### Author:  [@ben.boeckel](https://discourse.vtk.org/u/ben.boeckel)
#### Post date: [October 18, 2022, 12:24am UTC](https://discourse.vtk.org/t/cmake-fetchcontent-build-misses-vtkcommondatamodelmodule-h/9618/6 "2022-10-18T00:24:27Z")
What is making the file in `vtkCommonDataModel` in the first place? It should be in a `DataModel` directory.
---
### Author:  [@drpeterfranz](https://discourse.vtk.org/u/drpeterfranz)
#### Post date: [October 18, 2022, 12:35am UTC](https://discourse.vtk.org/t/cmake-fetchcontent-build-misses-vtkcommondatamodelmodule-h/9618/7 "2022-10-18T00:35:04Z")
The filename is defined in `/CMake/vtkModule.cmake`:
```auto
set(_vtk_add_module_module_header_name
"${_vtk_add_module_library_name}Module.h")
if (NOT _vtk_add_module_HEADER_ONLY AND NOT _vtk_add_module_third_party)
set(_vtk_add_module_generated_header
"${CMAKE_CURRENT_BINARY_DIR}/${_vtk_add_module_module_header_name}")
list(APPEND _vtk_add_module_HEADERS
"${_vtk_add_module_generated_header}")
endif ()
```
The header name is correct, and `${CMAKE_CURRENT_BINARY_DIR}` points to `vtkCommonDataModel` at this point (tested via printing it out).
---
### Author:  [@ben.boeckel](https://discourse.vtk.org/u/ben.boeckel)
#### Post date: [October 18, 2022, 12:47am UTC](https://discourse.vtk.org/t/cmake-fetchcontent-build-misses-vtkcommondatamodelmodule-h/9618/8 "2022-10-18T00:47:12Z")
Why? How are you building VTK that this gets messed up? I’ll note that VTK is _not_ meant to be built by `add_subdirectory`. If you want to vendor it, vendor it like ParaView does (see [its `CMakeLists.txt`](https://gitlab.kitware.com/paraview/paraview/-/blob/master/CMakeLists.txt) for the nitty-gritty details).
---
### Author:  [@drpeterfranz](https://discourse.vtk.org/u/drpeterfranz)
#### Post date: [October 18, 2022, 1:33am UTC](https://discourse.vtk.org/t/cmake-fetchcontent-build-misses-vtkcommondatamodelmodule-h/9618/9 "2022-10-18T01:33:17Z")
Not sure what I muck up, that’s the question lol
I have a complicated chain of dependencies for my project, and I want to be able to build them automatically all in one go, one after the other. Therefore I am setting them all up as _independent_ CMakeProjects, where each project contains a CMakeLists.txt which defines how the project will be built.
In short my VTK project looks like this:
```auto
project(vtk-fss)
FetchContent_Declare(
vtkrepo
GIT_REPOSITORY https://gitlab.kitware.com/vtk/vtk.git
GIT_TAG xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
)
FetchContent_GetProperties(vtkrepo)
if(NOT vtkrepo_POPULATED)
# Fetch the content using previously declared details
FetchContent_Populate(vtkrepo)
set(CMAKE_PROJECT_NAME VTK)
...
set(VTK_MODULE_ENABLE_VTK_eigen YES CACHE BOOL "override" FORCE)
set(VTK_MODULE_ENABLE_VTK_GeovisCore YES CACHE BOOL "override" FORCE)
...
add_subdirectory(${vtkrepo_SOURCE_DIR} ${vtkrepo_BINARY_DIR})
endif()
```
If you have a better idea on how to automate this step, i.e. building it from scratch from a particular git tag and being able to modify CMake variables please let me know.
---
### Author:  [@mwestphal](https://discourse.vtk.org/u/mwestphal)
#### Post date: [October 18, 2022, 1:34am UTC](https://discourse.vtk.org/t/cmake-fetchcontent-build-misses-vtkcommondatamodelmodule-h/9618/10 "2022-10-18T01:34:39Z")
The superbuild is a solution, take a look at the one for ParaView: [https://gitlab.kitware.com/paraview/paraview-superbuild/](https://gitlab.kitware.com/paraview/paraview-superbuild/)
---
### Author:  [@ben.boeckel](https://discourse.vtk.org/u/ben.boeckel)
#### Post date: [October 18, 2022, 1:41pm UTC](https://discourse.vtk.org/t/cmake-fetchcontent-build-misses-vtkcommondatamodelmodule-h/9618/11 "2022-10-18T13:41:59Z")
> [@drpeterfranz](#):
>
> ```auto
> add_subdirectory(${vtkrepo_SOURCE_DIR} ${vtkrepo_BINARY_DIR})
>
> ```
This is what I referred to as “VTK doesn’t support being used through `add_subdirectory`”. Either vendor like ParaView does or build it separately.
---
### Author:  [@drpeterfranz](https://discourse.vtk.org/u/drpeterfranz)
#### Post date: [October 18, 2022, 4:34pm UTC](https://discourse.vtk.org/t/cmake-fetchcontent-build-misses-vtkcommondatamodelmodule-h/9618/12 "2022-10-18T16:34:22Z")
Big sigh.
Thanks guys, I will look into alternative solutions.
It would be great if you add a section to
[https://vtk.org/Wiki/VTK/Configure\_and\_Build](https://vtk.org/Wiki/VTK/Configure_and_Build)
about how to include VTK as a subproject using a minimalistic example.
---
### Author:  [@ben.boeckel](https://discourse.vtk.org/u/ben.boeckel)
#### Post date: [October 18, 2022, 7:49pm UTC](https://discourse.vtk.org/t/cmake-fetchcontent-build-misses-vtkcommondatamodelmodule-h/9618/13 "2022-10-18T19:49:45Z")
It wiki needs a deep clean of old crufy information. The build docs now live in [the repo](https://gitlab.kitware.com/vtk/vtk/-/blob/master/Documentation/dev/build.md). Vendoring is not something that is 100% supported explicitly or in any stable way (global variables expected to exist or files to include change without much notification). ParaView does it because when we bump VTK we keep it in sync. Note that VTK also does not care about the binary directory you give it; it uses `${CMAKE_BINARY_DIR}` for artifacts without a way to override it.
The only road to the supported way is `vtk_module_scan` and `vtk_module_build` VTK’s modules yourself.
---
### Author:  [@drpeterfranz](https://discourse.vtk.org/u/drpeterfranz)
#### Post date: [October 18, 2022, 8:31pm UTC](https://discourse.vtk.org/t/cmake-fetchcontent-build-misses-vtkcommondatamodelmodule-h/9618/14 "2022-10-18T20:31:39Z")
Agree on better build documentation 🙂
Sorry to have wasted your time on this.
---
### Author:  [@drpeterfranz](https://discourse.vtk.org/u/drpeterfranz)
#### Post date: [October 18, 2022, 9:56pm UTC](https://discourse.vtk.org/t/cmake-fetchcontent-build-misses-vtkcommondatamodelmodule-h/9618/15 "2022-10-18T21:56:47Z")
I think I have found a workable solution:
- use cmake’s `FetchContent()` to populate a directory in the build tree containing the source of `VTK`
- use `configure_file()` to configure a file containing the initial cache variables, i.e. which modules to build, where to find `gdal` etc
- create a custom target which configures the `CMakeLists.txt` file found directly in the download location from `FetchContent()` similar to this example:
```auto
add_custom_target(${DEP} ALL
COMMAND ${CMAKE_COMMAND} -S "${DEP_OPTIONS_SOURCE_DIR}" -B . -G "${CMAKE_GENERATOR}" -C "${DEP_OPTIONS_INITIAL_CACHE}" -DCMAKE_BUILD_TYPE="${CMAKE_BUILD_TYPE}" -DCMAKE_CXX_COMPILER="${CMAKE_CXX_COMPILER}" -DCMAKE_C_COMPILER="${CMAKE_C_COMPILER}" -DCMAKE_INSTALL_PREFIX="${DEP_INSTALL_DIR}" -DCMAKE_PREFIX_PATH="${CMAKE_PREFIX_PATH}" -DQT_ROOT_DIR="${QT_ROOT_DIR}" -DQT_BASE_VERSION="${QT_BASE_VERSION}"
COMMAND ${CMAKE_COMMAND} --build . -j
COMMAND ${CMAKE_COMMAND} --install .
DEPENDS ${DEP_OPTIONS_DEPENDS}
WORKING_DIRECTORY ${DEP_BUILD_DIR}
USES_TERMINAL
)
```
This does it for me now, I’m happy 🙂