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irr/README.md

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+IrrlichtMt version 1.9
+======================
+
+IrrlichtMt is the 3D engine of [Minetest](https://github.com/minetest).
+It is based on the [Irrlicht Engine](https://irrlicht.sourceforge.io/) but is now developed independently.
+It is intentionally not compatible to upstream and is planned to be eventually absorbed into Minetest.
+
+Build
+-----
+
+The build system is CMake.
+
+The following libraries are required to be installed:
+* zlib, libPNG, libJPEG
+* OpenGL
+  * or on mobile: OpenGL ES (can be optionally enabled on desktop too)
+* on Unix: X11
+* SDL2 (see below)
+
+Aside from standard search options (`ZLIB_INCLUDE_DIR`, `ZLIB_LIBRARY`, ...) the following options are available:
+* `BUILD_SHARED_LIBS` (default: `ON`) - Build IrrlichtMt as a shared library
+* `BUILD_EXAMPLES` (default: `OFF`) - Build example applications
+* `ENABLE_OPENGL` - Enable OpenGL driver
+* `ENABLE_OPENGL3` (default: `OFF`) - Enable OpenGL 3+ driver
+* `ENABLE_GLES1` - Enable OpenGL ES driver, legacy
+* `ENABLE_GLES2` - Enable OpenGL ES 2+ driver
+* `USE_SDL2` (default: platform-dependent, usually `ON`) - Use SDL2 instead of older native device code
+
+e.g. on a Linux system you might want to build for local use like this:
+
+	git clone https://github.com/minetest/irrlicht
+	cd irrlicht
+	cmake . -DBUILD_SHARED_LIBS=OFF
+	make -j$(nproc)
+
+This will put an IrrlichtMtTargets.cmake file into the cmake directory in the current build directory, and it can then be imported from another project by pointing `find_package()` to the build directory, or by setting the `CMAKE_PREFIX_PATH` variable to that same path.
+
+on Windows system:
+
+It is highly recommended to use vcpkg as package manager.
+
+After you successfully built vcpkg you can easily install the required libraries:
+
+	vcpkg install zlib libjpeg-turbo libpng sdl2 --triplet x64-windows
+	
+Run the following script in PowerShell:
+
+	git clone https://github.com/minetest/irrlicht
+	cd irrlicht
+	cmake -B build -G "Visual Studio 17 2022" -A "Win64" -DCMAKE_TOOLCHAIN_FILE=[vcpkg-root]/scripts/buildsystems/vcpkg.cmake -DBUILD_SHARED_LIBS=OFF
+	cmake --build build --config Release
+	
+Platforms
+---------
+
+We aim to support these platforms:
+* Windows via MinGW
+* Linux (GL or GLES)
+* macOS
+* Android
+
+This doesn't mean other platforms don't work or won't be supported, if you find something that doesn't work contributions are welcome.
+
+License
+-------
+
+The license of the Irrlicht Engine is based on the zlib/libpng license and applies to this fork, too.
+
+	The Irrlicht Engine License
+	===========================
+
+	Copyright (C) 2002-2012 Nikolaus Gebhardt
+
+	This software is provided 'as-is', without any express or implied
+	warranty.  In no event will the authors be held liable for any damages
+	arising from the use of this software.
+
+	Permission is granted to anyone to use this software for any purpose,
+	including commercial applications, and to alter it and redistribute it
+	freely, subject to the following restrictions:
+
+	1. The origin of this software must not be misrepresented; you must not
+	 claim that you wrote the original software. If you use this software
+	 in a product, an acknowledgement in the product documentation would be
+	 appreciated but is not required.
+	2. Altered source versions must be clearly marked as such, and must not be
+	 misrepresented as being the original software.
+	3. This notice may not be removed or altered from any source distribution.