Scalars
vtk-examples/Cxx/VTKConcepts/Scalars
Question
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Code¶
Scalars.cxx
#include <vtkDoubleArray.h>
#include <vtkFloatArray.h>
#include <vtkNew.h>
#include <vtkPointData.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
void TypeSpecific();
void NonTypeSpecific();
int main(int, char*[])
{
TypeSpecific();
NonTypeSpecific();
return EXIT_SUCCESS;
}
void TypeSpecific()
{
// Create a point set
vtkNew<vtkPoints> points;
points->InsertNextPoint(0, 0, 0);
points->InsertNextPoint(1, 0, 0);
vtkNew<vtkPolyData> polydata;
polydata->SetPoints(points);
vtkNew<vtkDoubleArray> weights;
weights->SetNumberOfValues(2);
weights->SetValue(0, 1);
weights->SetValue(1, 2);
polydata->GetPointData()->SetScalars(weights);
double weight =
dynamic_cast<vtkDoubleArray*>(polydata->GetPointData()->GetScalars())
->GetValue(0);
std::cout << "double weight: " << weight << std::endl;
/*
// This causes a crash because the array is not a vtkFloatArray
double weightf =
dynamic_cast<vtkFloatArray*>(polydata->GetPointData()->GetScalars())->GetValue(0);
std::cout << "float weight: " << weightf << std::endl;
*/
}
void NonTypeSpecific()
{
// Create a point set
vtkNew<vtkPoints> points;
points->InsertNextPoint(0, 0, 0);
points->InsertNextPoint(1, 0, 0);
vtkNew<vtkPolyData> polydata;
polydata->SetPoints(points);
vtkNew<vtkDoubleArray> weights;
weights->SetNumberOfValues(2);
weights->SetValue(0, 1);
weights->SetValue(1, 2);
polydata->GetPointData()->SetScalars(weights);
double weight = polydata->GetPointData()->GetScalars()->GetComponent(0, 0);
std::cout << "double weight: " << weight << std::endl;
double weightf = polydata->GetPointData()->GetScalars()->GetComponent(0, 0);
std::cout << "float weight: " << weightf << std::endl;
}
CMakeLists.txt¶
cmake_minimum_required(VERSION 3.12 FATAL_ERROR)
project(Scalars)
find_package(VTK COMPONENTS
CommonCore
CommonDataModel
)
if (NOT VTK_FOUND)
message(FATAL_ERROR "Scalars: 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(Scalars MACOSX_BUNDLE Scalars.cxx )
target_link_libraries(Scalars PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
TARGETS Scalars
MODULES ${VTK_LIBRARIES}
)
Download and Build Scalars¶
Click here to download Scalars and its CMakeLists.txt file. Once the tarball Scalars.tar has been downloaded and extracted,
cd Scalars/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:
./Scalars
WINDOWS USERS
Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.