See the list of requirements and install the required build tools and third-party libraries. OVITO should be compiled with Apple's clang C++ compiler shipping with Xcode. It's easiest to use MacPorts for installing many of the required dependencies. After setting up MacPorts, run

sudo port install netcdf pzlib libssh boost cmake docbook-xml doxygen libxslt yasm

from the terminal to install the dependencies of OVITO.

Next, download and install Qt 5.12.x for Mac.

Next, download the source code and build the shared version of the ffmpeg video encoding library (optional):

curl -O https://ffmpeg.org/releases/ffmpeg-4.2.1.tar.gz
tar xzfv ffmpeg-4.2.1.tar.gz
cd ffmpeg-4.2.1
./configure \
	--disable-network \
	--disable-programs \
	--disable-debug \
	--disable-doc \
  --disable-static \
  --enable-shared \
	--prefix=$HOME/ffmpeg
make install

To download OVITO's source code into a new directory named ovito, run:

git clone https://gitlab.com/stuko/ovito.git

Within the source directory, create a build sub-directory and let CMake generate the Makefile:

cd ovito
mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release \
      -DCMAKE_INSTALL_PREFIX=../install \
      -DCMAKE_PREFIX_PATH=`echo $HOME/Qt/5.*.*/clang_64/` \
      -DFFMPEG_INCLUDE_DIR=$HOME/ffmpeg/include \
      -DFFMPEG_LIBRARY_DIR=$HOME/ffmpeg/lib \
      ..

Adjust the paths in the command above as needed. If this step fails, or if you want to disable individual components of OVITO, you can now run "ccmake ." to open the CMake configuration program and make changes to the build settings. Once you are done, build OVITO by running

make -j4

If this step succeeds, you can run make install to generate an app bundle in the ovito/install/ directory.