# ProgrammableSource

vtk-examples/Cxx/Filtering/ProgrammableSource

### Description¶

Use a programmable source to generate the points for the Lorenz System

Question

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

### Code¶

ProgrammableSource.cxx

#include <vtkActor.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProgrammableSource.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkVertexGlyphFilter.h>

// https://en.wikipedia.org/wiki/Lorenz_system
static void Lorenz(void* arg)
{
double sigma = 10.0; /* The Lorenz paramaters */
double beta = 8.0 / 3.0;
double rho = 28.0;
double h = .001; /* Integration step size */

double x, y, z;
double xx, yy, zz;
x = 0.1;
y = 0.1;
z = 0.1;
vtkNew<vtkPoints> points;
// Get to a stable starting point
for (int i = 0; i < 1000; ++i)
{
xx = x + h * sigma * (y - x);
yy = y + h * (x * (rho - z) - y);
zz = z + h * (x * y - (beta * z));
x = xx;
y = yy;
z = zz;
}
for (int i = 0; i < 500000; ++i)
{
xx = x + h * sigma * (y - x);
yy = y + h * (x * (rho - z) - y);
zz = z + h * (x * y - (beta * z));
points->InsertNextPoint(xx, yy, zz);
x = xx;
y = yy;
z = zz;
}
vtkNew<vtkPolyData> pointsPolydata;
pointsPolydata->SetPoints(points);
vtkNew<vtkVertexGlyphFilter> vertexFilter;
vertexFilter->SetInputData(pointsPolydata);
vertexFilter->Update();
vtkProgrammableSource* ps = static_cast<vtkProgrammableSource*>(arg);
vtkPolyData* output = ps->GetPolyDataOutput();
output->DeepCopy(vertexFilter->GetOutput());
}

int main(int, char*[])
{
vtkNew<vtkNamedColors> colors;

vtkNew<vtkProgrammableSource> source;
source->SetExecuteMethod(Lorenz, source);
source->Update();

vtkNew<vtkPolyDataMapper> mapper;
mapper->SetInputData(source->GetPolyDataOutput());

vtkNew<vtkActor> actor;
actor->SetMapper(mapper);
actor->GetProperty()->SetColor(colors->GetColor3d("RosyBrown").GetData());

// Setup render window, renderer, and interactor
vtkNew<vtkRenderer> renderer;
vtkNew<vtkRenderWindow> renderWindow;
vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
renderWindowInteractor->SetRenderWindow(renderWindow);
renderer->SetBackground(colors->GetColor3d("SteelBlue").GetData());

renderWindow->SetWindowName("ProgrammableSource");
renderWindow->Render();
renderWindowInteractor->Start();

return EXIT_SUCCESS;
}


### CMakeLists.txt¶

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(ProgrammableSource)

find_package(VTK COMPONENTS
CommonColor
CommonCore
CommonDataModel
FiltersGeneral
InteractionStyle
RenderingContextOpenGL2
RenderingCore
RenderingFreeType
RenderingGL2PSOpenGL2
RenderingOpenGL2
)

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


cd ProgrammableSource/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:

./ProgrammableSource


WINDOWS USERS

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