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FunctionParser

vtk-examples/Cxx/Utilities/FunctionParser

Description

This example shows how to substitute values and evaluate a string such as "a+b".

Other languages

See (Java)

Question

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

Code

FunctionParser.cxx

#include <vtkFunctionParser.h>
#include <vtkNew.h>

int main(int, char*[])
{
  vtkNew<vtkFunctionParser> functionParser;
  functionParser->SetFunction("a+b");

  functionParser->SetScalarVariableValue("a", 2);
  functionParser->SetScalarVariableValue("b", 3);

  double result = functionParser->GetScalarResult();

  std::cout << "result: " << result << std::endl;

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(FunctionParser)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonMisc
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping FunctionParser: ${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(FunctionParser MACOSX_BUNDLE FunctionParser.cxx )
  target_link_libraries(FunctionParser 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(FunctionParser MACOSX_BUNDLE FunctionParser.cxx )
  target_link_libraries(FunctionParser PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS FunctionParser
    MODULES ${VTK_LIBRARIES}
    )
endif()

Download and Build FunctionParser

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

cd FunctionParser/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:

./FunctionParser

WINDOWS USERS

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