<vtkPiecewiseFunction>::New();
    f->AddPoint(RANGE_LOW, 0.2);
    f->AddPoint(RANGE_LOW + halfRange, 0.5);
    f->AddPoint(RANGE_HIGH, 0.9);

    vtkSmartPointer< vtkPiecewiseFunctionItem > opacityFunctionItem =
        vtkSmartPointer< vtkPiecewiseFunctionItem >::New();
    opacityFunctionItem->SetPiecewiseFunction(f);
    chart->AddPlot(opacityFunctionItem);

    vtkSmartPointer< vtkPiecewiseControlPointsItem > controlPoints =
        vtkSmartPointer< vtkPiecewiseControlPointsItem >::New();
    controlPoints->SetPiecewiseFunction(f);
    chart->AddPlot(controlPoints);

    return chart;
}

int main(int, char *[])
{
  vtkSmartPointer<vtkContextView> view =
vtkSmartPointer<vtkContextView>::New();
  view->GetRenderer()->SetBackground(1.0, 1.0, 1.0);
  view->GetRenderWindow()->SetSize(800, 600);
  view->GetScene()->AddItem(GetNewChart());
  view->GetRenderWindow()->GetInteractor()->Initialize();
  view->GetRenderWindow()->GetInteractor()->CreateOneShotTimer(10);
  view->GetRenderWindow()->GetInteractor()->Start();
}



On 23 May 2014 05:49, Marcus D. Hanwell <marcus.hanwell at kitware.com> wrote:

> On Mon, May 19, 2014 at 8:48 PM, Andrew Ward
> <andrew.derek.ward at gmail.com> wrote:
> > Hello,
> >
> > I am attempting to use a vtkChartXY with an x-axis in the range of 32-bit
> > floating-point numbers (-3.40282e+038 to 3.40282e+038), however when
> adding
> > values with a range greater than 1e10, the chart fails to render
> properly.
> >
> > I tracked one possible problem down to vtkChart::CalculatePlotTransform,
> > where the scaling factor is altered for large ranges, which at least
> > explains why the issue appears over the 1e10 limit, but I am at a loss
> as to
> > whether this is a bug, or whether I am using the chart incorrectly.
> >
> > Any suggestions much appreciated,
> >
> I wrote most of this code, if you could supply a few lines of code to
> trigger it I will take a look. The scaling is there to support double
> precision data that needs to be plotted and it sounds like my tests
> miss a case that is hitting you here.
>
> Thanks,
>
> Marcus
>
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