* Things To Do

** DONE Game loop
   Provide a game loop structure that responds to input events,
   updates the game state, renders the scene. Use a fixed update
   timestep and cap the maximum FPS.

** DONE Game scenes
   Games can be broken up into many chunks, called scenes. Examples
   would be a main menu, a world map, a battle screen, etc.

   - [X] Create a <scene> type that encapsulates input/render/update
     callbacks
   - [X] Macro for declaratively defining a scene
   - [X] Scene switching

** TODO Input
   Provide hooks to respond to keyboard, mouse, and joystick events.
   Wrap SDL keycode, mouse button, etc. constants in our own
   enumeration.

   - [X] Keyboard
   - [X] Mouse
   - [X] Window (active, resize, quit)
   - [ ] Joystick

** DONE Sprites
   Encapsulates an image and all of its transformations: position,
   rotation, scale, color, etc.

   - [X] Use FreeImage
   - [X] Add support for texture regions
   - [X] Add support for animations
   - [X] Use a sprite batch when drawing if one is currently bound

** TODO Sprite batches
   Efficiently render a large number of sprites. Only change OpenGL
   context when necessary. For example, don't change texture when
   rendering several sprites in a row that use the same one.

   - [X] Add basic batching for non-scaled, non-rotated sprites
   - [X] Add transformation logic for scaling and rotating
   - [X] Add support for colors
   - [ ] Add support for different blending modes

** DONE Tilesets
   Break an image up into many small pieces. Useful for creating maps.

   - [X] Algorithm to split texture into tiles
   - [X] <tileset> type

** DONE Animations
   Create a data type to represent an animated sequence of textures
   and/or texture regions.

** TODO Tile maps
   - [ ] Create a generic tilemap module
   - [ ] Create a loader for Tiled .tmx map files.

** TODO Scene graph
   A tree structure that is traversed when rendering a game scene.
   The graph is composed of groups and nodes. Transformations are
   accumulated as the tree is walked.

** DONE Scripting
   Provide a way for users to easily script 2D games using coroutines
   and a scheduler.

   - [X] Coroutines
   - [X] Agenda

** TODO Vectors and matrices
   Vectors and matrices are needed constantly for games. Provide an
   easy-to-use module that provides procedures for common
   vector/matrix math operations

   - [X] Vectors
   - [ ] Matrices

** DONE Fonts
   - [X] Write wrappers for needed FTGL functions
   - [X] Write font rendering procedures

** TODO Sound
   Provide helpful wrappers around SDL sound procedures?

** TODO A* pathfinding
   A* is a commonly used pathfinding algorithm for games. Pathfinding
   is such a common task that it would be nice to provide users with
   a generic implementation.

** TODO Bounding box collision detection
   Most games need simple bounding box collision detection. Provide an
   efficient implementation that uses quad trees.

   - [X] Rect module
   - [ ] Quadtree module

** TODO Particle systems
   Provide a highly configurible particle simulation system.

** TODO Asset Management
   Provide a generic system for loading assets (images, sounds, fonts,
   etc.) and storing them in a cache. Explore using weak keys so that
   assets are removed from the cache when they are no longer
   referenced.

** TODO Actions
   Provide a library of coroutines that perform commonly used
   time-based actions such as linear interpolation. It would be nice
   to have a way to make these easily composable as well.

   - [X] Make actions composable
   - [X] Linear interpolation (lerp)
   - [ ] Move to/move by

** TODO Keymaps
   Provide an Emacs-like way of defining key combinations so that
   multi-button input is easy for users.

   The more I think about what I want, the more I realize that I am
   describing a system that uses functional reactive programming.

   - [ ] Abstract away input methods

     Controls can be bound to keys, mouse, whatever

   - [ ] Basic sequences

     Press A then B

   - [ ] Simultaneous key presses

     Press A and B at the same time

   - [ ] Composing sequences

     Press A then B + C

   - [ ] Timeouts

     Press A then B then C within 15 frames time

   - [ ] Sequences with actions along the way

     Press A to kick, then forward + B to uppercut, within 30 frames
     time.


** TODO GUI widgets
   Provide a set of common graphical widgets such as buttons, scroll
   bars, and sliders.

** TODO REPL
   Provide a REPL that plays nice with the game loop. Easier said than
   done.

   - [X] Modify Guile's REPL to work with the game loop
     - Short-term solution that *mostly* works
   - [ ] Write a new REPL that runs in the current thread
     - Use coroutines
     - Read user input from a separate thread so as to not block the
       main thread

** TODO 0.1 Release
   An official 0.1 alpha release with basic, minimal functionality
   will provide a good place for people other than me to try out
   guile-2d and perhaps even start to hack on it.

   - [X] Font rendering with FTGL
   - [ ] Resolve issues with FIGL
   - [ ] Texinfo documentation
   - [X] Autotools build files
   - [ ] Fix animation bug