Last Ludum Dare I implemented a circular world for my game. I wanted to do that for some time, but before this LD I had no idea how to implement such a thing. Now I see that is pretty easy to do so. In this post I will explain how to create a circular world like the one I used in Democracy.

The beauty of a circular world is that we can work only with the radius of the planet, ignoring its position at the screen. So, first thing to do is defining our planet to a radius “r” (lets say 150px) and to screen position (0, 0). To center the planet in the window, you move the camera to (-w/2, -h/2) where w is the window width and h is the window height. You should see something like this:


Now that we have an empty world, lets add some objects on it. All objects must have a position in this world, but this position isn’t the same of in screen, it is simpler. Suppose that at the point (0, r), what could be the north of our planet, is the angle 0°, then the east (r, 0) is 90° and so on, until the north point again. See the image below for reference:


Now our object can be at positions like 47° or 270°, but we still must draw it into the screen. That’s pretty simple. Let’s say we have a sprite with (s_w, s_h), width and height, respectively. Then we set its screen position to (0, 0) and its anchor to (0, r+s_h). With this we have an sprite at the north point 0°, to relocate it to 306° we simply set its rotation as “sprite.rotation = 306” and done!


White box is at north (0°) and the red box is at 306°.

Additionally you can also set the height of the object in that world (the distance of that object to the ground). To put a cloud at 30px high, you simply add the height to the sprites anchor, such that anchor is (0, r + s_w + height):


Sometimes you may find useful to convert the world position, now (position, height), to the screen position. For example, to add some particles. So, to find the screen coordinates (x, y) of an object at (position, height) you do:

angle = radians(position);
x = sin(angle) * r + height;
y = -cos(angle) * r + height;

Contrarily, when you want to convert the screen position to world coordinates, for example to find where the mouse is pointing. You can do:

position = degrees(atan2(mouse.y - camera.y, mouse.x - camera.x));
height = euclidDistance(mouse.x, mouse.y, camera.x, camera.y) - r;

Simple right?

Let me know if you found this article useful, or if you have an alternative way to do that, or yet, if you created some circular world based on this. Cheers!

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Ludum Dare is great! Not just because it motivates me to create (and finish) a new game, but also because I use it to update Creatine. So, as usual, after the compo I’m releasing another version creatine, now the release 1.0.0!

This version is big. It has a lot of new stuff and a lot of changes for the old features. But before talking about the modifications and additions to the library, let me talk about how I was felling about creatine 0.2…

To be honest, I wasn’t happy about the previous version, I added several classes to handle storage, sound, layout, scenes, among other things. But they weren’t working together, there were some annoying bugs (in special with transitions) and I was spending a good time rewriting the same base structure for new games, over and over.  So I decided to rethink some things: how can I make my development easier and faster? My conclusions and desires after that:

  • I want to use a visual editor to build my scenes, something like Overlap2D or one tool of my own.
  • I need more flexibility for fast prototypes (sometimes I just want to test some idea).
  • Modularity is cool, but is not a great deal. A class that controls all modules would be more useful and would save some time by eliminating the base common structure that I was rewriting every project.
  • I need more fluffy things, more juice, which means that have to be easy to add particles and visual or sound effects to the game.
  • I want to have a physic system and other predefined behaviors easy to use in my games (such as a platform system, or 2d top-down movement and collision system).
  • Other details that I don’t remember right now (it is Sunday 11PM, give me a break!).

With these things in mind, I started to update creatine.


The main addition to creatine is the Game object. The game is now the core of my library, because it is the responsible to create and initialize all game systems. For example: it is the game that creates the canvas element; the game also stores all creatine helpers (now called managers), such as the director (SceneManager), the device,  display and many others.

The game class is based on Phaser core, so if you know Phaser you may find this familiar. A game has 5 states: ”boot”, “preload”, “create”, “update” and “draw”. In the boot state you can initialize 3th-party libraries and some configuration of the engine. In preload, you will set which files should be loaded by the engine and may be show a preload scene. In the create state you will create and initialize all game objects, including scenes and object pools. The update and draw states are the main loop, and are executed every tick. You can use these state by passing functions to the game:

var game = new tine.Game(null, {
  boot    : function() {},
  preload : function() {},
  create  : function() {},
  update  : function() {},
  draw    : function() {}

The first argument of the Game class is the configuration object. This could be only an url to a JSON file containing the configuration. Notice that, with this, I will try to keep all engine data-driven, so you will be able to configure everything using this parameter. Right now, it has the following default values:

  project          : 'creatine_game',
  width            : 800,
  height           : 600,
  container        : null,
  framerate        : 60,
  background_color : '#000',
  resources        : {
    base_path : './',
    manifest  : []

To set configuration you can do:

var game = new tine.Game({framerate:30, width:300, height:500});

or yet:

var game = new tine.Game('myconfig.json')

where ‘myconfig.json’ is the json file containing the configuration values.

Resources and Factories

Creatine now have an interface to PreloadJS (the ResourceManager) and a factory manager. The resource manager helps you to load general assets in a more pleasant way and also helps you to load specific assets (such as spritesheets and audiosprites) in an easier way. For example, now you can set which files you want to preload in the preload state:

var game = new tine.Game(null, {
  preload: function() {
    game.load.image('id', 'src.png');
    game.load.spritesheet('id2', 'src.png', data);
    game.load.json('id3', 'data.json');

Or you could define these assets in the manifest (pretty much like how you do with PreloadJS):

var game = new tine.Game({resources: {
  manifest: [
    {id:'id', src:'src.png'},
    {id:'id2', src:'src.png', data:{stuff here}, type:'spritesheet'},

With your stuff loaded, you can create objects easier:

var game = new tine.Game(null, {
  preload: function() { ... },

  create: function() {
    var bitmap = game.create.bitmap('id', {x:100, y:400, regX:'center', regY:'bottom'});
    var sprite = game.create.sprite('id2', 'animation');
    var map = game.create.tilemap('id3');


Scenes and Transitions

Scenes now have some default method that you should override to use, such as “enter”, “pause”, “resume”… To create a scene, you must define a new class inheriting the scene class, an easy way to do that is by using the new shortcut:

var MyScene = tine._scene({
  initialize: function() { ... },
  enter: function() { ... },
  update: function() { ... },

You can also create your scenes before starting the application and register them to the director, using an unique identifier:

var game = new tine.Game(null, {
  create: function() {
    // Create scenes here

    // Add your scenes to the director
    game.director.add('menu', new MyMenuScene());
    game.director.add('level', new MyLevelScene());

    // Run a scene

Transitions are now working as they should be! You can use any transition in any function (replace, push or pop), repeatedly, or without having to wait the current transition.

Input handlers

We have input now! Keyboard, gamepads, mouse and touch. They don’t work together yet, but they are pretty cool already. Instead of putting code here, I suggest that you take a look into the creatine example folder and into the API documentation.

In the next releases I want to create a common Input or Control object that group all type of inputs together. So instead of checking the state of the keyboard, mouse and touch, you could simply check game.control.isDown(‘action a’) . Moreover, you should be able to redefine the input commands.


Particles are so so so so cool! Creatine uses the cocos2d particle style. So if you want to create some fire you do:

var emitter = null;

var game = new tine.Game(null, {
  preload: function() {
    game.load.image('particle', 'assets/particle_red.png');

  create: function() {
    var image = game.create.bitmap('particle', {regX:'center', regY:'center'});
    emitter = new tine.Emitter(image, 500);
    emitter.emitX = 512;
    emitter.emitY = 288;
    emitter.angle = -90;
    emitter.angleVar = 10;
    emitter.speed = 100;
    emitter.speedVar = 20;
    emitter.life = 2000;
    emitter.lifeVar = 500;
    emitter.emissionRate = 150;
    emitter.startScale = 0.3;
    emitter.compositeOperation = 'lighter';

  update: function() {

    if (game.mouse.isDown(tine.buttons.LEFT)) {
      emitter.emitX = game.mouse.x;
      emitter.emitY = game.mouse.y;


Unfortunately, the current particle system has some limitations. For example, it cannot change the particle colors due to performance. It also must be updated manually, sometimes I forget that!

Sounds and Storage

The SoundManager is simpler now, it does not separate music from sound effects, but you still can add sound groups to it. The coolest thing is that sound works together with the StorageManager, so when you change the volume or the mute, the sound manager stores this information locally and you don’t have to worry about that anymore!

Legacy Stuff

Some things will be changed to a better structure, such as the layout managers and the custom display objects. They are still in creatine but they weren’t updated this time.

Moar of Creatine

To now more about new stuffs in creatine, check it out:

You can also contact me for any doubt or suggestion.

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The 32th ludum dare happened this weekend (April 16, 2015), with the theme “unconventional weapon“.


I have have to say that I hate this theme. Really, there were so many good themes there, why this one could win? Damn you!!!! The theme isn’t an excuse to not do a game, but I spent so much time thinking of what I could do with this… A game not based on fights? Weapon is love? The weapon must be abstract! This is clichê? Oh damn… I finally came up with an idea, after 14 hours (counting sleep time)!

My game entry is about “democracy”, with quotes. The democracy and progress are the weapon of the government in the game, they want you to attack other species in order to “spread democracy and progress through the galaxy”. The player controls the invasions to planets inhabited by bugs with the goal to kill the natives and collect the planet resources.

The game is a very humble tribute to starship troopers (novel by Robert Heinlein and film by Paul Verhoven and Edward Neumeier). I wanted to create, somehow, the sense of order and progress presented by movie.


I always start by the core mechanics because it is the main component of the game – if I can’t find time to make graphics, at least I have a block-based game.

I also always wanted to create a game in a circular world, that was my excuse. I had no idea how to do that, but at is was pretty simple. You have a world centered at (0, 0) with radius (r), than you can set the origin of all objects in the world to (0, r) and only manipulate the rotation to place than in the world.

After the basic world structure, I could drop structures, and these structures could create units. To control the units, I created a behavior tree to control each unit – the first time I really use behavior3js – and a behavior tree to control the bugs strategy. Figure below show these behaviors trees:

Behavior tree for player and enemy units.

Behavior tree for player and enemy units – Click to see in full size.

Behavior tree for the nests, its used to create orders to enemy units

Behavior tree for the nests, its used to create orders to enemy units – Click to see in full size.

Then it came to particles and easing! Man, I love these two. The animation below shows the game at this point:

Sample of democracy

After 28 hours I started to create the sprites and visual things in the world. I was stupid enough to lost time adding some details to sprites that don’t even will see because the sprites are very small (about 20 pixels). I also spend a good time trying to create a futurist screen aspect, which ended up very cool.

I added some scenes, UI and some other effects to the graphics:


When the clock marked 5 hours to end the competition I started create sounds effects and music. I was desperate because of the time, I still had to adjust the levels of my game and I didn’t know what to do with sounds. At the end it was pretty simple and I didn’t do much, actually recorded some sounds with Audacity, generated most of them in BFXR and generated the music in SoundHelix.

I finished the game in the packing hour, the extra hour after 48, the time to deploy and write about your game.


Good stuff:

  • Game finished is always good!
  • I’m using BTs successfully, even to control hundreds of creatures.
  • A circular world (always wanted to try).
  • Visually smooth and lot of cool PARTICLES!!!!!
  • Generative music and sounds worked well.

Bad stuff:

  • Balancing is hard as hell, I couldn’t do that properly.
  • Some details missing, especially the visual feedback when you win the game and the bug when restarting a level before a tween is complete.
  • Isn’t much fun due to balance, few types of units, and few levels.

I’m very critic about my games, I really fell for to not balance properly and create more content to the game, but well, it was made in 48 hours and this time the good stuff was really good! Moreover, this was the most complex and complete game I ever made for LD, it was really hard to do, thus of course some things would be missing.



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So, I finally decided what to do for this ludum dare, which has the theme “unconventional weapon“. My weapon of choice is “Democracy“, a humble tribute to Heinlein’s novel – and, of course, the Verhoeven’s movie – Starship Troopers.

Player controls an invasion operation at a distant planet, inhabited by big insects , in order to spread “democracy” through the galaxy. The player must exterminate the insects and collect the planet resources to win.

This is what looks like for now:


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Just for the record, I hate the theme of LD 32, “unconventional weapon”. There were a bunch of good themes on the final voting round, like “grow”, “companion” and “abandoned”, but they have lost for “unconventional weapon”, gosh…

Well, we have to do what we have to do. The theme is what it is and now I have to use it. Unfortunately, I’m writing these after 2:30 hours of brainstorming and I still have no clue of what to do.

I really want to use AI, so I trying to add some agents (enemies, allies, creatures, companions, whatever), and giving my artistic and resource limitation, I thinking in use tile maps. That’s all I got for now and it may be useless tomorrow.

I’ll keep you updated.

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