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.

Question

If you have a question about this example, please use the VTK Discourse Forum

Code¶

AreaPlot.cxx

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

#include <vtkNamedColors.h>

#include <vtkAxis.h>
#include <vtkBrush.h>
#include <vtkCharArray.h>
#include <vtkChartXY.h>
#include <vtkContextScene.h>
#include <vtkContextView.h>
#include <vtkFloatArray.h>
#include <vtkNew.h>
#include <vtkPlot.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkTable.h>
#include <vtkTextProperty.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);
  view->GetRenderWindow()->SetWindowName("AreaPlot");

  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 =
      dynamic_cast<vtkPlotArea*>(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 3.12 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()
  # Prevent a "command line is too long" failure in Windows.
  set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
  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.