file(READ ${GLSL_FILE_ABSOLUTE} GLSL_FILE_CONTENTS)

set(INCLUDED_FILES)

function(resolve_includes CONTENTS OUTPUT)
  string(REGEX MATCHALL "#include \"([^\"]+)\"" INCLUDES "${CONTENTS}")

  foreach(INCLUDE ${INCLUDES})
    string(REGEX REPLACE "#include \"([^\"]+)\"" "\\1" INCLUDE_FILE ${INCLUDE})
    get_filename_component(INCLUDE_FILE_ABSOLUTE ${GLSL_SOURCE_DIRECTORY}/${INCLUDE_FILE} ABSOLUTE)
    list(FIND INCLUDED_FILES ${INCLUDE_FILE_ABSOLUTE} INCLUDE_FILE_INDEX)

    if(INCLUDE_FILE_INDEX EQUAL -1)
      list(APPEND INCLUDED_FILES ${INCLUDE_FILE_ABSOLUTE})
      file(READ ${INCLUDE_FILE_ABSOLUTE} INCLUDED_FILE_CONTENTS)
      resolve_includes("${INCLUDED_FILE_CONTENTS}" RESOLVED_CONTENTS)
      string(REPLACE "${INCLUDE}" "${RESOLVED_CONTENTS}" CONTENTS "${CONTENTS}")
    else()
      string(REPLACE "${INCLUDE}" "" CONTENTS "${CONTENTS}")
    endif()
  endforeach()
  
  set(${OUTPUT} "${CONTENTS}" PARENT_SCOPE)
  set(INCLUDED_FILES ${INCLUDED_FILES} PARENT_SCOPE)
endfunction()

list(APPEND INCLUDED_FILES ${GLSL_FILE_ABSOLUTE})
resolve_includes("${GLSL_FILE_CONTENTS}" RESOLVED_GLSL_FILE_CONTENTS)

# Convert to C string
string(REPLACE "\"" "\\\"" RESOLVED_GLSL_FILE_CONTENTS "${RESOLVED_GLSL_FILE_CONTENTS}")
string(REPLACE "\n" "\\n\"\n\"" RESOLVED_GLSL_FILE_CONTENTS "${RESOLVED_GLSL_FILE_CONTENTS}")
set(RESOLVED_GLSL_FILE_CONTENTS "\"${RESOLVED_GLSL_FILE_CONTENTS}\\n\"")

# Write to header file
file(WRITE ${GLSL_FILE_HEADER} "const char* ${GLSL_FILE_NAME_WE}ShaderSource = ${RESOLVED_GLSL_FILE_CONTENTS};")