VTK/VTK 6 Migration/Factories now require defines
"I've done all this, it compiles and links, but now "New()" returns NULL at runtime"
If you build your project with CMake, and you use the standard find_package(VTK) and include(${VTK_USE_FILE}) then this problem should not occur. (Because the defines will be automatically added for you by virtue of the include(${VTK_USE_FILE})...) Consider following the guide to using implementation modules, which has fuller details on using implementation modules without using CMake if your project demands it.
The factory methods now require "auto-initialization" depending on what modules are enabled at VTK configure time. If you are enabling all modules, and building your project without using CMake, you will need some defines in your project in order to make the factories work properly.
On September 10, 2013 a new macro was added to make this process a little simpler for projects that just want to initialize modules, where ordering ceases to be important but you must still build a source file into your application that has something along with following (with one entry for each module that should be initialized).
#include <vtkAutoInit.h> VTK_MODULE_INIT(vtkRenderingOpenGL);
This will initialize the vtkRenderingOpenGL object factories, and should be done for each module. If you are using an older version of VTK (6.0 or master from before the date above) than you can try including this snippet in all your code that includes VTK usage, BEFORE including ANY VTK header files:
#define vtkRenderingCore_AUTOINIT 4(vtkInteractionStyle,vtkRenderingFreeType,vtkRenderingFreeTypeOpenGL,vtkRenderingOpenGL) #define vtkRenderingVolume_AUTOINIT 1(vtkRenderingVolumeOpenGL)
See these references (and follow the mailing list threads to their conclusions) for more info:
- http://www.vtk.org/pipermail/vtkusers/2013-April/128255.html
- https://github.com/Kitware/VTK/commit/9385718b82e6af83b7e7dcc90a937419edc6892b
- http://www.vtk.org/pipermail/vtkusers/2013-March/127811.html
I have also had the NULL pointer; surely the code should not compile and just dump a NULL pointer as a result of a call to
theMapper = vtkPolyDataMapper::New();
However after setting the above options (in Windows VStudio 2008 v9 "Property Pages->Preprocessor definitions" for the program I am linking) I get a message from my compiler that some (20) functions were not found. The user at ref [1] seems to have hundreds of missing links.
"2>vtkSDIView.obj : error LNK2001: unresolved external symbol "void __cdecl vtkInteractionStyle_AutoInit_Construct(void)" (?vtkInteractionStyle_AutoInit_Construct@@YAXXZ) 2>vtkSDI.cpp.obj : error LNK2001: unresolved external symbol "void __cdecl vtkInteractionStyle_AutoInit_Destruct(void)"(?vtkInteractionStyle_AutoInit_Destruct@@YAXXZ)"
After linking all the libraries found in the example code (eg the Cone example) these link errors go away. This required adding several tens of new libraries that I had not needed to link for version 5.8 which is slightly annoying. The preprocessor definitions I mention above can also be copied from the Cone example.
