Add the doxygen cmake file to the CMake Project

Make the docs its own target instead of a project. Dont add the
new docs target to ALL. Add an option to disable generating the
docs.
Update doxygen_awesome to v2.4.2.
Update README to reflect new changes.

CMakeLists.txt

@@ -4,6 +4,7 @@ project(0ad VERSION 0.29.0)
 
 # Available Options
 option(android "Use non-working Android cross-compiling mode")
+option(build-docs "Enable building the doxygen documentation(requires Network access)")
 option(coverage "Enable code coverage data collection (GCC only)")
 option(gles "Use non-working OpenGL ES 2.0 mode")
 option(jenkins-tests "Configure CxxTest to use the XmlPrinter runner which produces Jenkins-compatible output")
@@ -144,3 +145,8 @@ include(0ad-BuildFlags)
 if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
 	include(SetupWindowsLibs)
 endif()
+
+# Add doxygen target
+if(build-docs)
+	add_subdirectory(${CMAKE_SOURCE_DIR}/docs/doxygen)
+endif()

docs/README.md

@@ -6,7 +6,11 @@
 
 ## Building the Doxygen documentation
 
-To generate the Doxygen documentation: run "cmake -S . -B output && cmake --build output".
+To generate the Doxygen documentation:
+
+```console
+cmake -S 0ad/rootdir -B output && cmake --build output --target docs
+```
 
 If you build the documentation with cmake, the output is located in the folder html inside your
 specified build directory.

docs/doxygen/CMakeLists.txt

@@ -1,6 +1,4 @@
-cmake_minimum_required(VERSION 3.18.4...3.28.0)
+cmake_minimum_required(VERSION 3.25.1...4.0.0)
-
-project(Pyrogenesis DESCRIPTION "Pyrogenesis, a RTS Engine" LANGUAGES NONE)
 
 # Check if Doxygen and graphviz are installed.
 find_package(Doxygen 1.9.1 REQUIRED dot)
@@ -9,9 +7,10 @@ if(DOXYGEN_FOUND)
 
 	include(FetchContent)
 
+	message(STATUS "Fetching doxygen_awesome_css")
 	FetchContent_Declare(doxygen_awesome_css
 		GIT_REPOSITORY	https://github.com/jothepro/doxygen-awesome-css
-        GIT_TAG        v2.3.3
+		GIT_TAG			v2.4.2
 		SOURCE_DIR		${CMAKE_CURRENT_BINARY_DIR}/styling
 	)
 	FetchContent_MakeAvailable(doxygen_awesome_css)
@@ -27,6 +26,8 @@ if(DOXYGEN_FOUND)
 	endif()
 
 	# Doxygen Configuration.
+	set(DOXYGEN_PROJECT_NAME "Pyrogenesis")
+	set(DOXYGEN_PROJECT_BRIEF "Pyrogenesis, a RTS Engine")
 	if(CURRENT_BRANCH)
 		set(DOXYGEN_PROJECT_NUMBER ${CURRENT_BRANCH})
 	else()
@@ -35,9 +36,9 @@ if(DOXYGEN_FOUND)
 	set(DOXYGEN_PROJECT_LOGO ${CMAKE_CURRENT_SOURCE_DIR}/pyrogenesis.png)
 	set(DOXYGEN_TAB_SIZE 4)
 	set(DOXYGEN_EXCLUDE_PATTERNS */.svn* */tests/test_*)
-    set(DOXYGEN_INCLUDE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/../../source)
+	set(DOXYGEN_INCLUDE_PATH ${CMAKE_SOURCE_DIR}/source)
-    set(DOXYGEN_EXAMPLE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/../../source)
+	set(DOXYGEN_EXAMPLE_PATH ${CMAKE_SOURCE_DIR}/source)
-    set(DOXYGEN_EXCLUDE ${CMAKE_CURRENT_SOURCE_DIR}/../../source/tools ${CMAKE_CURRENT_SOURCE_DIR}/../../source/third_party)
+	set(DOXYGEN_EXCLUDE ${CMAKE_SOURCE_DIR}/source/tools ${CMAKE_SOURCE_DIR}/source/third_party)
 	set(DOXYGEN_GENERATE_TREEVIEW YES)
 	set(DOXYGEN_HTML_EXTRA_STYLESHEET ${doxygen_awesome_css_SOURCE_DIR}/doxygen-awesome.css ${CMAKE_CURRENT_SOURCE_DIR}/style.css)
 	set(DOXYGEN_JAVADOC_AUTOBRIEF YES)
@@ -54,11 +55,12 @@ if(DOXYGEN_FOUND)
 	set(DOXYGEN_EXPAND_AS_DEFINED DEFAULT_COMPONENT_ALLOCATOR DEFAULT_SCRIPT_WRAPPER DEFAULT_INTERFACE_WRAPPER DEFAULT_MESSAGE_IMPL MESSAGE INTERFACE COMPONENT GUISTDTYPE)
 	set(DOXYGEN_WARN_LOGFILE doxygen.log)
 
-    doxygen_add_docs(${CMAKE_PROJECT_NAME}
+	doxygen_add_docs(docs
-             ${CMAKE_CURRENT_SOURCE_DIR}/../../source
+		${CMAKE_SOURCE_DIR}/source
 		${CMAKE_CURRENT_SOURCE_DIR}/mainpage.dox
-             ${CMAKE_CURRENT_SOURCE_DIR}/../../LICENSE.md
+		${CMAKE_SOURCE_DIR}/LICENSE.md
-            ALL)
+		COMMENT "Creating Doxygen for the engine."
+	)
 else()
 	message(SEND_ERROR "Make sure Doxygen is installed and usable")
 endif()