BozoShaderDemo

VTKExamples/Cxx/Shaders/BozoShaderDemo


Code

BozoShaderDemo.cxx

#include <vtkActor.h>
#include <vtkActor2D.h>
#include <vtkCamera.h>
#include <vtkNamedColors.h>
#include <vtkOpenGLPolyDataMapper.h>
#include <vtkPolyDataNormals.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkShaderProgram.h>
#include <vtkSmartPointer.h>
#include <vtkTextMapper.h>
#include <vtkTextProperty.h>
#include <vtkTransform.h>
#include <vtkTransformPolyDataFilter.h>
#include <vtkTriangleFilter.h>
#include <vtkTriangleMeshPointNormals.h>
#include <vtkVersion.h>

#include <vtkBYUReader.h>
#include <vtkOBJReader.h>
#include <vtkPLYReader.h>
#include <vtkPolyDataReader.h>
#include <vtkSTLReader.h>
#include <vtkSphereSource.h>
#include <vtkXMLPolyDataReader.h>
#include <vtksys/SystemTools.hxx>

#if VTK_VERSION_NUMBER >= 89000000000ULL
#define USE_SHADER_PROPERTIES 1
#include <vtkShaderProperty.h>
#endif

#include <fstream>
#include <sstream>

namespace {
// -----------------------------------------------------------------------
// Update a uniform in the shader for each render. We do this with a
// callback for the UpdateShaderEvent
class vtkShaderCallback : public vtkCommand
{
public:
  static vtkShaderCallback* New()
  {
    return new vtkShaderCallback;
  }
  vtkRenderer* Renderer;
  float k;
  void Execute(vtkObject*, unsigned long, void* calldata) override
  {
    vtkShaderProgram* program = reinterpret_cast<vtkShaderProgram*>(calldata);
    if (program)
    {
      program->SetUniformf("k", k);
    }
  }
  void Print(std::ostream& os)
  {
    os << "k: " << k << std::endl;
  }

  vtkShaderCallback()
  {
    this->Renderer = nullptr;
    this->k = 5;
  }
};
} // namespace

namespace {
vtkSmartPointer<vtkPolyData> ReadPolyData(const char* fileName);
}

//----------------------------------------------------------------------------
int main(int argc, char* argv[])
{
  if (argc < 2)
  {
    std::cout << "Usage: " << argv[0] << " PerlnNoise.glsl "
              << "[polydataFile] "
              << "[k(5)]" << std::endl;
    return EXIT_FAILURE;
  }
  auto colors = vtkSmartPointer<vtkNamedColors>::New();

  auto renderWindow = vtkSmartPointer<vtkRenderWindow>::New();

  // Create one text property for all
  auto textProperty = vtkSmartPointer<vtkTextProperty>::New();
  textProperty->SetFontSize(20);
  //  textProperty->SetJustificationToCentered();
  textProperty->SetColor(0.3, 0.3, 0.3);

  std::vector<vtkSmartPointer<vtkRenderer>> renderers;
  for (int i = 2; i < argc; ++i)
  {
    std::cout << "Reading file: " << argv[i] << std::endl;
    auto polyData = ReadPolyData(argv[i]);
    std::ifstream shaderFile(argv[1]);
    std::ostringstream shaderCode;
    shaderCode << shaderFile.rdbuf();
    shaderFile.close();

    // Create a transform to rescale model
    double center[3];
    polyData->GetCenter(center);
    double bounds[6];
    polyData->GetBounds(bounds);
    double maxBound =
        std::max(std::max(bounds[1] - bounds[0], bounds[3] - bounds[2]),
                 bounds[5] - bounds[4]);

    // Create textActors
    auto textMapper = vtkSmartPointer<vtkTextMapper>::New();
    textMapper->SetTextProperty(textProperty);
    textMapper->SetInput(vtksys::SystemTools::GetFilenameName(argv[i]).c_str());

    auto textActor = vtkSmartPointer<vtkActor2D>::New();
    textActor->SetMapper(textMapper);
    textActor->SetPosition(20, 20);

    auto actor = vtkSmartPointer<vtkActor>::New();
    auto renderer = vtkSmartPointer<vtkRenderer>::New();
    auto mapper = vtkSmartPointer<vtkOpenGLPolyDataMapper>::New();
    renderer->SetBackground(colors->GetColor3d("Burlywood").GetData());

    renderers.push_back(renderer);
    renderWindow->AddRenderer(renderer);
    renderer->AddActor(actor);
    renderer->AddActor(textActor);

    // Rescale polydata to [-1,1]
    auto userTransform = vtkSmartPointer<vtkTransform>::New();
    userTransform->Translate(-center[0], -center[1], -center[2]);
    userTransform->Scale(1.0 / maxBound, 1.0 / maxBound, 1.0 / maxBound);
    auto transform = vtkSmartPointer<vtkTransformPolyDataFilter>::New();
    transform->SetTransform(userTransform);
    transform->SetInputData(polyData);

    auto triangles = vtkSmartPointer<vtkTriangleFilter>::New();
    triangles->SetInputConnection(transform->GetOutputPort());

    auto norms = vtkSmartPointer<vtkTriangleMeshPointNormals>::New();
    norms->SetInputConnection(triangles->GetOutputPort());

    mapper->SetInputConnection(norms->GetOutputPort());
    mapper->ScalarVisibilityOff();

    actor->SetMapper(mapper);
    actor->GetProperty()->SetAmbientColor(0.2, 0.2, 0.2);
    actor->GetProperty()->SetDiffuseColor(1.0, 1.0, 1.0);
    actor->GetProperty()->SetSpecularColor(1.0, 1.0, 1.0);
    actor->GetProperty()->SetSpecular(0.5);
    actor->GetProperty()->SetDiffuse(0.7);
    actor->GetProperty()->SetAmbient(0.1);
    actor->GetProperty()->SetSpecularPower(100.0);
    actor->GetProperty()->SetOpacity(1.0);

    renderer->ResetCamera();
    renderer->GetActiveCamera()->Zoom(1.2);

    // Modify the vertex shader to pass the position of the vertex
#if USE_SHADER_PROPERTIES
    vtkShaderProperty* sp = actor->GetShaderProperty();
    sp->AddVertexShaderReplacement(
        "//VTK::Normal::Dec",  // replace the normal block
        true,                  // before the standard replacements
        "//VTK::Normal::Dec\n" // we still want the default
        "  out vec4 myVertexMC;\n",
        false // only do it once
    );
#else
    mapper->AddShaderReplacement(
        vtkShader::Vertex,
        "//VTK::Normal::Dec",  // replace the normal block
        true,                  // before the standard replacements
        "//VTK::Normal::Dec\n" // we still want the default
        "  out vec4 myVertexMC;\n",
        false // only do it once
    );
#endif
#if USE_SHADER_PROPERTIES
    sp->AddVertexShaderReplacement(
        "//VTK::Normal::Impl",  // replace the normal block
        true,                   // before the standard replacements
        "//VTK::Normal::Impl\n" // we still want the default
        "  myVertexMC = vertexMC;\n",
        false // only do it once
    );

#else
    mapper->AddShaderReplacement(
        vtkShader::Vertex,
        "//VTK::Normal::Impl",  // replace the normal block
        true,                   // before the standard replacements
        "//VTK::Normal::Impl\n" // we still want the default
        "  myVertexMC = vertexMC;\n",
        false // only do it once
    );

#endif
    // Add the code to generate noise
    // These functions need to be defined outside of main. Use the System::Dec
    // to declare and implement
#if USE_SHADER_PROPERTIES
    sp->AddFragmentShaderReplacement("//VTK::System::Dec",
                                     false, // before the standard replacements
                                     shaderCode.str(),
                                     false // only do it once
    );
#else
    mapper->AddShaderReplacement(vtkShader::Fragment, "//VTK::System::Dec",
                                 false, // before the standard replacements
                                 shaderCode.str(),
                                 false // only do it once
    );
#endif

    // Define varying and uniforms for the fragment shader here
#if USE_SHADER_PROPERTIES
    sp->AddFragmentShaderReplacement(
        "//VTK::Normal::Dec",  // replace the normal block
        true,                  // before the standard replacements
        "//VTK::Normal::Dec\n" // we still want the default
        "  varying vec4 myVertexMC;\n"
        "  uniform float k = 1.0;\n",
        false // only do it once
    );
#else
    mapper->AddShaderReplacement(
        vtkShader::Fragment,   // in the fragment shader
        "//VTK::Normal::Dec",  // replace the normal block
        true,                  // before the standard replacements
        "//VTK::Normal::Dec\n" // we still want the default
        "  varying vec4 myVertexMC;\n"
        "  uniform float k = 1.0;\n",
        false // only do it once
    );
#endif

#if USE_SHADER_PROPERTIES
    sp->AddFragmentShaderReplacement(
        "//VTK::Light::Impl",  // replace the light block
        false,                 // after the standard replacements
        "//VTK::Light::Impl\n" // we still want the default calc
        "#define pnoise(x) ((noise(x) + 1.0) / 2.0)\n"
        "  vec3 noisyColor;\n"
        "  noisyColor.r = noise(k * 10.0 * myVertexMC);\n"
        "  noisyColor.g = noise(k * 11.0 * myVertexMC);\n"
        "  noisyColor.b = noise(k * 12.0 * myVertexMC);\n"
        "  /* map ranges of noise values into different colors */\n"
        "  int i;\n"
        "  float lowerValue = .3;\n"
        "  float upperValue = .6;\n"
        "  for ( i=0; i<3; i+=1)\n"
        "  {\n"
        "    noisyColor[i] = (noisyColor[i] + 1.0) / 2.0;\n"
        "    if (noisyColor[i] < lowerValue) \n"
        "    {\n"
        "      noisyColor[i] = lowerValue;\n"
        "    }\n"
        "    else\n"
        "    {\n"
        "      if (noisyColor[i] < upperValue)\n"
        "      {\n"
        "        noisyColor[i] = upperValue;\n"
        "      }\n"
        "      else\n"
        "      {\n"
        "        noisyColor[i] = 1.0;\n"
        "      }\n"
        "    }\n"
        "  }\n"
        "  fragOutput0.rgb = opacity * vec3(ambientColor + noisyColor * "
        "diffuse + specular);\n"
        "  fragOutput0.a = opacity;\n",
        false // only do it once
    );
#else
    mapper->AddShaderReplacement(
        vtkShader::Fragment,   // in the fragment shader
        "//VTK::Light::Impl",  // replace the light block
        false,                 // after the standard replacements
        "//VTK::Light::Impl\n" // we still want the default calc
        "#define pnoise(x) ((noise(x) + 1.0) / 2.0)\n"
        "  vec3 noisyColor;\n"
        "  noisyColor.r = noise(k * 10.0 * myVertexMC);\n"
        "  noisyColor.g = noise(k * 11.0 * myVertexMC);\n"
        "  noisyColor.b = noise(k * 12.0 * myVertexMC);\n"
        "  /* map ranges of noise values into different colors */\n"
        "  int i;\n"
        "  float lowerValue = .3;\n"
        "  float upperValue = .6;\n"
        "  for ( i=0; i<3; i+=1)\n"
        "  {\n"
        "    noisyColor[i] = (noisyColor[i] + 1.0) / 2.0;\n"
        "    if (noisyColor[i] < lowerValue) \n"
        "    {\n"
        "      noisyColor[i] = lowerValue;\n"
        "    }\n"
        "    else\n"
        "    {\n"
        "      if (noisyColor[i] < upperValue)\n"
        "      {\n"
        "        noisyColor[i] = upperValue;\n"
        "      }\n"
        "      else\n"
        "      {\n"
        "        noisyColor[i] = 1.0;\n"
        "      }\n"
        "    }\n"
        "  }\n"
        "  fragOutput0.rgb = opacity * vec3(ambientColor + noisyColor * "
        "diffuse + specular);\n"
        "  fragOutput0.a = opacity;\n",
        false // only do it once
    );
#endif
    auto myCallback = vtkSmartPointer<vtkShaderCallback>::New();
    myCallback->Renderer = renderer;
    myCallback->k = 1;
    mapper->AddObserver(vtkCommand::UpdateShaderEvent, myCallback);
  }

  // Setup viewports for the renderers
  int rendererSize = 250;
  unsigned int xGridDimensions = 3;
  unsigned int yGridDimensions = 3;
  renderWindow->SetSize(rendererSize * xGridDimensions,
                        rendererSize * yGridDimensions);
  for (int row = 0; row < static_cast<int>(yGridDimensions); row++)
  {
    for (int col = 0; col < static_cast<int>(xGridDimensions); col++)
    {
      int index = row * xGridDimensions + col;
      // (xmin, ymin, xmax, ymax)
      double viewport[4] = {static_cast<double>(col) * rendererSize /
                                (xGridDimensions * rendererSize),
                            static_cast<double>(yGridDimensions - (row + 1)) *
                                rendererSize / (yGridDimensions * rendererSize),
                            static_cast<double>(col + 1) * rendererSize /
                                (xGridDimensions * rendererSize),
                            static_cast<double>(yGridDimensions - row) *
                                rendererSize /
                                (yGridDimensions * rendererSize)};
      renderers[index]->SetViewport(viewport);
    }
  }

  auto interactor = vtkSmartPointer<vtkRenderWindowInteractor>::New();
  interactor->SetRenderWindow(renderWindow);

  renderWindow->Render();
  renderWindow->SetWindowName("BozoShaderDemo");
  renderWindow->Render();
  interactor->Start();

  return EXIT_SUCCESS;
}

namespace {
vtkSmartPointer<vtkPolyData> ReadPolyData(const char* fileName)
{
  vtkSmartPointer<vtkPolyData> polyData;
  std::string extension =
      vtksys::SystemTools::GetFilenameExtension(std::string(fileName));
  if (extension == ".ply")
  {
    auto reader = vtkSmartPointer<vtkPLYReader>::New();
    reader->SetFileName(fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".vtp")
  {
    auto reader = vtkSmartPointer<vtkXMLPolyDataReader>::New();
    reader->SetFileName(fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".obj")
  {
    auto reader = vtkSmartPointer<vtkOBJReader>::New();
    reader->SetFileName(fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".stl")
  {
    auto reader = vtkSmartPointer<vtkSTLReader>::New();
    reader->SetFileName(fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".vtk")
  {
    auto reader = vtkSmartPointer<vtkPolyDataReader>::New();
    reader->SetFileName(fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".g")
  {
    auto reader = vtkSmartPointer<vtkBYUReader>::New();
    reader->SetGeometryFileName(fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else
  {
    auto source = vtkSmartPointer<vtkSphereSource>::New();
    source->SetPhiResolution(25);
    source->SetThetaResolution(25);
    source->Update();
    polyData = source->GetOutput();
  }
  return polyData;
}
} // namespace

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(BozoShaderDemo)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkCommonTransforms
  vtkFiltersCore
  vtkFiltersGeneral
  vtkFiltersSources
  vtkIOGeometry
  vtkIOLegacy
  vtkIOPLY
  vtkIOXML
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping BozoShaderDemo: ${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(BozoShaderDemo MACOSX_BUNDLE BozoShaderDemo.cxx )
  target_link_libraries(BozoShaderDemo PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(BozoShaderDemo MACOSX_BUNDLE BozoShaderDemo.cxx )
  target_link_libraries(BozoShaderDemo PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS BozoShaderDemo
    MODULES ${VTK_LIBRARIES}
    )
endif () 

Download and Build BozoShaderDemo

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

cd BozoShaderDemo/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:

./BozoShaderDemo

WINDOWS USERS

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