Use user provided lib/irrlichtmt if available (#11276)

Use user provided lib/irrlichtmt if available Make it possible for a user to provide the IrrlichtMt dependency as subdirectory at `lib/irrlichtmt`. The subdirectory is added with the `EXCLUDE_FROM_ALL` flag to prevent `libirrlichtmt.a` or other header files to be installed. This enables the user to do the following to satisfy the IrrlichtMt dependency: git clone --depth 1 https://github.com/minetest/irrlicht.git lib/irrlichtmt cmake . -DRUN_IN_PLACE=TRUE
minetest · Jun 29, 2021 · fa4dee0 · fa4dee0
1 parent 63fc728
commit fa4dee0
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Showing 3 changed files with 36 additions and 5 deletions.
diff --git a/.gitignore b/.gitignore
@@ -106,3 +106,6 @@ CMakeDoxy*
 compile_commands.json
 *.apk
 *.zip
+
+# Optional user provided library folder
+lib/irrlichtmt
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -58,11 +58,27 @@ set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake/Modules/")
 
 
 # This is done here so that relative search paths are more reasonable
-find_package(Irrlicht)
-if(BUILD_CLIENT AND NOT IRRLICHT_FOUND)
-	message(FATAL_ERROR "IrrlichtMt is required to build the client, but it was not found.")
-elseif(NOT IRRLICHT_INCLUDE_DIR)
-	message(FATAL_ERROR "Irrlicht or IrrlichtMt headers are required to build the server, but none found.")
+if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/lib/irrlichtmt")
+	message(STATUS "Using user-provided IrrlichtMt at subdirectory 'lib/irrlichtmt'")
+	# tell IrrlichtMt to create a static library
+	set(BUILD_SHARED_LIBS OFF CACHE BOOL "Build shared library" FORCE)
+	add_subdirectory(lib/irrlichtmt EXCLUDE_FROM_ALL)
+	unset(BUILD_SHARED_LIBS CACHE)
+
+	if(NOT TARGET IrrlichtMt)
+		message(FATAL_ERROR "IrrlichtMt project is missing a CMake target?!")
+	endif()
+
+	# set include dir the way it would normally be
+	set(IRRLICHT_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/lib/irrlichtmt/include")
+	set(IRRLICHT_LIBRARY IrrlichtMt)
+else()
+	find_package(Irrlicht)
+	if(BUILD_CLIENT AND NOT IRRLICHT_FOUND)
+		message(FATAL_ERROR "IrrlichtMt is required to build the client, but it was not found.")
+	elseif(NOT IRRLICHT_INCLUDE_DIR)
+		message(FATAL_ERROR "Irrlicht or IrrlichtMt headers are required to build the server, but none found.")
+	endif()
 endif()
 
 include(CheckSymbolExists)

diff --git a/README.md b/README.md
@@ -177,6 +177,10 @@ Download minetest_game (otherwise only the "Development Test" game is available)
 
     git clone --depth 1 https://github.com/minetest/minetest_game.git games/minetest_game
 
+Download IrrlichtMt to `lib/irrlichtmt`, it will be used to satisfy the IrrlichtMt dependency that way:
+
+    git clone --depth 1 https://github.com/minetest/irrlicht.git lib/irrlichtmt
+
 Download source, without using Git:
 
     wget https://github.com/minetest/minetest/archive/master.tar.gz
@@ -191,6 +195,14 @@ Download minetest_game, without using Git:
     mv minetest_game-master minetest_game
     cd ..
 
+Download IrrlichtMt, without using Git:
+
+    cd lib/
+    wget https://github.com/minetest/irrlicht/archive/master.tar.gz
+    tar xf master.tar.gz
+    mv irrlicht-master irrlichtmt
+    cd ..
+
 #### Build
 
 Build a version that runs directly from the source directory: