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

#include <algorithm>

#if VTK_VERSION_NUMBER >= 90220220630ULL
#define VTK_HAS_SETCOLORF 1
#endif

//----------------------------------------------------------------------------
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");
#if VTK_HAS_SETCOLORF
  area->GetBrush()->SetColorF(color3d.GetRed(), color3d.GetGreen(),
                              color3d.GetBlue(), 0.6);
#else
  area->GetBrush()->SetColor(color3d.GetRed(), color3d.GetGreen(),
                             color3d.GetBlue(), 0.6);
#endif

  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 
  ChartsCore
  CommonColor
  CommonCore
  CommonDataModel
  InteractionStyle
  RenderingContext2D
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
  ViewsContext2D
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "AreaPlot: Unable to find the VTK build folder.")
endif()

# 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}
)

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.