AreaPlot

Description¶

This example illustrates vtkPlotArea, which draws a filled region between two curves. The example uses a valid mask to select the values to define the region to be plotted.

The example also shows how to control the size and colors of the plot's components.

Code¶

AreaPlot.cxx

#include <vtkNew.h>
#include <vtkPlotArea.h>

#include <vtkNamedColors.h>

#include <vtkChartXY.h>
#include <vtkAxis.h>
#include <vtkBrush.h>
#include <vtkCharArray.h>
#include <vtkContextScene.h>
#include <vtkContextView.h>
#include <vtkFloatArray.h>
#include <vtkPlot.h>
#include <vtkTextProperty.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkTable.h>

#include <algorithm>
//----------------------------------------------------------------------------
int main( int, char * [] )
{
  vtkNew<vtkNamedColors> colors;

  // Set up a 2D scene, add an XY chart to it
  vtkNew<vtkContextView> view;
  view->GetRenderWindow()->SetSize(640, 480);

  vtkNew<vtkChartXY> chart;
  chart->SetTitle("Area Plot");
  chart->GetTitleProperties()->SetFontSize(36);
  chart->GetTitleProperties()->SetColor(colors->GetColor3d("Banana").GetData());

  chart->GetAxis(0)->GetTitleProperties()->SetFontSize(24);
  chart->GetAxis(0)->GetTitleProperties()->SetColor(colors->GetColor3d("orange").GetData());
  chart->GetAxis(0)->GetLabelProperties()->SetColor(colors->GetColor3d("beige").GetData());
  chart->GetAxis(0)->GetLabelProperties()->SetFontSize(18);

  chart->GetAxis(1)->GetTitleProperties()->SetFontSize(24);
  chart->GetAxis(1)->GetTitleProperties()->SetColor(colors->GetColor3d("orange").GetData());
  chart->GetAxis(1)->GetLabelProperties()->SetColor(colors->GetColor3d("beige").GetData());
  chart->GetAxis(1)->GetLabelProperties()->SetFontSize(18);

  view->GetScene()->AddItem(chart);

  // Create a table with some points in it...
  vtkNew<vtkTable> table;

  vtkNew<vtkFloatArray> arrX;
  arrX->SetName("X Axis");
  table->AddColumn(arrX);

  vtkNew<vtkFloatArray> arrC;
  arrC->SetName("Cosine");
  table->AddColumn(arrC);

  vtkNew<vtkFloatArray> arrS;
  arrS->SetName("Sine");
  table->AddColumn(arrS);

  vtkNew<vtkFloatArray> arrS2;
  arrS2->SetName("Sine2");
  table->AddColumn(arrS2);

  vtkNew<vtkFloatArray> arrS3;
  arrS3->SetName("Sine3");
  table->AddColumn(arrS3);

  vtkNew<vtkFloatArray> arr1;
  arr1->SetName("One");
  table->AddColumn(arr1);

  vtkNew<vtkCharArray> validMask;
  validMask->SetName("ValidMask");
  table->AddColumn(validMask);

  // Test charting with a few more points...
  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 + 0.01);
    table->SetValue(i, 1, cos(i * inc) + 0.01);
    table->SetValue(i, 2, sin(i * inc) + 0.01);
    table->SetValue(i, 3, sin(i * inc) + 0.5);
    table->SetValue(i, 4, sin(i * inc) * sin(i * inc) + 0.01);
    table->SetValue(i, 5, 1.0);

    validMask->SetValue(i, (i > 30 && i < 40) ? 0 : 1);
  }

  // Add multiple line plots, setting the colors etc
  vtkColor3d color3d = colors->GetColor3d("tomato");
  vtkPlotArea* area = vtkPlotArea::SafeDownCast(chart->AddPlot(vtkChart::AREA));
  area->SetInputData(table);
  area->SetInputArray(0, "X Axis");
  area->SetInputArray(1, "Sine");
  area->SetInputArray(2, "Sine2");
  area->SetValidPointMaskName("ValidMask");
  area->GetBrush()->SetColorF(color3d.GetRed(),
                              color3d.GetGreen(),
                              color3d.GetBlue(),
                              .6);

  chart->GetAxis(vtkAxis::LEFT)->SetLogScale(true);

  // Render the scene and compare the image to a reference image
  view->GetRenderer()->SetBackground(colors->GetColor3d("SlateGray").GetData());
  view->GetRenderWindow()->SetMultiSamples(0);
  view->GetRenderWindow()->Render();
  view->GetInteractor()->Initialize();
  view->GetInteractor()->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt¶

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(AreaPlot)

find_package(VTK COMPONENTS 
  vtkChartsCore
  vtkCommonColor
  vtkCommonCore
  vtkCommonDataModel
  vtkInteractionStyle
  vtkRenderingContext2D
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2
  vtkViewsContext2D QUIET)
if (NOT VTK_FOUND)
  message("Skipping AreaPlot: ${VTK_NOT_FOUND_MESSAGE}")
  return ()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
  # old system
  include(${VTK_USE_FILE})
  add_executable(AreaPlot MACOSX_BUNDLE AreaPlot.cxx )
  target_link_libraries(AreaPlot PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(AreaPlot MACOSX_BUNDLE AreaPlot.cxx )
  target_link_libraries(AreaPlot PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS AreaPlot
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build AreaPlot¶

Click here to download AreaPlot and its CMakeLists.txt file. Once the tarball AreaPlot.tar has been downloaded and extracted,

cd AreaPlot/build

If VTK is installed:

cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

make

and run it:

./AreaPlot

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.