The Defold engine code structure

Browsing the engine code

To make it easier to find your way around the code, it's good to know about some of our naming conventions.

Naming conventions

• res_*.cpp - Resource types. These are responsible for loading/unloading a certain (compiled) asset type. E.g. res_sprite.cpp

• comp_*.cpp - Component types. Reponsible for creating a component world and instances. Matched with a resource type using the same filename extension. E.g. comp_sprite.cpp

• script_*.cpp - Script modules. These add new Lua modules to the engine. E.g. script_sprite.cpp

  • Exceptions to the rule: gameobject_script.cpp, gui_script.cpp and render_script.cpp

• *_ddf.proto - File formats. These are the file formats used for source and compiled content. sprite_ddf.proto

Libraries

This is the list of libraries in the defold/engine/<library> folder that are used to make up the engine. For the up-to-date list of libraries, see the ENGINE_LIBS in build.py

The order of these libraries is important as they determine the possible ways a library may use another library. E.g. render may use graphics, but the reverse order is not allowed.

• testmain - Helper library for unit tests and platform specific functionality.
• dlib - Our main util library with containers, sockets, I/O, compression etc
• texc - Our texture compiler. Creates a .jar+.dll for use with bob.jar
• modelc - Our model compiler. Creates a .jar+.dll for use with bob.jar
• ddf - Our runtime data format. It's a slimmed down version of Protobuf.
• platform - Handles some platform specific concepts, like a Window.
• graphics - Graphics layer with e.g. vertex buffers and shader programs. Backends for OpenGL, Vulkan etc.
• particle - A system for simulating particles. Used by comp_particle.cpp
• lua - The regular Lua 5.1 implementation.
• hid - Human Interface Device library that handles gamepads, mouse, keyboards and touch input.
• input - A higher level input system that maps HID events into input actions
• physics - A single frontend for our two physics engines Box 2D and Bullet 3D. Includes the source of Box2D (Bullet 3D is in defold/external, see notes below)
• resource - Resource system. Handles creation of resources, reference counting, and also mounting of resource archives.
• extension - API for registering native extensions (aka script extensions)
• script - A high level scripting interface that uses Lua as the backend.
• render - High level rendering concepts like materials, constants, cameras and render command buffer.
• rig - Our model+skeleton animation system.
• gameobject - Collections, game objects and component base functionality
• gui - Our gui system. Used by comp_gui.cpp
• sound - Our software sound mixing library
• liveupdate - High level functionality for downloadable content
• crash - Callstack callbacks and writing functionality
• gamesys - The main bulk of all resource types, component types and script modules.
• tools - Utilities like the gdc and the editor launcher
• record - Video (.avi) recording library. Current video format is the open vp8 codec in the ivf container.
• profiler - High level profiler api (using functionality from dlib's profile.h)
• engine - The defold engine libraries and executable
• sdk - Extra tests for our dmSDK headers.

Headers

When building the engine, some headers are copied from the local library folder, to the DYNAMO_HOME/include sub folders.

Similarly, we copy header files from any dmsdk sub folders from each library. These end up in the final SDK that our users use on a daily basis.

If you edit any of those header files, be aware of any breaking changes to the api!

Bob.jar

Our command line content build system is called Bob.jar. It is described here

External libraries

We keep certain versions of external code in defold/share/ext Since they change so rarely, we don't want them building in our main build step.

Examples are protobuf, tremolo and luajit

The output is stored in the repository, under defold/packages

External libraries pt 2

Since the projects under defold/share/ext are farily cumbersome to maintain and build, we have moved some to defold/external.

The benefit is that we can use the same build system for all platforms, which makes it easy to maintain such a library.

Currently includes Bullet 3D and glfw.

The output is stored in the repository, under defold/packages

See the readme for more detailed info.

Packages

Ìn defold/packages we store code/tools that are rarely updated. We unpack these packages with ./build.py install_ext and they're installed into the DYNAMO_HOME folder.