Just last little bits of polish

cmake/copy_resources.cmake

@@ -2,6 +2,20 @@ if(NOT DEFINED SRC_DIR OR NOT DEFINED DST_DIR)
     message(FATAL_ERROR "SRC_DIR and DST_DIR must be defined")
 endif()
 
+set(CHARACTERS_DIR "${SRC_DIR}/characters")
+set(CHARACTERS_ZIP_SCRIPT "${CHARACTERS_DIR}/zip")
+
+if(EXISTS "${CHARACTERS_ZIP_SCRIPT}")
+    execute_process(
+            COMMAND "${CHARACTERS_ZIP_SCRIPT}"
+            WORKING_DIRECTORY "${CHARACTERS_DIR}"
+            RESULT_VARIABLE ZIP_SCRIPT_RESULT
+    )
+    if(NOT ZIP_SCRIPT_RESULT EQUAL 0)
+        message(FATAL_ERROR "Failed running ${CHARACTERS_ZIP_SCRIPT} (exit code ${ZIP_SCRIPT_RESULT})")
+    endif()
+endif()
+
 file(REMOVE_RECURSE "${DST_DIR}")
 file(MAKE_DIRECTORY "${DST_DIR}")
 
@@ -11,7 +25,7 @@ file(COPY "${SRC_DIR}/" DESTINATION "${DST_DIR}"
 
 # Copy only .zip archives from resources/characters.
 file(MAKE_DIRECTORY "${DST_DIR}/characters")
-file(GLOB CHARACTER_ZIPS "${SRC_DIR}/characters/*.zip")
+file(GLOB CHARACTER_ZIPS "${CHARACTERS_DIR}/*.zip")
 if(CHARACTER_ZIPS)
     file(COPY ${CHARACTER_ZIPS} DESTINATION "${DST_DIR}/characters")
 endif()