title: Copying assets directory from source to build directory in CMake
body: <p>I am trying to write a game for practice in C++. I am using CMake for this, and my project gets built in a separate build directory automatically by my IDE. However, my <code>assets</code> folder is <em>not</em> being copied over to the new directory.</p>
  
  <p>Currently, I am attempting to resolve this with the following:</p>
  
  <pre><code>add_custom_command(TARGET ${PROJECT_NAME}
      POST_BUILD
      COMMAND cp -r ${PROJECT_SOURCE_DIR}/assets ${CMAKE_BINARY_DIR}
      )
  </code></pre>
  
  <p>However, this seems to have absolutely no effect on the outcome and the assets directory is still <em>not</em> present in my build directory.</p>
  
  <p>How can I actually make it copy this asset directory to my build location? Is there a smarter way to point my program to my assets location (perhaps one that will also work with assets in /usr/share?)</p>