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12. September 2014

 

 

Apparently on September the 9th Phaser 2.1 was released  followed quickly by the ohhhh oops Phaser 2.1.1 hotfix release.  It is important to note that this releasePhaser Logo has some code breaking changes in it, so read carefully before upgrading to see how your code might be impacted!

 

 

The release notes:

 

Version 2.1.1. of Phaser is an emergency point release. It addresses a potential race condition that could happen in States that tried to change state from the create method but had an empty preloader or pre-cached assets.

The list of changes below are from 2.1.0 - 9th September 2014

 
New Features
  • Updated to p2.js 0.6.0 - this was an API breaking change, so please see the p2.js section of this change log specifically if you're using p2 in your game.
  • If you are using CocoonJS, please set your game render type to CANVAS and not WEBGL or AUTO. You should also disable any of the ScaleManager screen resizing or margin setting code. By default in this mode CocoonJS will now set 'screencanvas=true' which helps with performance significantly.
  • Ninja Physics is no longer included in the build files by default. Not enough people were using it, and not enough contributions were coming in to help polish it up, so we've saved the space and removed it. It's still available in the grunt build files if you require it, but we're deprecating it from the core library at this time. It will make a return in Phaser3 when we move to a modular class system.
  • ScaleManager has a new scaleMode called RESIZE which will tell Phaser to track the size of the parent container (either a dom element or the browser window if none given) and set the canvas size to match it. If the parent changes size the canvas will resize as well, keeping a 1:1 pixel ratio. There is also a new ScaleManager.setResizeCallback method which will let you define your own function to handle resize events from the game, such as re-positioning sprites for a fluid responsive layout (#642)
  • The width and height given to the Phaser.Game constructor can now be numbers or strings in which case the value is treated as a percentage. For example a value of "100%" for the width and height will tell Phaser to size the game to match the parent container dimensions exactly (or the browser window if no parent is given). Equally a size of "50%" would tell it to be half the size of the parent. The values are retained even through resize events, allowing it to maintain a percentage size based on the parent even as it updates.
  • Device will now detect for Kindle and PS Vita (thanks @lucbloom)
  • Device will now detect for Cordova (thanks @videlais #1102)
  • Arcade Physics Body.skipQuadTree is a new boolean that if set to true when you collide the Sprite against a Group it will tell Phaser to skip using a QuadTree for that collision. This is handy if this Body is especially large.
  • Arcade Physics World.skipQuadTree will disable the use of all QuadTrees in collision methods, which can help performance in tightly packed scenes.
  • Cordova 'deviceready' event check added (thanks @videlais #1120)
  • Loader.useXDomainRequest boolean added. If true (the default is false, unless the browser is detected as being IE9 specifically) it will use XDomainRequest when loading JSON files instead of xhr. In rare IE edge-cases this may be required. You'll know if you need it (#1131 #1116)
  • Added support for Tiled objects type field (thanks @rex64 #1111)
  • Tile properties are now copied from the Tiled JSON data to the Phaser.Tile objects when parsed (thanks @beeglebug #1126)
  • All Images now have a frameData value, even if it's only one frame. This removes lots of engine code needed to check if images are sprite sheets or not, and simplifies game code too (thanks @lucbloom #1059)
  • Added a new Phaser.Rope object. This allows for a series of 'chained' Sprites and extends the Rope support built into Pixi. Access it via game.add.rope (thanks @codevinsky #1030)
  • Phaser.Device.isAndroidStockBrowser will inform you if your game is running in a stock Android browser (rather than Chrome) where you may wish to scale down effects, disable WebGL, etc (thanks @lucbloom #989)
  • Phaser.Camera has a new property position which is a Point object that allows you to get or set the camera position without having to read both the x and y values (thanks @Zielak#1015)
  • TileSprite now has the alive property, which should help with some Group operations (thanks @jonkelling #1085)
  • Events.onDestroy is a new signal that is dispatched whenever the parent is being destroyed. It's dispatched at the start of the destroy process, allowing you to perform any additional house cleaning needed (thanks @jonkelling #1084)
  • Group.onDestroy is a new signal that is dispatched whenever the Group is being destroyed. It's dispatched at the start of the destroy process, allowing you to perform any additional house cleaning needed (thanks @jonkelling #1084)
  • ScaleManager.destroy now removes the window and document event listeners, which are no longer created anonymously (thanks @eguneys #1092)
  • Input.Gamepad.destroy now destroys all connected SinglePads and clears event listeners.
  • SinglePad.destroy now clears all associated GamepadButton objects and signals.
  • Device.node and Device.nodeWebKit are two new properties (thanks @videlais #1129)
  • P2.PointProxy.mx and my values are get and set in meters with no pixel conversion taking place.
  • P2.InversePointProxy.mx and my values are get and set in meters with no pixel conversion taking place.
  • Pointer.dirty is a new boolean that is set by the InputHandler. It tells the Pointer to re-check all interactive objects it may be over on the next update, regardless if it has moved position or not. This helps solve issues where you may have a Button that on click generates a pop-up window that now obscures the Button (thanks @jflowers45 #882)
  • SoundManager.destroy is a new method that will destroy all current sounds and reset any callbacks.
  • StateManager.clearCurrentState now handles the process of clearing down the current state and is now called if the Game is destroyed.
  • Game.destroy now clears the current state, activating its shutdown callback if it had one. It also now destroys the SoundManager, stopping any currently running sounds (#1092)
  • Animation.onUpdate is a new event that is dispatched each time the animation frame changes. Due to its intensive nature it is disabled by default. Enable it withAnimation.enableUpdate = true (#902)
  • Device now has new features to support detection of running inside a CocoonJS.App (thanks@videlais #1150)
  • Support for CocoonJS.App's 'onSuspended' and 'onActivated' events, making it so that the timers and sounds are stopped/started and muted/unmuted when the user swaps an app from the background to the fore or the reverse (thanks @videlais #1152)
  • Canvas.removeFromDOM(canvas) will remove a canvas element from the DOM.
  • Game.destroy now removes the games canvas element from the DOM.
  • ScaleManager.setMinMax(minWidth, minHeight, maxWidth, maxHeight) is a handy function to allow you to set all the min/max dimensions in one call.
  • ArcadePhysics.collide and overlap can now accept 2 Arrays of objects to be used in the collision checks (thanks @ctmartinez1992 #1158)
  • RetroFont has a new property called frameData which contains the Frame objects for each of the letters in the font, which can be used by Sprites.
  • Phaser.Canvas.setImageRenderingCrisp now sets image-rendering: pixelated, perfect for pixel art, which is now supported in Chrome 38.
  • Phaser.Mouse will now add a listener to the window to detect mouseup events. This is used to detect if the player releases the mouse while outside of the game canvas. Previously Pointer objects incorrectly thought they were still pressed when you returned the mouse over the canvas (#1167)
  • Rectangle.centerOn(x,y) allows you to quickly center a Rectangle on the given coordinates.
  • Group.addMultiple allows you to pass an array of game objects and they'll all be added to the Group in turn.
  • The StateManager will now check if a State has a method called resize. If it does, and if the game is running in the RESIZE Scale Mode then this method will be called whenever the game resizes. It will be passed two parameters: width and height that will match the games new dimensions. Resizing can happen as a result of either the parent container changing shape, or the browser window resizing.
  • Rectangle.topRight returns a Point object that represents the top-right coordinate of the Rectangle.
  • The grunt script now builds a new version of Phaser without any physics (including Arcade Physics), Tilemaps or Particles. This build is called phaser-no-physics.js and works stand-alone. Please note that things like the GameObjectFactory aren't changed, so they will still try and create a Tilemap for example should you ask them to (thanks @eguneys #1172)
  • Camera.roundPx is a new boolean. If set to true it will call view.floor as part of its update loop, keeping its boundary to integer values. Set to false to disable this from happening (#1141)
  • Phaser.Easing.Default is a new property that is used when a specific type of ease isn't given. It defaults to Linear.None but can be overridden to anything (thanks @alvinsight)
 
Updates
  • TypeScript definition updates to help fix for the noimplicitany option (thanks @Waog#1088)
  • TypeScript definitions fixes and updates (thanks @clark-stevenson @englercj @saikobeeand @rhmoller)
  • All of the Pixi geom classes have been removed from the build file as they aren't needed (the Phaser.Geom classes overwrite them), saving some space in the process.
  • Improved consistency of clone methods on geometry classes (thanks @beeglebug #1130)
  • Removed Cache.isSpriteSheet method as no longer required (see #1059)
  • Added Cache.getFrameCount to return the number of frames in a FrameData.
  • Input.setMoveCallback has been removed due to deprecation.
  • BitmapData.refreshBuffer has been removed and replaced with BitmapData.update.
  • BitmapData.drawSprite has been removed due to deprecation. Use BitmapData.draw instead.
  • Pointer.moveCallback has been removed due to deprecation.
  • SinglePad.addButton has been removed due to deprecation.
  • P2.Body.loadData has been removed due to deprecation.
  • P2.World.defaultFriction and defaultRestitution have been removed due to deprecation.
  • Canvas.create noCocoon parameter has been removed due to deprecation.
  • Color.getColorInfo, RGBtoHexstring, RGBtoWebstring and colorToHexstring has been removed due to deprecation.
  • P2.PointProxy.x and y values are now returned in pixels (previously they were returned in meters). See PointProxy.mx/my for meter values.
  • P2.InversePointProxy.x and y values are now returned in pixels (previously they were returned in meters). See PointProxy.mx/my for meter values.
  • Arcade.overlap and collide are now more consistent about allowing a Group vs. Group or Group vs. Array of Groups set (thanks @pyromanfo #877 #1147)
  • The Pointer move callbacks are now sent an extra parameter: fromClick allowing your callbacks to distinguish between the Pointer just moving, or moving as a result of being pressed down (thanks @iforce2d #1055)
  • GamePad and SinglePad onAxisCallback parameters have changed. You are now sent: this (a reference to the SinglePad that caused the callback), the axis index and the axis value in that order.
  • If Time.elapsed was > Time.timeCap it would reset the elapsed value to be 1 / 60. It's now set to Time.timeCap and Time.timeCap defaults to 1 / 60 * 1000 as it's a ms value (thanks@casensiom #899)
  • Tiled polylines are now imported into the map objects property as well as map collision (#1117)
  • Tile.setCollision now adjusts the tiles interesting faces list as well, this allows you to create one-way jump tiles without using custom callbacks on a specific tile basis (thanks@RafaelOliveira #886)
  • Stage.offset has been moved to ScaleManager.offset
  • Stage.bounds has been removed, you can access it via Stage.getBounds.
  • Stage.checkOffsetInterval has been moved to ScaleManager.trackParentInterval
  • ScaleManager.hasResized signal has been removed. Use ScaleManager.setResizeCallback instead.
  • The World bounds can now be set to any size, including smaller than the game dimensions. Before it was locked to a minimum size of the game canvas, but it can now be anything.
  • ScaleManager.orientationSprite has been removed because it never displayed correctly anyway (it would be distorted by the game scale), it will be bought back in a future version by way of a custom orientation state.
  • ArcadePhysics.overlap has been updated so that the Body.overlapX/Y properties are set to the amount the two bodies overlapped by. Previously they were zero and only populated during the separation phase, but now the data is available for just overlap checks as well. You can then use these values in your ovrelap callback as required - note that they are changed for every check, so a Sprite overlap tested against 10 other sprites will have the overlapX/Y values updated 10 times in a single collision pass, so you can only safely use the values in the callback (#641)
  • Cache.getImage now returns null if the requested image wasn't found.
  • BitmapData now returns a reference to itself from all of its drawing related methods, allowing for easy function chaining.
  • The default size of a BitmapData if no width/height is given has been changed from 100x100 to 256x256.
  • Phaser.Text.destroy will now destroy the base texture by default (#1162)
  • BitmapData.copyPixels is now called BitmapData.copyRect and the method signature has changed.
  • BitmapData.draw method signature has changed significantly.
  • Phaser.Canvas.getSmoothingEnabled will return true if the given context has image smoothing enabled, otherwise false.
  • Math.numberArrayStep is a new method that allows you to return an array of numbers frommin to max including an optional step parameter (thanks @codevinsky #1170)
  • Removed redundant if check from StateManager.preUpdate (thanks @FedeOmoto #1173)
 
Bug Fixes
  • Remove escaping backslashes from RetroFont text set documentation (thanks @jackrugile#1051)
  • Phaser.Loader was incorrectly getting the responseText from _xhr instead of _ajax on IE9 xDomainRequests (thanks @lardratboy #1050)
  • Phaser.Physics.P2.addPolygon now takes a nested array again (thanks @wayfu #1060)
  • Fix for previous PR #1028 where the P2.setBoundsToWorld call was overriding setBoundsToWorld in the P2 constructor (thanks @Dumtard #1028)
  • Fix for scale issues in CocoonJS using webgl renderer and screencanvas (thanks@txusinho #1064)
  • Resolves issue with pixel perfect click / over detection on Sprites that used trimmed image atlases for animations or frames > 0.
  • Group.swap() updates the Z index values properly (thanks @Blank101 #1090)
  • Device now recognises ChromeOS as a desktop (thanks @alvinsight @hilts-vaughan#1091)
  • Fixed Point.rotate bug (thanks @gamedolphin #1107)
  • InputHandler.checkBoundsRect was incorrectly assigning a property in Sprites fixed to the camera being dragged left (thanks @CraigBeswetherick #1093)
  • Swapped argument order of Rectangle.containsRect (thanks @beeglebug #1095 #1125)
  • The Game configuration object "renderer" property was being wrongly assigned to Game.renderer instead of renderType (thanks @FedeOmoto #1127)
  • Fixed Group.removeBetweens default endIndex (thanks @darfux #1142)
  • Debug.cameraInfo no longer crashes if the camera bounds are nulled (thanks @wayfu#1143)
  • Camera.setBoundsToWorld no longer crashes if the camera bounds are nulled (thanks@wayfu #1143)
  • Fixed the resolution uniform type in the SampleFilter (thanks @VictoryRice #1137)
  • Calling P2.Body.destroy or ArcadePhysics.Body.destroy wouldn't null the parent sprite body, causing it to error in the next update (thanks @jonathanhooker #1077)
  • BitmapFonts are now correctly added to the Cache._bitmapFont array and returned via Cache.getBitmapFont (thanks @prudolfs #1076)
  • InputHandler docs updated to avoid Pointer data-type confusion (#1097)
  • If you used a single Game configuration object and didn't specify the enableDebug property it would crash on Debug.preUpdate (thanks @luizbills #1053)
  • The P2.World.postBroadphaseHandler now checks if the returned pairs array is empty or not before processing it (thanks @wayfu #934)
  • Tilemap.hasTile now checks the Tile.index value and will return false if the index is -1 (i.e. a non-active tile) (thanks @elgansayer #859)
  • Sound.restart used to cause the Sound to double-up if it was already playing when called. Now correctly stops the sound before restarting it (thanks @wombatbuddy #1136)
  • GamePad axis detection now works again properly in Firefox (#1035)
  • GamepadButton.justPressed and justReleased now correctly report if the button has just been pressed or released (thanks @padpadpad #1019)
  • TilemapParser.getEmptyData now correct adds an empty bodies array into layers. This fixes an issue where p2 couldn't convert a csv map into collision tiles (thanks @sru #845)
  • CocoonJS doesn't support mouse wheel events so they've been moved into a conditional check (thanks @videlais #1151)
  • ScaleManager window.resize handler would constantly dispatch enterPortrait and enterLandscape events on window resizing, regardless if it actually entered that orientation or not.
  • Added Sound._muteVolume which stops Firefox and IE9 crashing if you try to unmute a sound that hasn't yet been muted, which can also happen as a result of a game visibility change (thanks @osmanzeki #1108 #1123)
  • P2.World.getSprings used to return an empty array, but now returns all the Springs in the world (#1134)
  • Tween.generateData would skip the end values in the data array. They are now included as the object in the final array element.
  • Rectangle.bottom setter swapped the order of the calculation (thanks @JakeCoxon #1165)
  • Phaser.Text wouldn't render the text to its local canvas if you passed the text on the constructor and didn't add it to the display list. If a string is given it now updates the local canvas on creation.
  • Signal.removeAll would ignore the context parameter and remove all bindings regardless (thanks @alect #1168)
  • P2.Body.addCapsule didn't use to pass the radius value through pxm, but now does so you have to specify it in pixels, not meters.
 
p2.js 0.6.0 Changes and New Features
  • DistanceConstraint signature changed to take the new localAnchors.
  • World.createDistanceConstraint signature changed to include new local anchors (thanks@rhmoller #1169)
  • RevoluteConstraint signature changed to include worldPivot.
  • P2.Body now uses the new Body.type value instead of Body.motionState, however as P2.Body already have a property called type we have left the motionState getter/setter in for now.
  • World.enableBodySleeping has been removed and replaced with World.sleepMode.
  • Phaser P2.Springs are now LinearSprings by default.
  • World.createRotationalSpring will now let you create rotational springs.
 
Breaking changes
  • Renamed property .motionState to .type in class Body.
  • Changed constructor of RevoluteConstraint. Now the local pivots are passed as options instead of direct arguments. See the constraints demo.
  • Removed World.prototype.toJSON and .fromJSON.
  • Removed properties .enableBodySleeping and .enableIslandSleeping from World instances. The enum .sleepMode can be used instead. See the sleep demo.
  • Converted Spring to a base class for the new LinearSpring and RotationalSpring classes. LinearSpring can be used as the old Spring.
  • Utils.ARRAY_TYPE can now be overridden by injecting a global called P2_ARRAY_TYPE. Support for GLMAT_ARRAY_TYPE has been removed.
 
Other changes
  • Added flag .enableFrictionReduction to Narrowphase.
  • Added RevoluteConstraint.prototype.setLimits.
  • Added PrismaticConstraint.prototype.setLimits.
  • LockConstraint, DistanceConstraint, and GearConstraint can now be constructed from current body transforms.
  • RevoluteConstraint can now be constructed from the current body transforms and a world point.
  • Material id can now be passed via constructor.
  • ContactMaterial instances now have a property .contactSkinSize.
  • Added method Body.prototype.getAABB.
  • Limits for DistanceConstraint. See the DistanceConstraint demo.
  • Added Body.prototype.overlaps.
  • Added class OverlapKeeper.
  • If substepping is used in World.prototype.step, the substeps are aborted if slower than real time.
  • Added Heightfield/Convex and Heightfield/Circle collision support.
  • Added property .overlapKeeper to World.
  • EventEmitter.prototype.has can now check if any listeners were added to a given topic.
  • Added Utils.defaults.

 

In reading through the changes, I do not believe any of the GameFromScratch Phaser tutorial series will be impacted if you use the newest version.

News


12. September 2014

 

I just received the following announcement from the Cocos2D team, which oddly is not yet on their site.  There has been a new release of the seminal Cocos2D library, as well as a new version of the SpriteBuilder tool.

 

SpriteBuilder 1.2 and Cocos2D 3.2 are here!

 

image

 


We are pleased to announce the launch of brand new versions of SpriteBuilder and Cocos2D-Swift! The biggest news in the 1.2 version of SpriteBuilder (change log) is the addition of the packages feature. Packages give you greater control over how you can share SpriteBuilder content, including images, audio files, and more. It allows you to group resources together and to export or import them as a single unit for ease of management. This is great if you want to share elements used in your game, either between your own projects or with the SpriteBuilder community. We're working on packages support in Cocos2D 3.3 that will make this feature even more useful for game developers, so stay tuned!

 


Cocos2D 3.2 adds the new and exciting CCEffects API, which allows you to add blurs, color, reflections, and many other cool effects to your sprites with only a single line of code! Check out our latest blog post for more details on CCEffects.

 


Cocos2D 3.2 also introduces a change to project templates that will streamline and simplify developer workflow. In effect, SpriteBuilder is now the official way to generate Cocos2D projects, as the Cocos2D-specific Xcode templates have been removed. This change makes it easier to upgrade projects to later versions of Cocos2D and eliminates a code path that was difficult to maintain and test. SpriteBuilder is free and open source as well as being the official IDE for Cocos2D, but it's not required for use with a Cocos2D codebase beyond the project creation step.

 

image


Download SpriteBuilder from the Mac App Store (includes Cocos2D-Swift) ›

 


Learn more about SpriteBuilder on our community forum!

 

Cocos2D is an open source 2D game framework for building games with Objective C and XCode.  You can download it here.

News


8. September 2014

 

The following is a guest tutorial by Avetis showing how to use LibGDX and Overlap2D to create an Angry Birds like game.  Overlap2D is a level and UI editor handy for separating game coding from content creation.  Keep in mind, Overlap2D is fairly young, currently at 0.0.4 version. Now, on with the tutorial!

 



Making Flappy Bird with Overlap2D – Overlappy Tutorial

 

 

Agenda


In this tutorial we are going to create a FlappyBird clone game (for learning purposes only) using Java, LibGDX framework and accelerate it all by moving our UI, Level, and Asset management into Overlap2D Editor. One thing I figured while coding is that you can’t make a quick tutorial about a flappy bird clone, ever. It’s going to be long if we want details. It is easier though to use the explain approach instead of step by step guide.  So I am going to share all the sources and resources, and then go with you through setting this all up, show how things work, and hopefully this all will make sense.

 

Prerequisites


Java knowledge, basic LibGDX experience, computer, time. Make sure you use latest Overlap2D editor and runtimes (v 0.0.4 or higher)

Get latest LibGDX project setup here: http://bitly.com/1i3C7i3 ( Details here )
Get latest Overlap2D editor here: http://overlap2d.com

 

First - Get Game Assets (Resources)


First let’s download the assets. I made a small pack of images I found on the internet with Flappy Bird images, animations and font. You can get it here: http://overlap2d.com/?p=236

 

 

Setting up Your Overlap2D Project

 

Unzip your Overlap2D zip file, and run the Overlap2D.jar.


First things first, you are currently viewing demo project, so go to File and Create New Project. Call it OverlappyBird and then create the scene size, let it be 480 width, 800 in height. It’s a standard small mobile device resolution, and since Flappy Bird is a portrait game, it should be just right. Click Create Project.
You have now created an empty project and it’s ready for setup, now you need to import the assets. Here we have 3 types of assets, first is just image textures, and second is a sprite animation for bird itself, and lastly the TTF font for score label. I have separated them in folders so you can import easily. Click on File, import to library.


First click on “…” button near the import images text field to select your images; locate them, select all. When done click on import and they all will get imported to your assets area on the right middle panel. Then open same the dialog again, and this time find Import Sprite Animations (note: not spine, but sprite) Click on “…” button there and locate bird.atlas file. Click Import, and it will get added to your assets list as well.


Lastly open import dialog again, and import font, by locating ttf file.


Your project setup is ready.

 

Making The Main Scene

 

First let’s see how main scene looks in Overlap2D when it is finished:

 

image


 
I decided to make several layers to have things organized, bg layer for background image that is not moving, default layer for pipes and bird itself, ground layer for moving the ground that is covering pipes, ui layer for “get ready” popups and score labels, and finally dlg layer for end game dialog. The reason I am not putting dialog inside ui layer is that I can position it in its layer correctly, and later hide that layer so it will not intervene with my work.  So, go ahead and create this layers in the order I described from bottom to top. (bg layer goes below them all, and you can rearrange them by drag-and-dropping)


I also recommend you to open my example project (provided with resources). Open it with Overlap2D and see how things are positioned and grouped. (To open a project, click file, open, and then locate .pit file inside project.)


Compose your own project like I did,. Put background on bg layer, and add bird on default layer. Make sure it looks like the picture above.


The ground is going to be a moving part, so we need to have 2 of this near each other for seamless movement. Put two grounds near each other and then group them into composites, like on this picture, do not forget to give identifier to it for later use.


image

 

For the pipes we are going to do the following trick. First of all we are going to put pipes on top of each other with a gap, and convert them into composite, and then add to library to have kind of a prefab for a pipe column. Later in code we are going to pre-load 3 of this because there is never more than 3 columns of pipes visible on screen, so we can re-use the ones that are left of the screen for next pipe iteration.


image


Now some of the pipes are going to vary in position on Y axis. So there are a minimum and maximum values that it should not be below or above. To avoid having this values in code, I just put 2 of pipe columns on screen: one at the lowest point and the other at the highest, and give them identifiers in order to read those values from code later.

 

image

 

Next click on bird in properties box and add 2 custom variables, by clicking on custom variables button. First is jump_speed=400, and second is gravity=1000 (so you can later tweak game from editor not from code)


image

 

Next up, put a “hint” and “get ready” assets convert them into composite as they always go together and give them id to hide show from game. They should go to ui layer.

 

Making Menu Scene

 

This one is easier: click on File, Scenes, Create New Scene, and choose MenuScene as name.


Make sure to put up all things just like on this picture. And note that you should make a composite for ground agai n (as we do not yet share prefabs between the scenes).


Put a Play button as image and give it an id to add listeners later in your code.


Here is how it should look:

 

image

 

Overlap2D Part DONE!


Looks pretty good! Both scenes are set up and ready for some coding. Most importantly your scene and UI are very flexible and code-independent.

 

 

 

Setting up LibGDX Project and Getting Ready to Code:

 

Download the LibGDX setup application and setup an empty project (make sure to have checked box2d and freetype fonts), import it to your eclipse or other IDE, run the desktop app to make sure it works, then strip it from LibGDX picture  and make it just a black screen.


Make sure your desktop launcher has code to specify screen size of 480x800 (config variables in launcher).


We are going to render everything using a simple LibGDX Stage, so the code structure will be the following: GameStage extending Stage that will load all the Overlap2D data and display it; Main class that will be rendering GameStage in its render method.


For all the rest we are going to use iScript functionality of Overlap2D. Let me go a bit in depth for that. Overlap2D runtime provides an interface that you can implement to create a “brain” of any composite item. Basically it is your way of attaching logic to an object. In this example we are going to create 3 iScripts, one is going to get attached to entire mainScreen and be a GameScreenScript with all game logic, other will be MenuScreenScript for menu, and the last one will be BirdScript that we will attach to the bird. It is important to mention that you cannot attach script to an image, or sprite animation, so I have converted bird animation to composite item in order to do it (right click, convert into composite).

 

You can find the full project on my github:  https://github.com/azakhary/OverlappyBird

Here are the well commented sources:

 

OverlappyBird.java

package com.underwater.demo.overflappy;

import com.badlogic.gdx.ApplicationAdapter;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;

/*
 * This is our ApplicationListener the main thing that things start in libGDX
 */
public class OverflappyBird extends ApplicationAdapter {
   
   /*
    * GameStage will be holding both menu and main game
    */
   private GameStage stage;
   
   @Override
   public void create () {
      stage = new GameStage();
   }

   @Override
   public void render () {
      // Clearing the screen before each render
      Gdx.gl.glClearColor(0, 0, 0, 1);
      Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
      
      // calling stage act method and passing delta time passed since last call
      stage.act(Gdx.graphics.getDeltaTime());
      // drawing all actors
      stage.draw();
      
   }
}

GameStage.java

package com.underwater.demo.overflappy;

import java.io.File;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.scenes.scene2d.Stage;
import com.uwsoft.editor.renderer.DefaultAssetManager;
import com.uwsoft.editor.renderer.SceneLoader;

/*
 * GameStage 
 */
public class GameStage extends Stage {
   
   // Speed of pixels per second of how fast things move left (required both for 
                                                               menu and the game,
                                                               thus put here)
   public float gameSpeed = 200;

   // Overlap2D  provides this easy asset manager that loads things as they are 
   provided by default when exporting from overlap
   private DefaultAssetManager assetManager;
   
   public GameStage() {
      super();
      
      // Set this is input processor so all actors would be able to listen to 
      touch events
      Gdx.input.setInputProcessor(this);
      
      // Initializing asset manager
      assetManager = new DefaultAssetManager();
      
      // providing the list of sprite animations which is one in this case, to 
      avoid directory listing coding
      assetManager.spriteAnimationNames = new String[1]; assetManager.
                                          spriteAnimationNames[0] = "bird";
      
      // loading assets into memory
      assetManager.loadData();
      
      // Menu goes first
      initMenu();
   }
   
   public void initMenu() {
      clear();
      
      // Creating Scene loader which can load an Overlap2D scene
      SceneLoader menuLoader = new SceneLoader(assetManager);
      
      // loading MenuScene.dt from assets folder
      menuLoader.loadScene(Gdx.files.internal("scenes" + File.separator + 
                           "MenuScene.dt"));
      
      // Initializing iScript MenuSceneScript that will be holding all menu 
      logic, and passing this stage for later use
      MenuScreenScript menuScript = new MenuScreenScript(this);
      
      // adding this script to the root scene of menu which is hold in 
      menuLoader.sceneActor
      menuLoader.sceneActor.addScript(menuScript);
      
      // Adding root actor to stage
      addActor(menuLoader.sceneActor);
      
      
   }
   
   public void initGame() {
      clear();
      
      // Creating Scene loader which can load an Overlap2D scene
      SceneLoader mainLoader = new SceneLoader(assetManager);
      
      // loading MainScene.dt from assets folder
      mainLoader.loadScene(Gdx.files.internal("scenes" + File.separator + 
                           "MainScene.dt"));
      
      // Initializing iScript GameSceneScript that will be holding all game, and 
      passing this stage for later use
      GameScreenScript gameScript = new GameScreenScript(this, mainLoader);
      
      // adding this script to the root scene of game which is hold in 
      mainLoader.sceneActor
      mainLoader.sceneActor.addScript(gameScript);
      
      // Adding root actor to stage
      addActor(mainLoader.sceneActor);
   }

}

GameScreenScript.java

package com.underwater.demo.overflappy;

import java.util.ArrayList;

import com.badlogic.gdx.math.MathUtils;
import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.scenes.scene2d.InputEvent;
import com.badlogic.gdx.scenes.scene2d.Touchable;
import com.badlogic.gdx.scenes.scene2d.actions.Actions;
import com.badlogic.gdx.scenes.scene2d.actions.AddAction;
import com.badlogic.gdx.scenes.scene2d.utils.ClickListener;
import com.uwsoft.editor.renderer.SceneLoader;
import com.uwsoft.editor.renderer.actor.CompositeItem;
import com.uwsoft.editor.renderer.actor.LabelItem;
import com.uwsoft.editor.renderer.script.IScript;

/*
 * iScript for entire game logic
 */
public class GameScreenScript implements IScript {
   
   /*
    * reference to GameStage
    */
   private GameStage stage;
   
   /*
    * Main actor that holds root of game screen
    */
   private CompositeItem game;
   
   // Screen loader reference to be later used to retrieve prefabs from library
   private SceneLoader loader;
   
   // Game over Dialog actor
   private CompositeItem gameOverDlg;
   
   /*
    * this will be holding 2-ground system composite item 
    */
   private CompositeItem groundRotator;
   
   /*
    * Instead of holding bird actor we are going to hold birdscript that will 
    provide all bird logic and methods.
    * Also it will have bird actor inside
    */
   private BirdScript bird;
   
   // Hint Box actor the one that shown in begining of game
   private CompositeItem hintBox;
   
   // some helping booleans
   private boolean gameStarted = false;
   private boolean groundStop = false;
   
   // going to hold what is the possible low and high position for a pipe column
   private float minPipe;
   private float maxPipe;
   
   private int gameScore = 0;
   private LabelItem scoreLbl;
   
   // Going to hold 3 pipes here to reuse as pipe pool
   private ArrayList<CompositeItem> pipes = new ArrayList<CompositeItem>();
   
   public GameScreenScript(GameStage stage, SceneLoader loader) {
      this.stage = stage;
      this.loader = loader;
   }
   
   @Override
   public void init(CompositeItem gameItem) {
      game = gameItem;
      
      gameScore = 0;
      
      // Creating and holding BirdScript that will hold entire bird logic.
      bird = new BirdScript(stage);
      game.getCompositeById("bird").addScript(bird);
      
      groundRotator = game.getCompositeById("groundRotator");
      hintBox = game.getCompositeById("hintBox");
      scoreLbl = game.getLabelById("scoreLbl");
      
      // Adding listeners to listen for taps to make bird jump
      game.addListener(new ClickListener() {
         public boolean touchDown (InputEvent event, float x, float y, int 
                                   pointer, int button) {
            return true;
         }
         public void touchUp (InputEvent event, float x, float y, int pointer, 
                              int button) {
            // screen tap was done
            screenTap();
         }
      });
      
      // Loading min/max positions from level editor
      minPipe = game.getCompositeById("minPipe").getY();
      maxPipe = game.getCompositeById("maxPipe").getY();

      // Retrieving 3 pipe columns from library putting them into array,
      // and adding on screen in minus coordinates so the will becom "availible"
      for(int i = 0;  i < 3; i++) {
         CompositeItem pipe = loader.getLibraryAsActor("pipeGroup");             
         pipe.setX(-pipe.getWidth());        
         game.addItem(pipe);
         
         pipes.add(pipe);
      }
      
      
      // Making sure first pipe will be added not sooner then 3 seconds from now
      game.addAction(Actions.sequence(Actions.delay(3.0f), Actions.run(new 
                     Runnable() {
         
         @Override
         public void run() {
            putPipe();
         }
      })));
      
      // hiding game over dialog
      gameOverDlg = game.getCompositeById("gameOverDlg");
      // it should not listen for taps
      gameOverDlg.setTouchable(Touchable.disabled);
      gameOverDlg.setVisible(false);
   }

   @Override
   public void act(float delta) {
      
      // if game is not yet started or started (but most importantly not ended, 
                                                ground is moving) 
      if(!groundStop) {
         groundRotator.setX(groundRotator.getX() - delta * stage.gameSpeed);     
         if(groundRotator.getX() < -groundRotator.getWidth()/2) groundRotator.
            setX(0);
      }
      
      // if game is started, so first tap fone, then we dhould check for 
      collisions and move pipes
      if(gameStarted) {
         for(int i = 0; i < pipes.size(); i++) {
            // get pipe
            CompositeItem pipe = pipes.get(i);
            
            // move it if it has positive coordinate
            if(pipe.getX() > -pipe.getWidth()) {
               // if pipe was right of thebird, and will now become left of the 
               bird, add to score
               if(pipe.getX() >= bird.getBirdCenter().x && pipe.getX() - delta * 
                  stage.gameSpeed < bird.getBirdCenter().x) {
                  gameScore++;
               }
               pipe.setX(pipe.getX() - delta * stage.gameSpeed);
            }
            
            //check for collision with bird
            collisionCheck();
         }
      }
      
      // update scorel label
      scoreLbl.setText(gameScore+"");
   }
   
   /*
    * Check for bird versus pipe row collision
    */
   private void collisionCheck() {
      // iterate through all 3 pipes
      for(int i = 0; i < pipes.size(); i++) {
         CompositeItem pipe = pipes.get(i);
         
         // to make it easy going to think about bird as circle with 5 radius 
         Vector2 birdPoint = bird.getBirdCenter();
         
         // Is there collision? if yes stop the game and allow bird to fall
         if(birdPoint.x+5 > pipe.getX() && birdPoint.x - 5 < pipe.getX() + pipe.
            getWidth() && (pipe.getY() + 532 > birdPoint.y - 5 || pipe.getY()+
            701 < birdPoint.y + 5)) {
            stopGame(); 
         }
         
         // Did bird hit the ground? not only stop the game but also 
         // disable gravity to keep from further falling, and consider bird dead 
         ( animations stop )
         if(birdPoint.y-5 < groundRotator.getY()+groundRotator.getHeight()) {
            if(!groundStop) {
               stopGame();
            }
            bird.disableGravity();
            bird.getBird().setY(groundRotator.getY()+groundRotator.getHeight()+5)
                         ;
            // killitwithfire
            bird.die();
         }
      }
   }
   
   /*
    * Stops the game
    */
   private void stopGame() {
      gameStarted = false;
      groundStop = true;
      game.clearActions();
      
      // show end game dialog
      showEndDialog();
   }
   
   /*
    * showing end game dialog
    */
   public void showEndDialog() {
      // enabling touch back, showing
      gameOverDlg.setTouchable(Touchable.enabled);
      gameOverDlg.setVisible(true);
      // setting transparency to full
      gameOverDlg.getColor().a = 0;
      // and fading it in
      gameOverDlg.addAction(Actions.fadeIn(0.4f));
      
      // setting play button listener to replay the game
      gameOverDlg.getImageById("playBtn").addListener(new ClickListener() {
         public boolean touchDown (InputEvent event, float x, float y, int 
                                   pointer, int button) {
            return true;
         }
         public void touchUp (InputEvent event, float x, float y, int pointer, 
                              int button) {
            stage.initGame();
         }
      });
   }
   
   /*
    * Called when screen is tapped
    */
   private void screenTap() {
      // if ground is not moving then bird is dead no actin required on tapp
      if(groundStop) return;
      
      // if game started just jump the bird
      if(gameStarted) {
         bird.jump();
      } else {
         // if game is not yet started, start the game and jump the bird
         gameStarted = true;
         hintBox.addAction(Actions.fadeOut(0.3f));
         // and also enable gravity from now on
         bird.enableGravity();
         bird.jump();
      }
   }
   
   /*
    * get's availible pipe
    * availible pipe is any pipe that is left of screen and not visible
    */
   public CompositeItem getAvailablePipe() {
      for(int i = 0; i < pipes.size(); i++) {
         if(pipes.get(i).getX() <= -pipes.get(i).getWidth()) {
            return pipes.get(i);
         }
      }
      
      return null;
   }
   
   /*
    * this is called every X time to put a new pipe on the right
    */
   public void putPipe() { 
      // getting availible pipe
      CompositeItem pipe = getAvailablePipe();
      
      // when you die at bad moment, it can be null sometimes
      if(pipe == null) return;
      
      // put pipe column on the random hight from min to max range
      pipe.setX(stage.getWidth());
      pipe.setY(MathUtils.random(minPipe, maxPipe));
      
      // schedule next pipe to be put in 1.3 seconds
      game.addAction(Actions.sequence(Actions.delay(1.3f), Actions.run(new 
                     Runnable() {
         
         @Override
         public void run() {
            // call itself
            putPipe();
         }
      })));
   }

}

 

MenuScreenScript.java

 

package com.underwater.demo.overflappy;

import com.badlogic.gdx.math.MathUtils;
import com.badlogic.gdx.scenes.scene2d.InputEvent;
import com.badlogic.gdx.scenes.scene2d.utils.ClickListener;
import com.uwsoft.editor.renderer.actor.CompositeItem;
import com.uwsoft.editor.renderer.actor.ImageItem;
import com.uwsoft.editor.renderer.actor.SpriteAnimation;
import com.uwsoft.editor.renderer.script.IScript;

/*
 * iScript for menu logic
 */
public class MenuScreenScript implements IScript {
   
   /*
    * reference to GameStage
    */
   private GameStage stage;
   
   /*
    * this is the main root menu actor to work with
    */
   private CompositeItem menu;
   
   /*
    * this will be holding 2-ground system composite item 
    */
   private CompositeItem groundRotator;
   
   /*
    * this will be the bird sprite animation displayed in center of screen
    */
   private SpriteAnimation bird;
   
   // this variables are used to wiggle bird up and down with sin function
   private float iterator = 0;
   private float birdInitialPos;
   
   public MenuScreenScript(GameStage stage) {
      this.stage = stage;
   }

   public void init(CompositeItem menuItem) {
      menu = menuItem;
      
      // Finding playButton by id and storing in variable
      ImageItem playBtn = menuItem.getImageById("playBtn");
      
      // Finding ground composite and storing in variable 
      groundRotator = menuItem.getCompositeById("groundRotator");
      
      // Finding bird and storing in variable
      bird = menuItem.getSpriteAnimationById("bird");
      
      // let's remember where bird was initially
      birdInitialPos = bird.getY();
      
      // Adding a Click listener to playButton so we can start game when clicked
      playBtn.addListener(new ClickListener() {
         // Need to keep touch down in order for touch up to work normal (libGDX 
                                                                          awkward
                                                                          ness)
         public boolean touchDown (InputEvent event, float x, float y, int 
                                   pointer, int button) {
            return true;
         }
         public void touchUp (InputEvent event, float x, float y, int pointer, 
                              int button) {
            // when finger is up, ask stage to load the game
            stage.initGame();
         }
      });
   }
   
   /*
    * This is called every frame
    */
   public void act(float delta) {
      // moving ground left with game speed multiplied by delta as delta shows 
      what part of second was passed since last call
      groundRotator.setX(groundRotator.getX() - delta * stage.gameSpeed);     
      
      // if ground rotator got half way left, we can just put it back to 0, and 
      to eye it will look like it endlessly moves
      if(groundRotator.getX() < -groundRotator.getWidth()/2) groundRotator.setX(
         0);
      
      // Now this part is to wiggle bird up and down, we are going change 
      iterator based on time passed
      iterator += delta*400;
      
      // Then figure out the bird offset from it's original position based on 
      iterator which is based on time passed, and do it with sinus function
      float birdOffset = MathUtils.sinDeg(iterator)*5;
      
      // put bird on it's original pos + offset
      bird.setY(birdInitialPos + birdOffset); 
   }
   
}

 

BirdScript.java

 

package com.underwater.demo.overflappy;

import com.badlogic.gdx.math.MathUtils;
import com.badlogic.gdx.math.Vector2;
import com.uwsoft.editor.renderer.actor.CompositeItem;
import com.uwsoft.editor.renderer.actor.SpriteAnimation;
import com.uwsoft.editor.renderer.script.IScript;

/**
 * Bird Script
 * @author azakhary
 * This is brain of the bird, it's physics and everything
 */
public class BirdScript implements IScript {

   /*
    * reference to GameStage
    */
   private GameStage stage;
   
   // Bird composite item actor
   private CompositeItem bird;
   
   // Inside bird composite actor there is the bird sprite animation actor
   private SpriteAnimation birdAnimation;
   
   // used to wiggle the bird in the air using Sine function
   private float iterator = 0;
   
   // current vertical velocity of the bird
   private float currVerticalVelocity = 0;
   
   // boolean to know if gravity is enabled or not
   private boolean isGravityEnabled = false;
   
   // to avoid jumping to rotation bird will try to always rotate a bit towards 
   desired rotation
   private float desiredRotation;
   
   // is it alive?
   private boolean isAlive = true;
   
   
   public BirdScript(GameStage stage) {
      this.stage = stage;
   }
   
   @Override
   public void init(CompositeItem item) {
      bird = item;
      
      // find animation from the composite
      birdAnimation = bird.getSpriteAnimationById("birdAnimation");
      
      // set origin of the bird in it's center, so it will rotate normally
      bird.setOrigin(bird.getWidth()/2, bird.getHeight()/2);
      
      // set desired rotation to current rotation which is 0
      desiredRotation = bird.getRotation();
   }

   @Override
   public void act(float delta) {
      
      if(!isGravityEnabled && isAlive) {
         // Wiggling when no gravity only
         iterator += delta*400;
         float birdOffset = MathUtils.sinDeg(iterator)*5;
         birdAnimation.setY(birdOffset);
      }
      
      // aplying gravity every frame
      gravity(delta);
      
      // moving to new position based on current vertical velocity
      bird.setY(bird.getY() + delta*currVerticalVelocity);
      
      // manage bird rotation based on it's vertical speed
      manageRotation(delta);
      
   }
   
   /*
    * manage bird rotation based on it's vertical speed
    * this is a part of code that is not interesting boring and whatever..
    */
   private void manageRotation(float delta) {
      if(isGravityEnabled) {
         if(currVerticalVelocity > -200) {
            float rotation = currVerticalVelocity+200;
            desiredRotation = rotation/15f;
         }
         if(currVerticalVelocity <= -200) {
            float rotation = currVerticalVelocity+200;
            if(rotation < -400) rotation = -400;
            desiredRotation = rotation/4.4f;
         }
         
         if(desiredRotation != bird.getRotation()) {
            if(desiredRotation > bird.getRotation()) {
               bird.setRotation(bird.getRotation() + 900*delta);
               if(desiredRotation < bird.getRotation()) bird.setRotation(
                  desiredRotation);
            }
            if(desiredRotation < bird.getRotation()) {
               bird.setRotation(bird.getRotation() - 900*delta);
               if(desiredRotation > bird.getRotation()) bird.setRotation(
                  desiredRotation);
            }
         }
      }
   }
   
   public void enableGravity() {
      isGravityEnabled = true;
   }
   
   public void disableGravity() {
      isGravityEnabled = false;
   }
   
   public void jump() {
      // if bird is dead do not jump (I think I checked it somewhere already)
      if(!isAlive) return;
      
      // if bird is higher then screen then do not jump
      if(bird.getY() > stage.getHeight()) return;
      
      // if jumped get the custom variable jump_speed from bird actor and set it 
      as current vertical velocity
      currVerticalVelocity = bird.getCustomVariables().getFloatVariable(
                             "jump_speed");
   }
   
   /*
    * Apply gravity each frame (get's delta time since last frame)
    */
   private void gravity(float delta) {
      if(isGravityEnabled) {
         // change curernt velocity based on gravity (gravity changes velocity 
                                                      every second by gravity 
                                                      amount)
         currVerticalVelocity -= delta*bird.getCustomVariables().
                                 getFloatVariable("gravity");
      }
   }
   
   public CompositeItem getBird() {
      return bird;
   }
   
   // get's the bird center coordinates as vector 2 needed for collision 
   detection in GameScreenScript
   public Vector2 getBirdCenter() {
      Vector2 vec = new Vector2(bird.getX() + bird.getWidth()/2, bird.getY() + 
                    bird.getHeight()/2);
      return vec;
   }
   
   // Kills the bird, for reals
   public void die() {
      currVerticalVelocity = 0;  
      isAlive = false;
      desiredRotation = 0; 
      bird.setRotation(0);
      birdAnimation.pause();
   }

}

Programming Design


5. September 2014

 

 

Other than being a word my brain seems to think is spelled incorrectly, Particles are a common part of many games.  Fortunately Phaser has pretty good support for particles.  In this tutorial we are going to take a look at how they are used.

 

First, a quick introduction to particles.  A particle system is simply a mass of things, namely particles.  A particle is often ( as in this case ) a simple sprite.  The entire idea behind a particle system is to control a large number of particles using a single controller.  Particles are commonly used to create effects like fire and smoke, where each dozens, hundreds or thousands of smoke and flame particles are emitted ( pushed ) from the particle emitter.  As the emitter moves, so do the particles emitted from it.  This allows you to define over all behavior in the emitter, not each particle.  If that makes no sense, don’t worry, the examples below should clear it up.

 

Let’s take a look at a very basic emitter.  First we need a particle graphic.  In this case I am using the following graphic:

 

particle

 

It’s a simple transparent png image named particle.png.  Now the code:

 

/// <reference path="phaser.d.ts"/>

class SimpleGame {
    game: Phaser.Game;
    sound: Phaser.Sound;
    emitter: Phaser.Particles.Arcade.Emitter;

    constructor() {
        this.game = new Phaser.Game(640, 480, Phaser.AUTO, 'content', { create: 
                    this.create, preload: this.preload});
    }
    preload() {
        // Load the image we are going to use for our particle
        this.game.load.image("particle", "particle.png");
    }
    create() {
        // Now we are creating the particle emitter, centered to the world
        this.emitter = this.game.add.emitter(this.game.world.centerX, this.game.
                       world.centerY);
        // Make the particles for the emitter to emmit.  We use the key for the 
        particle graphic we loaded earlier
        // We want 500 particles total
        this.emitter.makeParticles('particle', 1, 500, false, false);
        // And BOOM, emit all 500 particles at once with a life span of 10 
        seconds.
        this.emitter.explode(10000, 500);
    }
}

window.onload = () => {
    var game = new SimpleGame();
};

 

Now when you run this code:

 

p1

 

500 particles using our png texture “explode” out of the emitter all at once.  The code is fairly heavily commented to explain what exactly is going on so I am going to move on to the next example.

 

Some ( most? ) of the time, you arent going to want all of your particles exploding all at once, except perhaps if you are modeling an explosion that is, instead you often want them to stream over time, perhaps from a moving source.  Also, you often want to use more than a single particle graphic for variety.  Finally, you often want those particles to physically interact with the world.  This example is going to do all of this.

 

This time we are going to use multiple (poorly edited by me) image files for our particles:

particleparticle2particle3

 

And now the code:

 

/// <reference path="phaser.d.ts"/>

class SimpleGame {
    game: Phaser.Game;
    sound: Phaser.Sound;
    emitter: Phaser.Particles.Arcade.Emitter;
    sprite: Phaser.Sprite;

    constructor() {
        this.game = new Phaser.Game(640, 480, Phaser.AUTO, 'content', {
            create: this.create, preload: this.preload,
            update: this.update
        });
    }
    preload() {
        // This time we have 3 different particle graphics to use
        this.game.load.image("particle", "particle.png");
        this.game.load.image("particle2", "particle2.png");
        this.game.load.image("particle3", "particle3.png");

        this.game.load.image("logo", "gfslogo.png");
    }
    update() {
        // This checks for and handles collisions between our sprite and 
        particles from the emitter
        this.game.physics.arcade.collide(this.sprite, this.emitter);
    }
    create() {
        var start = new Date().getTime();
        for (var i = 0; i < 1e7; i++) {
            if ((new Date().getTime() - start) > 10000) {
                break;
            }
        }
        this.emitter = this.game.add.emitter(0, 0);
        // As you can see, you can pass in an array of keys to particle graphics
        this.emitter.makeParticles(['particle', 'particle2', 'particle3'], 1, 
                                   500, false, false);
        // Instead of exploding, you can also release particles as a stream
        // This one lasts 10 seconds, releases 20 particles of a total of 500
        // Which of the 3 graphics will be randomly chosen by the emitter
        this.emitter.start(false, 10000, 20, 500, true);

        // This line of code illustrates that you can move a particle emitter.  
        In this case, left to right across
        // The top of the screen.  Ignore details tweening for now if it's new, 
        we will discuss later
        this.game.add.tween(this.emitter).to({ x: this.game.width }, 10000,null,
                            true,0,1,true).start();

        // Let's create a sprite in the center of the screen
        this.sprite = this.game.add.sprite((this.game.width / 2) - 100, (this.
                      game.height / 2) - 100, "logo");
        // We want it to be part of the physics of the world to give something 
        for particles to respond to
        // Note, we will cover physics in more detail later ( after tweening 
                                                              perhaps... ;) )
        this.game.physics.enable(this.sprite);
        this.sprite.body.immovable = true;
    }
}

window.onload = () => {
    var game = new SimpleGame();
};

 

And run it:

 

p2

 

As you can see, you can provide multiple particles, move the emitter and have it physically interact with the scene.  Don’t worry over much about tweening or physics, these are two subjects we will cover later in more detail.

 

In these two examples, we’ve looked at particles like you would use for special effects work, a very common situation.  That said, Particles can actually be used to control a large number of game entities that have common over all behavior, but randomized location, rotation, size or scale.  Take for example, a flight of animated birds.  You might want to add birds flying in the background of your game.  Let’s take a look at how to do this!

 

First I am using (a full sized version) of this sprite sheet taken from here.

robin-782x1024

 

It’s an animated sequence of a robin in flight.  It contains 22 frames, each 240x314 pixels in size.

 

Now let’s take a look at the code:

 

/// <reference path="phaser.d.ts"/>


// Create our own Particle class
class MyParticle extends Phaser.Particle {
    elapsedTime: number;
    currentFrame: number;
    static MAX_FRAME: number = 22;
    game: Phaser.Game;

    // In the constructor, randomly pick a starting frame of animation so all 
    the 
    // birds arent animated at the same rate
    constructor(game: Phaser.Game, x: number, y: number, key?: any, frame?: any) 
                {
        this.currentFrame = Math.floor(Math.random() * MyParticle.MAX_FRAME);
        this.elapsedTime = 0;
        this.game = game;

        // Now call Particle's constructor, passing in the spritesheet and frame 
        to use initially
        super(game, x, y, "ss", this.currentFrame);
    }

    update() {
        super.update();

        // Ever 100ms move to the next frame of animation
        this.elapsedTime += this.game.time.elapsed;
        if (this.elapsedTime >= 100) {
            this.currentFrame++;
            if (this.currentFrame > MyParticle.MAX_FRAME) this.currentFrame = 0;
            this.frame = this.currentFrame;
            this.elapsedTime = 0;
        }
    }
}

class SimpleGame {
    game: Phaser.Game;
    sound: Phaser.Sound;
    emitter: Phaser.Particles.Arcade.Emitter;

    constructor() {
        this.game = new Phaser.Game(640, 480, Phaser.AUTO, 'content', {
            create: this.create, preload:
            this.preload, render: this.render
        });
    }
    preload() {
        // Load the spritesheet containing the frames of animation of our bird
        // The cells of animation are 240x314 and there are 22 of them
        this.game.load.spritesheet("ss", "robin.png", 240, 314, 22);
    }
    render() {
    }
    create() {
        // Now we are creating the particle emitter, centered to the world
        this.emitter = this.game.add.emitter(this.game.world.centerX, this.game.
                       world.centerY);

        this.emitter.particleClass = MyParticle;
        this.emitter.makeParticles();
        
        // In this case, we dont want gravity affecting the birds and we dont 
        want them to rotate
        this.emitter.gravity = 0;
        this.emitter.minRotation = 0;
        this.emitter.maxRotation = 0;

        // Now start emitting particles.  Total life of 1000 seconds, create one 
        per 500ms ( 2/sec )
        // and create a total of 100 birds.
        this.emitter.start(false, 100000, 500, 100, true);
    }
}

window.onload = () => {
    var game = new SimpleGame();
};

 

And when run:

 

p3

 

The terrible graphics are a side effect of being converted to an animated GIF that would take forever to download!

 

It just dawned on me that I haven’t actually covered Spritesheets yet… oops.  Hey, this is how you use a spritesheet! :)  Don’t worry if you struggle with the spritesheet portions, we will cover that later as well.  The important part here is the Particle itself.  In this example we extend the class Particle to create our own Particle class.  This class then handles updating itself resulting in the animation of the bird.  Obviously you could put a great deal more logic in there, although be sure to keep things pretty light computationally, especially if you intend to create a number of them.

 

This example actually illustrates a couple of really nice features of TypeScript, but maps nicely to Phaser’s JavaScript.  The first in the concept of a constructor.  This is code that is called as the object is created.  The next more important concept is class and extend.  In this case we are extending an existing JavaScript class, Particle.  A quick look behind the curtains now.

 

In TypeScript we write:

 

class MyParticle extends Phaser.Particle

 

This results in the JavaScript

 

var __extends = this.__extends || function (d, b) {
    for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
    function __() { this.constructor = d; }
    __.prototype = b.prototype;
    d.prototype = new __();
};
// Create our own Particle class
var MyParticle = (function (_super) {
    __extends(MyParticle, _super);

 

Pretty cool stuff, and certainly easier to read and maintain.

 

A Small Bug

 

While writing this I ran into a small bug I figured I should make you aware of ( and one of the downsides of working with TypeScript ).  In the code sample we had the following line:

 

this.emitter.particleClass = MyParticle;

 

This line is specifying the type of class to use for a Particle, no an instance of the class.  Unfortunately the Phaser.d.ts file is incorrect in it’s definition.  It instead expects particleClass to receive a Phaser.Particle instance.  This is wrong ( and took some time to route out ).  In the definition, if not fixed by the time you read this, make the following edit to Emitter:

 

particleSendToBack: boolean;
// MJF Fix particleClass: Phaser.Sprite;
particleClass: any;

 

Hopefully that will be fixed by the time you read this.

 

Programming


27. August 2014

 

Today we are going to look at implementing physics in LibGDX.  This technically isn’t part of LibGDX itself, but instead is implemented as an extension.  The physics engine used in LibGDX is the popular Box2D physics system a library that has been ported to basically every single platform and language ever invented, or so it seems. We are going to cover how to implement Box2D physics in your 2D LibGDX game.  This is a complex subject so will require multiple parts.

 

If you’ve never used a Physics Engine before, we should start with a basic overview of what they do and how they work.  Essentially a physics engine takes scene information that you provide, then calculates “realistic” movement using physics calculations.  It goes something like this:

  • you describe all of the physics entities in your world to the physics engine, including bounding volumes, mass, velocity, etc
  • you tell the engine to update, either per frame or on some other interval
  • the physics engine calculates how the world has changed, what’s collided with what, how much gravity effects each item, current speed and position, etc
  • you take the results of the physics simulation and update your world accordingly.

 

Don’t worry, we will look at exactly how in a moment.

 

First we need to talk for a moment about creating your project.  Since Box2D is now implemented as an extension ( an optional LibGDX component ), you need to add it either manually or when you create your initial project.  Adding a library to an existing project is IDE dependent, so I am instead going to look at adding it during project creation… and totally not just because it’s really easy that way.

 

When you create your LibGDX project using the Project Generator, you simply specify which extensions you wish to include and Gradle does the rest.  In this case you simply check the box next to Box2d when generating your project like normal:

 

image

 

… and you are done.  You may be asking, hey what about Box2dlights?  Nope, you don’t currently need that one.  Box2dlights is a project for simulating lighting and shadows based off the Box2d physics engine.  You may notice in that list another entity named Bullet.  Bullet is another physic engine, although more commonly geared towards 3D games, possibly more on that at a later date.  Just be aware if you are working in 3D, Box2d isn’t of much use to you, but there are alternatives.

 

Ok, now that we have a properly configured project, let’s take a look at a very basic physics simulation.  We are simply going to take the default LibGDX graphic and apply gravity to it, about the simplest simulation you can make that actually does something.  Code time!

 

package com.gamefromscratch;

import com.badlogic.gdx.ApplicationAdapter;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.g2d.Sprite;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.physics.box2d.*;

public class Physics1 extends ApplicationAdapter {
    SpriteBatch batch;
    Sprite sprite;
    Texture img;
    World world;
    Body body;

    @Override
    public void create() {

        batch = new SpriteBatch();
        // We will use the default LibGdx logo for this example, but we need a 
        sprite since it's going to move
        img = new Texture("badlogic.jpg");
        sprite = new Sprite(img);

        // Center the sprite in the top/middle of the screen
        sprite.setPosition(Gdx.graphics.getWidth() / 2 - sprite.getWidth() / 2,
                Gdx.graphics.getHeight() / 2);

        // Create a physics world, the heart of the simulation.  The Vector 
        passed in is gravity
        world = new World(new Vector2(0, -98f), true);

        // Now create a BodyDefinition.  This defines the physics objects type 
        and position in the simulation
        BodyDef bodyDef = new BodyDef();
        bodyDef.type = BodyDef.BodyType.DynamicBody;
        // We are going to use 1 to 1 dimensions.  Meaning 1 in physics engine 
        is 1 pixel
        // Set our body to the same position as our sprite
        bodyDef.position.set(sprite.getX(), sprite.getY());

        // Create a body in the world using our definition
        body = world.createBody(bodyDef);

        // Now define the dimensions of the physics shape
        PolygonShape shape = new PolygonShape();
        // We are a box, so this makes sense, no?
        // Basically set the physics polygon to a box with the same dimensions 
        as our sprite
        shape.setAsBox(sprite.getWidth()/2, sprite.getHeight()/2);

        // FixtureDef is a confusing expression for physical properties
        // Basically this is where you, in addition to defining the shape of the 
        body
        // you also define it's properties like density, restitution and others 
        we will see shortly
        // If you are wondering, density and area are used to calculate over all 
        mass
        FixtureDef fixtureDef = new FixtureDef();
        fixtureDef.shape = shape;
        fixtureDef.density = 1f;

        Fixture fixture = body.createFixture(fixtureDef);

        // Shape is the only disposable of the lot, so get rid of it
        shape.dispose();
    }

    @Override
    public void render() {

        // Advance the world, by the amount of time that has elapsed since the 
        last frame
        // Generally in a real game, dont do this in the render loop, as you are 
        tying the physics
        // update rate to the frame rate, and vice versa
        world.step(Gdx.graphics.getDeltaTime(), 6, 2);

        // Now update the spritee position accordingly to it's now updated 
        Physics body
        sprite.setPosition(body.getPosition().x, body.getPosition().y);

        // You know the rest...
        Gdx.gl.glClearColor(1, 1, 1, 1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
        batch.begin();
        batch.draw(sprite, sprite.getX(), sprite.getY());
        batch.end();
    }

    @Override
    public void dispose() {
        // Hey, I actually did some clean up in a code sample!
        img.dispose();
        world.dispose();
    }
}

 

The program running:

 

test

 

What's  going on here is mostly defined in the comments, but I will give a simpler overview in English.  Basically when using a Physics Engine, you create a physical representation for each corresponding object in your game.  In this case we created a physics object ( Body ) that went along with our sprite.  It’s important to realize, there is no actual relationship between these two objects.  There are a couple of components that go into a physics body, BodyDef which defines what type of body it is ( more on this later, for now realize DynamicBody means a body that is updated and capable of movement ) and FixtureDef, which defines the shape and physical properties of the Body.  Of course, there is also the World, which is the actual physics simulation.

 

So, basically we created a Body which is the physical representation of our Sprite in the physics simulation.  Then in render() we call the incredibly important step() method.  Step is what advances the physics simulation… basically think of it as the play button.  The physics engine then calculations all the various mathematics that have changes since the last call to step.  The first value we pass in is the amount of time that has elapsed since the last update.  The next two values control the amount of accuracy in contact/joint calculations for velocity and position. Basically the higher the values the more accurate your physics simulation will be, but the more CPU intensive as well.  Why 6 and 2?  ‘cause that’s what the LibGDX site recommend and that works for me.  At the end of the day these are values you can tweak to your individual game.  The one other critical take away here is we update the sprites position to match the newly updated body’s position.  Once again, in this example, there is no actual link between a physics body and a sprite, so you have to do it yourself.

 

There you go, the worlds simplest physics simulation.  There are a few quick topics to discuss before we move on.  First, units.

 

This is an important and sometimes tricky concept to get your head around with physics systems.  What does 1 mean?  One what?  The answer is, whatever the hell you want it to be, just be consistent about it!  In this particular case I used pixels.  Therefore 1 unit in the physics engine represents 1 pixel on the screen.  So when I said gravity is (0,-98) that means gravity is applied at a rate of –98 pixels along the y axis per second.  Just as commonly, 1 in the physics engine could be meters, feet, kilometer, etc… then you use a custom ratio for translating to and from screen coordinates.  Most physics systems, Box2d included, really don’t like you mixing your scales however.  For example, if you have a universe simulation where 1 == 100 miles, then you want to calculate the movement of an Ant at 0.0000001 x 100miles per hour, you will break the simulation, hard.  Find a scale that works well with the majority of your game and stick with it.  Extremely large and extremely small values within that simulation will cause problems.

 

Finally, a bit of a warning about how I implemented this demo and hopefully something I will cover properly at a later date.  In this case I updated the physics system in the render loop.  This is a possibility but generally wasteful.  It’s fairly common to run your physics simulation at a fixed rate ( 30hz and 60hz being two of the most common, but lower is also a possibility if processing restrained ) and your render loop as fast as possible.

 

In the next part we will give our object something to collide with, stay tuned.

Programming


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