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Compiling LÖVR

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Compiling the LÖVR code yourself lets you create a custom LÖVR build so you can add your own features or run it on other operating systems. Below is a guide for setting up all the dependencies and compiling the code on various types of systems.

Contents

System Requirements

LÖVR is currently known to work with (and optimized for)

Other systems and hardware may work, but are not frequently tested.

Dependencies

LÖVR uses the following libraries. They are included as submodules in the deps directory of the repository, so make sure you clone with the --recursive flag or run git submodule update --init --recursive in an existing repository.

LÖVR requires a C compiler that supports C11. GCC 4.9, clang 3.1, and Windows SDK 2104 support C11.

Windows

From the lovr folder, run these commands to create a build folder and compile the project using CMake:

$ mkdir build
$ cd build
$ cmake ..
$ cmake --build .

The executable will then exist at /path/to/lovr/build/Debug/lovr.exe. A LÖVR project (a folder containing a main.lua script) can then be dropped onto lovr.exe to run it, or it can be run via the command line as lovr.exe path/to/project.

macOS

Build using CMake, as above:

$ mkdir build
$ cd build
$ cmake ..
$ cmake --build .

The lovr executable should exist in lovr/build/bin now. It's recommended to set up an alias or symlink so that this executable can be found in your PATH environment variable. Once that's done, you can run a project like this:

$ lovr /path/to/myGame

Linux

Install a C compiler and CMake, then run:

$ mkdir build
$ cd build
$ cmake ..
$ cmake --build .

LÖVR can use either SteamVR or monado as the VR runtime on Linux.

To use LÖVR with SteamVR on Linux, LÖVR needs to run within the Steam Runtime. To do this, first install Steam. Next, install the Steam udev rules. Then, run LÖVR within the Steam runtime:

$ ~/.local/share/Steam/ubuntu12_32/steam-runtime/run.sh lovr

If you receive errors related to libstdc++, set the LD_PRELOAD environment variable when running the command:

$ LD_PRELOAD='/usr/$LIB/libstdc++.so.6 /usr/$LIB/libgcc_s.so.1' ~/.steam/steam/ubuntu12_32/steam-runtime/run.sh lovr

Android

Here be dragons.

You will need to compile on a macOS or Linux system. Compiling LÖVR APKs on Windows does not currently work (unless all steps are performed in Windows Subsystem for Linux).

First, make sure the Java JDK is installed (version 17 is known to work).

Then, the Android SDK and NDK need to be installed. SDK version 29 should be installed.

The Android command line tools can be found on the Android website or installed using a package manager. The command line tools contain a tool named sdkmanager that can be used to install various versions of Android, the Android build tools, and the NDK:

$ cmdline-tools/bin/sdkmanager --sdk_root=/path/to/android/sdk "build-tools;34.0.0" "cmake;3.22.1" "ndk;21.4.7075529" "platform-tools" "platforms;android-29"

The SDK will be installed to the chosen sdk_root path. To reduce the SDK size, the emulator package can be safely uninstalled:

$ cmdline-tools/bin/sdkmanager --sdk_root=/path/to/android/sdk --uninstall emulator

Android Studio isn't required, but can be used to install the SDK, NDK, and Java as well.

Note where the SDK is installed. Some paths in the SDK will need to be specified.

Finally, compiling a LÖVR APK requires a copy of the glslangValidator tool installed on the system. Most package managers will offer this as part of a "glslang" or "glslang-tools" package.

CMake or tup can be used to build an APK that can be installed on an Android device.

tup

Add a tup.config file in the repository root. The config values to fill in are:

Once all of this is set up, run tup init if tup hasn't been initialized yet. Then run tup to build the APK, output in the bin folder.

CMake

The following CMake variables need to be set, either using the CMake GUI or by using -D flags on the command line:

The usual CMake incantation with all of the above variables set up should produce lovr.apk:

$ mkdir build
$ cd build
$ cmake \
    -D CMAKE_TOOLCHAIN_FILE=/path/to/ndk/build/cmake/android.toolchain.cmake \
    -D ANDROID_SDK=/path/to/android \
    -D ANDROID_ABI=arm64-v8a \
    -D ANDROID_NATIVE_API_LEVEL=29 \
    -D ANDROID_BUILD_TOOLS_VERSION=34.0.0 \
    -D ANDROID_KEYSTORE=/path/to/test.keystore \
    -D ANDROID_KEYSTORE_PASS=pass:hunter2 \
    ..
$ cmake --build .

Installing the APK

To install the APK, an Android device needs to be connected. Run

$ adb devices

to ensure that a device is connected, then run

$ adb install lovr.apk

To install the apk. The -r flag can be used to overwrite an existing apk.

Adding Project Code

To build an apk that runs a LÖVR project, pass the folder path as the ANDROID_ASSETS option to either CMake or tup. This will run the LÖVR project when the apk starts, similar to how things work when fusing a zip to an exe on desktop systems.

Note: By default the Android packager ignores directories that begin with underscores.

Using a Custom Android Manifest

Although LÖVR provides a default AndroidManifest.xml, you can also use your own by passing its path as the ANDROID_MANIFEST option to either CMake or tup. This can be used to request extra permissions, change the package ID or app name, etc.

Any file named AndroidManifest*.xml will be ignored in LÖVR's git repository.

Changing the Package ID

LÖVR extracts the package name from the AndroidManifest.xml file (org.lovr.app by default). To use a different package id, edit etc/AndroidManifest.xml, or set the ANDROID_MANIFEST CMake variable to set a custom manifest with a different package id.

Creating a Keystore

A keystore file needs to be generated, which is used to sign the APK after it's built.

To generate a keystore, use Java's keytool tool:

$ keytool -genkey -keystore <name>.keystore -alias <name> -keyalg RSA -keysize 2048 -validity 10000

When specifying the password for the keystore, it can be done in multiple ways:

Troubleshooting