Method Download

Rendering/OpenGL2/vtkTextureObject.cxx:1461–1506

------------------------------------------------------------------------------

//------------------------------------------------------------------------------
vtkPixelBufferObject* vtkTextureObject::Download(unsigned int target, unsigned int level)
{
  assert(this->Context);
  assert(this->Handle);

  vtkPixelBufferObject* pbo = vtkPixelBufferObject::New();
  pbo->SetContext(this->Context);

  int vtktype = ::vtkGetVTKType(this->Type);
  if (vtktype == 0)
  {
    vtkErrorMacro("Failed to determine type.");
    return nullptr;
  }

  unsigned int size = this->Width * this->Height * this->Depth;

  // doesn't matter which Upload*D method we use since we are not really
  // uploading any data, simply allocating GPU space.
  if (!pbo->Upload1D(vtktype, nullptr, size, this->Components, 0))
  {
    vtkErrorMacro("Could not allocate memory for PBO.");
    pbo->Delete();
    return nullptr;
  }

  pbo->Bind(vtkPixelBufferObject::PACKED_BUFFER);
  this->Bind();

#ifndef GL_ES_VERSION_3_0
  glGetTexImage(target, level, this->Format, this->Type, BUFFER_OFFSET(0));
#else
  (void)level;
  (void)target;
  // you can do something with glReadPixels and binding a texture as a FBO
  // I believe for ES 2.0
#endif

  vtkOpenGLCheckErrorMacro("failed at glGetTexImage");
  this->Deactivate();
  pbo->UnBind();

  pbo->SetComponents(this->Components);

  return pbo;
}

//------------------------------------------------------------------------------
vtkPixelBufferObject* vtkTextureObject::Download()