libopenmpt-godot

This is a GDNative library that allows you to use libopenmpt within the Godot Engine.

Related Reading

See this article for a detailed description of why this was made.

Compilation Instructions

You will have to first download the [Godot C++ Bindings][godot-cpp] for your target Godot version and then place the godot-cpp folder in the project root folder.

You will need to have libopenmpt (>= 0.6.5) installed in your system to compile this library.

For Windows

Download the official compiled binaries from lib.openmpt.org and extract them into deps/libopenmpt.

For Linux

First you need to compile libopenmpt for your system, if you don't have it installed already and don't have the appropriate version.

First, obtain the source code from lib.openmpt.org and extract it into deps/libopenmpt, open a terminal in the same directory and run the following commands:

CPPFLAGS=-fPIC ./configure --prefix=$(realpath ./install-files) --disable-openmpt123
make
make install

This will put the required libraries into deps/libopenmpt/install-files.

Building

In the root directory, open a terminal and run:

scons platform=<platform name> target=<debug/release>

to build binaries for your system.

Advanced Configuration

You can edit the SConstruct file in case you are not able to perform the build properly or want to change libopenmpt's library or header file directories. These are the lines that you should look for and change:

# libopenmpt-specific variables
# The windows version is based on the official libopenmpt distribution
# The linux version is based on direct compilation of the library.
if platform == "windows":
	libopenmpt_path = "deps/libopenmpt"
	libopenmpt_headers_path = libopenmpt_path + "/inc"
	libopenmpt_lib_path = libopenmpt_path + "/lib"
else:
	libopenmpt_path = "deps/libopenmpt/install-files"
	libopenmpt_headers_path = libopenmpt_path + "/include"
	libopenmpt_lib_path = libopenmpt_path + "/lib"

Post-Installation

You will want to set the platform-specific paths for the compiled library in project/gdnative/libopenmpt-godot.gdnlib. Curently only the 64-bit Linux path is set.

Usage

See the project directory for an example Godot Project. The GDNative class implements the same interface as openmpt::module. The NativeScript must be first be initialized either by assigning the script to a node or possibly instantiated and to a script variable using new().

Then the module_file_path property of the object must be set to a valid module file.

var module = $path/to/module/node
module.module_file_path = "song.it"

An AudioStreamPlayer node must be created with the stream field/variable set to an AudioStreamGenerator. Then the buffer_length field of the AudioStreamGenerator must be set to a small value (say 0.1) so that the song and our current song position information do not go out of sync.

Then the AudioStreamPlayer must be assigned to the script object like this:

module.set_audio_generator_playback(audio_stream_player)

This will now allow the audio_stream_player to play the audio being rendered by the library.

To actually start the rendering, call the start() function:

module.start()

Bugs and Issues

Currently set_audio_generator_playback only supports an AudioStreamPlayer as an argument. This could be easily resolved by declaring more functions to accept the other AudioStreamPlayer types. The function body should remain the same, except for the type.

If you find any more bugs and issues with the library, feel free to report them in the Github Issues section.

Licensing

This project is licensed under the MIT/X11 license. See LICENSE for details.