BozoShaderDemo

VTKExamples/Cxx/Shaders/BozoShaderDemo


Code

BozoShaderDemo.cxx

#include <vtkSmartPointer.h>

#include <vtkCamera.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkShaderProgram.h>
#include <vtkActor.h>
#include <vtkActor2D.h>
#include <vtkOpenGLPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkPolyDataNormals.h>
#include <vtkTextProperty.h>
#include <vtkTextMapper.h>

#include <vtkTransform.h>
#include <vtkTransformPolyDataFilter.h>
#include <vtkTriangleMeshPointNormals.h>
#include <vtkTriangleFilter.h>

#include <vtkNamedColors.h>
#include <vtkRenderWindowInteractor.h>

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

#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
{
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;
  }
  vtkSmartPointer<vtkNamedColors> colors =
    vtkSmartPointer<vtkNamedColors>::New();

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

  // Create one text property for all
  vtkSmartPointer<vtkTextProperty> 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;
    vtkSmartPointer<vtkPolyData> 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
    vtkSmartPointer<vtkTextMapper> textMapper =
      vtkSmartPointer<vtkTextMapper>::New();
    textMapper->SetTextProperty(textProperty);
    textMapper->SetInput(vtksys::SystemTools::GetFilenameName(argv[i]).c_str());

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

    vtkSmartPointer<vtkActor> actor =
      vtkSmartPointer<vtkActor>::New();
    vtkSmartPointer<vtkRenderer> renderer =
      vtkSmartPointer<vtkRenderer>::New();
    vtkSmartPointer<vtkOpenGLPolyDataMapper> 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]
  vtkSmartPointer<vtkTransform> userTransform =
    vtkSmartPointer<vtkTransform>::New();
  userTransform->Translate(-center[0], -center[1], -center[2]);
  userTransform->Scale(1.0/maxBound, 1.0/maxBound, 1.0/maxBound);
  vtkSmartPointer<vtkTransformPolyDataFilter> transform =
    vtkSmartPointer<vtkTransformPolyDataFilter>::New();
  transform->SetTransform(userTransform);
  transform->SetInputData(polyData);

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

  vtkSmartPointer<vtkTriangleMeshPointNormals> 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
  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
    );
  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
    );

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

  // Define varying and uniforms for the fragment shader here
  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
    );

  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
    );
  vtkSmartPointer<vtkShaderCallback> 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);
    }
  }

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

  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")
  {
    vtkSmartPointer<vtkPLYReader> reader =
      vtkSmartPointer<vtkPLYReader>::New();
    reader->SetFileName (fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".vtp")
  {
    vtkSmartPointer<vtkXMLPolyDataReader> reader =
      vtkSmartPointer<vtkXMLPolyDataReader>::New();
    reader->SetFileName (fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".obj")
  {
    vtkSmartPointer<vtkOBJReader> reader =
      vtkSmartPointer<vtkOBJReader>::New();
    reader->SetFileName (fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".stl")
  {
    vtkSmartPointer<vtkSTLReader> reader =
      vtkSmartPointer<vtkSTLReader>::New();
    reader->SetFileName (fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".vtk")
  {
    vtkSmartPointer<vtkPolyDataReader> reader =
      vtkSmartPointer<vtkPolyDataReader>::New();
    reader->SetFileName (fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".g")
  {
    vtkSmartPointer<vtkBYUReader> reader =
      vtkSmartPointer<vtkBYUReader>::New();
    reader->SetGeometryFileName (fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else
  {
    vtkSmartPointer<vtkSphereSource> source =
      vtkSmartPointer<vtkSphereSource>::New();
    source->SetPhiResolution(25);
    source->SetThetaResolution(25);
    source->Update();
    polyData = source->GetOutput();
  }
  return polyData;
}
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(BozoShaderDemo)

find_package(VTK REQUIRED)
include(${VTK_USE_FILE})

add_executable(BozoShaderDemo MACOSX_BUNDLE BozoShaderDemo.cxx )

target_link_libraries(BozoShaderDemo ${VTK_LIBRARIES})

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.