docs/CMakeLists.txt

+set(DOXYGEN_EXTRACT_ALL YES)
+set(DOXYGEN_BUILDIN_STL_SUPPORT YES)
+
+doxygen_add_docs(docs
+	WORKING_DIRECTORY "${PROJECT_SOURCE_DIR}/include"
+)

fggl/FgglConfig.h.in

+/*
+ * This file is part of FGGL.
+ *
+ * FGGL is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ *
+ * FGGL is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License along with FGGL.
+ * If not, see <https://www.gnu.org/licenses/>.
+ */
+
 // the configured options and settings for Tutorial
 #define FGGL_VERSION_MAJOR @FGGL_VERSION_MAJOR@
 #define FGGL_VERSION_MINOR @FGGL_VERSION_MINOR@
-

fggl/audio/fallback/CMakeLists.txt

+target_sources(fggl
+    PRIVATE
+        audio.cpp
+)