title: default search paths for CMake include() vs. find_package()
body: <p>I have VTK6 installed on my Debian machine and it places all its CMake files under</p>
  
  <pre><code>$ ls /usr/lib/cmake/vtk-6.3/
  [...]
  VTKConfig.cmake
  vtkModuleAPI.cmake
  [...]
  </code></pre>
  
  <p>When I do</p>
  
  
  
  <pre><code>find_package(VTK)
  </code></pre>
  
  <p>in another project, it all works out fine. However,</p>
  
  
  
  <pre><code>include(vtkModuleAPI)
  </code></pre>
  
  <p>yields the error</p>
  
  <pre><code>include could not find load file:
  
    vtkModuleAPI
  </code></pre>
  
  <p>I had always been under the impression that <code>find_package()</code> and <code>include</code> share the same search paths, specifically <code>CMAKE_MODULE_PATH</code>. Apparently that's not correct.</p>
  
  <p>Note that</p>
  
  
  
  <pre><code>SET(CMAKE_MODULE_PATH "/usr/lib/cmake/vtk-6.3")
  include(vtkModuleAPI)
  </code></pre>
  
  <p>does work.</p>
  
  <p>Also note that I'm using CMake 3.5, so there no longer is a <code>FindVTK.cmake</code> <a href="https://cmake.org/cmake/help/v3.5/module/FindVTK.html" rel="nofollow noreferrer">as it used to be</a>.</p>
  
  <p>What are the default search paths for <code>find_package()</code> and <code>include()</code>? Why is <code>vtkModuleAPI.cmake</code> not found?</p>