add opengl gpu image processing support

Provide an example of how to use the GPU to
do some image processing. Includes a helper class
that handles some of the common tasks that you would
need to do for image processing.

Imaging/OpenGL2/CMakeLists.txt

+set(Module_SRCS
+  vtkOpenGLImageGradient.cxx
+  )
+
+vtk_module_library(${vtk-module} ${Module_SRCS})

Imaging/OpenGL2/Testing/Cxx/CMakeLists.txt

+vtk_add_test_cxx(${vtk-module}CxxTests tests
+  TestOpenGLImageGradient.cxx
+  )
+
+vtk_test_cxx_executable(${vtk-module}CxxTests tests RENDERING_FACTORY)

Imaging/OpenGL2/Testing/Cxx/TestOpenGLImageGradient.cxx

+/*=========================================================================
+
+  Program:   Visualization Toolkit
+
+  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
+  All rights reserved.
+  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
+
+     This software is distributed WITHOUT ANY WARRANTY; without even
+     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+     PURPOSE.  See the above copyright notice for more information.
+
+=========================================================================*/
+
+#include "vtkNew.h"
+
+#include "vtkRenderWindowInteractor.h"
+#include "vtkInteractorStyleImage.h"
+#include "vtkRenderWindow.h"
+#include "vtkRenderer.h"
+#include "vtkCamera.h"
+#include "vtkImageData.h"
+#include "vtkImageSliceMapper.h"
+#include "vtkImageProperty.h"
+#include "vtkImageSlice.h"
+#include "vtkImageReader2.h"
+#include "vtkOpenGLImageGradient.h"
+#include "vtkPointData.h"
+#include "vtkDataArray.h"
+
+#include "vtkTestUtilities.h"
+#include "vtkRegressionTestImage.h"
+
+int TestOpenGLImageGradient(int argc, char *argv[])
+{
+  vtkNew<vtkRenderWindowInteractor> iren;
+  vtkNew<vtkInteractorStyleImage> style;
+  style->SetInteractionModeToImageSlicing();
+  vtkNew<vtkRenderWindow> renWin;
+  iren->SetRenderWindow(renWin.Get());
+  iren->SetInteractorStyle(style.Get());
+
+  char* fname =
+    vtkTestUtilities::ExpandDataFileName(argc, argv, "Data/headsq/quarter");
+
+  vtkNew<vtkImageReader2> reader;
+  reader->SetDataByteOrderToLittleEndian();
+  reader->SetDataExtent(0,63,0,63,1,93);
+  reader->SetDataSpacing(3.2, 3.2, 1.5);
+  reader->SetFilePrefix(fname);
+
+  delete [] fname;
+
+  vtkNew<vtkOpenGLImageGradient> filter;
+  //  vtkNew<vtkImageGradient> filter;
+  filter->SetInputConnection(reader->GetOutputPort());
+  filter->Update();
+  // double *rnger = filter->GetOutput()->GetPointData()->GetScalars()->GetRange();
+
+  vtkNew<vtkImageSliceMapper> imageMapper;
+  imageMapper->SetInputConnection(filter->GetOutputPort());
+  imageMapper->SetOrientation(2);
+  imageMapper->SliceAtFocalPointOn();
+
+  vtkNew<vtkImageSlice> image;
+  image->SetMapper(imageMapper.Get());
+
+  double range[2] = { -100, 100 };
+
+  image->GetProperty()->SetColorWindow(range[1] - range[0]);
+  image->GetProperty()->SetColorLevel(0.5*(range[0] + range[1]));
+  image->GetProperty()->SetInterpolationTypeToNearest();
+
+  vtkNew<vtkRenderer> renderer;
+  renderer->AddViewProp(image.Get());
+  renderer->SetBackground(0.2,0.3,0.4);
+  renWin->AddRenderer(renderer.Get());
+
+  double *bounds = imageMapper->GetBounds();
+  double point[3];
+  point[0] = 0.5*(bounds[0] + bounds[1]);
+  point[1] = 0.5*(bounds[2] + bounds[3]);
+  point[2] = 0.5*(bounds[4] + bounds[5]);
+
+  vtkCamera *camera = renderer->GetActiveCamera();
+  camera->SetFocalPoint(point);
+  point[imageMapper->GetOrientation()] += 500.0;
+  camera->SetPosition(point);
+  if (imageMapper->GetOrientation() == 2)
+    {
+    camera->SetViewUp(0.0, 1.0, 0.0);
+    }
+  else
+    {
+    camera->SetViewUp(0.0, 0.0, -1.0);
+    }
+  camera->ParallelProjectionOn();
+  camera->SetParallelScale(0.8*128);
+
+  renWin->SetSize(512,512);
+  iren->Initialize();
+  renWin->Render();
+
+  int retVal = vtkRegressionTestImage( renWin.Get() );
+  if ( retVal == vtkRegressionTester::DO_INTERACTOR)
+    {
+    iren->Start();
+    }
+
+  return !retVal;
+}

Imaging/OpenGL2/Testing/Data/Baseline/TestOpenGLImageGradient.png.md5

+3356e2c0df6349f887a0c520952e9c06

Imaging/OpenGL2/module.cmake

+vtk_module(vtkImagingOpenGL2
+  TCL_NAME vtkImagingOpenGLII
+  BACKEND
+    OpenGL2
+  DEPENDS
+    vtkImagingGeneral
+    vtkRendering${VTK_RENDERING_BACKEND}
+  TEST_DEPENDS
+    vtkTestingRendering
+    vtkInteractionStyle
+)

Imaging/OpenGL2/vtkOpenGLImageGradient.cxx

+/*=========================================================================
+
+  Program:   Visualization Toolkit
+  Module:    vtkOpenGLImageGradient.cxx
+
+  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
+  All rights reserved.
+  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
+
+     This software is distributed WITHOUT ANY WARRANTY; without even
+     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+     PURPOSE.  See the above copyright notice for more information.
+
+=========================================================================*/
+#include "vtkOpenGLImageGradient.h"
+
+#include "vtkOpenGLImageAlgorithmHelper.h"
+
+#include "vtkCellData.h"
+#include "vtkDataArray.h"
+#include "vtkImageData.h"
+#include "vtkInformation.h"
+#include "vtkInformationVector.h"
+#include "vtkObjectFactory.h"
+#include "vtkPointData.h"
+#include "vtkStreamingDemandDrivenPipeline.h"
+#include "vtkShaderProgram.h"
+
+#include <algorithm> // for std::nth_element
+
+vtkStandardNewMacro(vtkOpenGLImageGradient);
+
+//-----------------------------------------------------------------------------
+// Construct an instance of vtkOpenGLImageGradient fitler.
+vtkOpenGLImageGradient::vtkOpenGLImageGradient()
+{
+  // for GPU we do not want threading
+  this->NumberOfThreads = 1;
+  this->EnableSMP = false;
+  this->Helper = vtkOpenGLImageAlgorithmHelper::New();
+}
+
+//-----------------------------------------------------------------------------
+vtkOpenGLImageGradient::~vtkOpenGLImageGradient()
+{
+  if (this->Helper)
+    {
+    this->Helper->Delete();
+    this->Helper = 0;
+    }
+}
+
+void vtkOpenGLImageGradient::SetRenderWindow(vtkRenderWindow *renWin)
+{
+  this->Helper->SetRenderWindow(renWin);
+}
+
+//-----------------------------------------------------------------------------
+void vtkOpenGLImageGradient::PrintSelf(ostream& os, vtkIndent indent)
+{
+  this->Superclass::PrintSelf(os, indent);
+
+  os << indent << "Helper: ";
+  this->Helper->PrintSelf(os, indent);
+}
+
+// this is used as a callback by the helper to set shader parameters
+// before running and to update them on each slice
+class vtkOpenGLGradientCB : public vtkOpenGLImageAlgorithmCallback
+{
+public:
+  // initialize the spacing
+  virtual void InitializeShaderUniforms(vtkShaderProgram *program)
+    {
+    float sp[3];
+    sp[0] = this->Spacing[0];
+    sp[1] = this->Spacing[1];
+    sp[2] = this->Spacing[2];
+    program->SetUniform3f("spacing", sp);
+    }
+
+  // no uniforms change on a per slice basis so empty
+  virtual void UpdateShaderUniforms(
+    vtkShaderProgram * /* program */, int /* zExtent */) {};
+
+  double *Spacing;
+};
+
+//-----------------------------------------------------------------------------
+// This method contains the first switch statement that calls the correct
+// templated function for the input and output region types.
+void vtkOpenGLImageGradient::ThreadedRequestData(
+  vtkInformation *vtkNotUsed(request),
+  vtkInformationVector **inputVector,
+  vtkInformationVector *vtkNotUsed(outputVector),
+  vtkImageData ***inData,
+  vtkImageData **outData,
+  int outExt[6], int vtkNotUsed(id))
+{
+  void *inPtr;
+
+  vtkDataArray *inArray = this->GetInputArrayToProcess(0,inputVector);
+  outData[0]->GetPointData()->GetScalars()->SetName(inArray->GetName());
+
+  inPtr = inArray->GetVoidPointer(0);
+
+  // The ouptut scalar type must be double to store proper gradients.
+  if(outData[0]->GetScalarType() != VTK_DOUBLE)
+    {
+    vtkErrorMacro("Execute: output ScalarType is "
+                  << outData[0]->GetScalarType() << "but must be double.");
+    return;
+    }
+
+  // Gradient makes sense only with one input component.  This is not
+  // a Jacobian filter.
+  if(inArray->GetNumberOfComponents() != 1)
+    {
+    vtkErrorMacro(
+      "Execute: input has more than one component. "
+      "The input to gradient should be a single component image. "
+      "Think about it. If you insist on using a color image then "
+      "run it though RGBToHSV then ExtractComponents to get the V "
+      "components. That's probably what you want anyhow.");
+    return;
+    }
+
+  vtkOpenGLGradientCB cb;
+  cb.Spacing = inData[0][0]->GetSpacing();
+
+  // build the fragement shader for 2D or 3D gradient
+  std::string fragShader =
+    "//VTK::System::Dec\n"
+    "varying vec2 tcoordVSOutput;\n"
+    "uniform sampler3D inputTex1;\n"
+    "uniform float zPos;\n"
+    "uniform vec3 spacing;\n"
+    "uniform float inputScale;\n"
+    "uniform float inputShift;\n"
+    "//VTK::Output::Dec\n"
+    "void main(void) {\n"
+    "  float dx = textureOffset(inputTex1, vec3(tcoordVSOutput, zPos), ivec3(1,0,0)).r\n"
+    "    - textureOffset(inputTex1, vec3(tcoordVSOutput, zPos), ivec3(-1,0,0)).r;\n"
+    "  dx = inputScale*0.5*dx/spacing.x;\n"
+    "  float dy = textureOffset(inputTex1, vec3(tcoordVSOutput, zPos), ivec3(0,1,0)).r\n"
+    "    - textureOffset(inputTex1, vec3(tcoordVSOutput, zPos), ivec3(0,-1,0)).r;\n"
+    "  dy = inputScale*0.5*dy/spacing.y;\n"
+    ;
+
+  if (this->Dimensionality == 3)
+    {
+    fragShader +=
+      "  float dz = textureOffset(inputTex1, vec3(tcoordVSOutput, zPos), ivec3(0,0,1)).r\n"
+      "    - textureOffset(inputTex1, vec3(tcoordVSOutput, zPos), ivec3(0,0,-1)).r;\n"
+      "  dz = inputScale*0.5*dz/spacing.z;\n";
+      "  gl_FragData[0] = vec4(dx, dy, dz, 1.0);\n"
+      "}\n";
+    }
+  else
+    {
+    fragShader +=
+      "  gl_FragData[0] = vec4(dx, dy, 0.0, 1.0);\n"
+      "}\n";
+    }
+
+  // call the helper to execte this code
+  this->Helper->Execute(&cb,
+    inData[0][0], inArray,
+    outData[0], outExt,
+
+    "//VTK::System::Dec\n"
+    "attribute vec4 vertexMC;\n"
+    "attribute vec2 tcoordMC;\n"
+    "varying vec2 tcoordVSOutput;\n"
+    "void main() {\n"
+    "  tcoordVSOutput = tcoordMC;\n"
+    "  gl_Position = vertexMC;\n"
+    "}\n",
+
+    fragShader.c_str(),
+
+    "");
+}

Imaging/OpenGL2/vtkOpenGLImageGradient.h

+/*=========================================================================
+
+  Program:   Visualization Toolkit
+  Module:    vtkOpenGLImageGradient.h
+
+  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
+  All rights reserved.
+  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
+
+     This software is distributed WITHOUT ANY WARRANTY; without even
+     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+     PURPOSE.  See the above copyright notice for more information.
+
+=========================================================================*/
+// .NAME vtkOpenGLImageGradient - Compute Gradient using the GPU
+
+#ifndef vtkOpenGLImageGradient_h
+#define vtkOpenGLImageGradient_h
+
+#include "vtkImagingOpenGL2Module.h" // For export macro
+#include "vtkImageGradient.h"
+
+class vtkOpenGLImageAlgorithmHelper;
+class vtkRenderWindow;
+
+class VTKIMAGINGOPENGL2_EXPORT vtkOpenGLImageGradient : public vtkImageGradient
+{
+public:
+  static vtkOpenGLImageGradient *New();
+  vtkTypeMacro(vtkOpenGLImageGradient,vtkImageGradient);
+
+  // Description:
+  // Set the render window to get the OpenGL resources from
+  void SetRenderWindow(vtkRenderWindow *);
+
+protected:
+  void PrintSelf(ostream& os, vtkIndent indent);
+  vtkOpenGLImageGradient();
+  ~vtkOpenGLImageGradient();
+
+  vtkOpenGLImageAlgorithmHelper *Helper;
+
+  void ThreadedRequestData(vtkInformation *request,
+                           vtkInformationVector **inputVector,
+                           vtkInformationVector *outputVector,
+                           vtkImageData ***inData, vtkImageData **outData,
+                           int extent[6], int id);
+
+private:
+  vtkOpenGLImageGradient(const vtkOpenGLImageGradient&);  // Not implemented.
+  void operator=(const vtkOpenGLImageGradient&);  // Not implemented.
+};
+
+#endif

Rendering/OpenGL2/CMakeLists.txt

@@ -38,6 +38,7 @@ set(Module_SRCS
   vtkOpenGLGlyph3DMapper.cxx
   vtkOpenGLHardwareSelector.cxx
   vtkOpenGLHelper.cxx
+  vtkOpenGLImageAlgorithmHelper.cxx
   vtkOpenGLImageMapper.cxx
   vtkOpenGLImageSliceMapper.cxx
   vtkOpenGLIndexBufferObject.cxx

Rendering/OpenGL2/vtkOpenGLImageAlgorithmHelper.cxx

+/*=========================================================================
+
+  Program:   Visualization Toolkit
+  Module:    vtkOpenGLImageAlgorithmHelper.cxx
+
+  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
+  All rights reserved.
+  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
+
+     This software is distributed WITHOUT ANY WARRANTY; without even
+     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+     PURPOSE.  See the above copyright notice for more information.
+
+=========================================================================*/
+
+#include "vtkOpenGLImageAlgorithmHelper.h"
+#include "vtkObjectFactory.h"
+#include "vtkTextureObject.h"
+#include "vtkOpenGLRenderWindow.h"
+#include "vtkDataArray.h"
+#include "vtkImageData.h"
+#include "vtkNew.h"
+#include "vtkFrameBufferObject.h"
+#include "vtkOpenGLShaderCache.h"
+#include "vtk_glew.h"
+#include "vtkPixelTransfer.h"
+#include "vtkPointData.h"
+#include "vtkPixelBufferObject.h"
+#include "vtkShaderProgram.h"
+#include "vtkOpenGLVertexArrayObject.h"
+
+vtkStandardNewMacro(vtkOpenGLImageAlgorithmHelper);
+
+// ----------------------------------------------------------------------------
+vtkOpenGLImageAlgorithmHelper::vtkOpenGLImageAlgorithmHelper()
+{
+  this->RenderWindow = 0;
+}
+
+// ----------------------------------------------------------------------------
+vtkOpenGLImageAlgorithmHelper::~vtkOpenGLImageAlgorithmHelper()
+{
+  this->SetRenderWindow(0);
+}
+
+void vtkOpenGLImageAlgorithmHelper::SetRenderWindow(vtkRenderWindow *renWin)
+{
+  if (renWin == this->RenderWindow.Get())
+    {
+    return;
+    }
+
+  vtkOpenGLRenderWindow *orw  = NULL;
+  if (renWin)
+    {
+    orw = vtkOpenGLRenderWindow::SafeDownCast(renWin);
+    }
+
+  this->RenderWindow = orw;
+  this->Modified();
+}
+
+void vtkOpenGLImageAlgorithmHelper::Execute(
+  vtkOpenGLImageAlgorithmCallback *cb,
+  vtkImageData *inImage, vtkDataArray *inArray,
+  vtkImageData *outImage, int outExt[6],
+  const char *vertexCode,
+  const char *fragmentCode,
+  const char *geometryCode
+  )
+{
+  // make sure it is initialized
+  if (!this->RenderWindow)
+    {
+    this->SetRenderWindow(vtkRenderWindow::New());
+    this->RenderWindow->SetOffScreenRendering(true);
+    this->RenderWindow->UnRegister(this);
+    }
+  this->RenderWindow->Initialize();
+
+  // Is it a 2D or 3D image
+  int dims[3];
+  inImage->GetDimensions(dims);
+  int dimensions = 0;
+  for (int i = 0; i < 3; i ++)
+    {
+    if (dims[i] > 1)
+      {
+      dimensions++;
+      }
+    }
+
+  // no 1d or 2D supprt yet
+  if (dimensions < 3)
+    {
+    vtkErrorMacro("no 1D or 2D processing support yet");
+    return;
+    }
+
+  // send vector data to a texture
+  int inputExt[6];
+  inImage->GetExtent(inputExt);
+  void *inPtr = inArray->GetVoidPointer(0);
+
+  // could do shortcut here if the input volume is
+  // exactly what we want (updateExtent == wholeExtent)
+  // vtkIdType incX, incY, incZ;
+  // inImage->GetContinuousIncrements(inArray, extent, incX, incY, incZ);
+  //  tmpImage->CopyAndCastFrom(inImage, inUpdateExtent)
+
+  vtkNew<vtkTextureObject> inputTex;
+  inputTex->SetContext(this->RenderWindow);
+  inputTex->Create3DFromRaw(
+    dims[0], dims[1], dims[2],
+    inArray->GetNumberOfComponents(),
+    inArray->GetDataType(), inPtr);
+
+  float shift = 0.0;
+  float scale = 1.0;
+  inputTex->GetShiftAndScale(shift, scale);
+
+  // now create the framebuffer for the output
+  int outDims[3];
+  outDims[0] = outExt[1] - outExt[0] + 1;
+  outDims[1] = outExt[3] - outExt[2] + 1;
+  outDims[2] = outExt[5] - outExt[4] + 1;
+
+  vtkNew<vtkTextureObject> outputTex;
+  outputTex->SetContext(this->RenderWindow);
+
+  vtkNew<vtkFrameBufferObject> fbo;
+  fbo->SetContext(this->RenderWindow);
+
+  outputTex->Create2D(outDims[0], outDims[1], 4, VTK_FLOAT, false);
+  fbo->SetNumberOfRenderTargets(1);
+  fbo->SetColorBuffer(0,outputTex.Get());
+
+  // because the same FBO can be used in another pass but with several color
+  // buffers, force this pass to use 1, to avoid side effects from the
+  // render of the previous frame.
+  fbo->SetActiveBuffer(0);
+
+//  fbo->SetDepthBufferNeeded(true);
+  fbo->SetDepthBufferNeeded(false);
+  fbo->StartNonOrtho(outDims[0], outDims[1], false);
+  glViewport(0, 0, outDims[0], outDims[1]);
+  glScissor(0, 0, outDims[0], outDims[1]);
+  glDisable(GL_DEPTH_TEST);
+
+  vtkShaderProgram *prog =
+    this->RenderWindow->GetShaderCache()->ReadyShaderProgram(
+      vertexCode, fragmentCode, geometryCode);
+  if (prog != this->Quad.Program)
+    {
+    this->Quad.Program = prog;
+    this->Quad.VAO->ShaderProgramChanged();
+    }
+  cb->InitializeShaderUniforms(prog);
+
+  inputTex->Activate();
+  int inputTexId = inputTex->GetTextureUnit();
+  this->Quad.Program->SetUniformi("inputTex1", inputTexId);
+  // shift and scale to get the data backing into its original units
+  this->Quad.Program->SetUniformf("inputShift", shift);
+  this->Quad.Program->SetUniformf("inputScale", scale);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+
+  // for each zslice in the output
+  vtkPixelExtent outputPixelExt(outExt);
+  for (int i = outExt[4]; i <= outExt[5]; i++)
+    {
+    cb->UpdateShaderUniforms(prog, i);
+    this->Quad.Program->SetUniformf("zPos", (i - outExt[4] + 0.5) / (outDims[2]));
+
+    fbo->RenderQuad(
+      0, outDims[0] - 1,
+      0, outDims[1] - 1,
+      this->Quad.Program, this->Quad.VAO);
+
+    vtkPixelBufferObject *outPBO = outputTex->Download();
+
+    vtkPixelTransfer::Blit<float, double>(
+      outputPixelExt,
+      outputPixelExt,
+      outputPixelExt,
+      outputPixelExt,
+      4,
+      (float*)outPBO->MapPackedBuffer(),
+      outImage->GetPointData()->GetScalars()->GetNumberOfComponents(),
+      static_cast<double *>(outImage->GetScalarPointer(outExt[0], outExt[2], i)));
+
+    outPBO->UnmapPackedBuffer();
+    outPBO->Delete();
+  }
+}
+
+// ----------------------------------------------------------------------------
+void vtkOpenGLImageAlgorithmHelper::PrintSelf(ostream& os, vtkIndent indent)
+{
+  this->Superclass::PrintSelf(os,indent);
+
+  os << indent << "RenderWindow:";
+  if(this->RenderWindow != 0)
+    {
+    this->RenderWindow->PrintSelf(os,indent);
+    }
+  else
+    {
+    os << "(none)" <<endl;
+    }
+}

Rendering/OpenGL2/vtkOpenGLImageAlgorithmHelper.h

+/*=========================================================================