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9. September 2016

 

Never in the history of game development have indie developers, or developers in general, had access to such a massive array of resources.  What is perhaps most impressive is that so many of these tools are available at no cost.  That is exactly what this guide is going to look at, and end to end look at freely available tools for all facets of game development. 

There is also a video version of this guide available here.

This guide is not meant to be comprehensive, I don’t want to flood the reader with too much choice.  I do however want to make sure I capture the “greatest hits”, so If I miss a package that you believe should have been included, please let me know!

 

The Definition of Free

First off, this point needs to be addressed right up front.  To use a popular open source expression, I am talking free as in beer, not free as in freedom.  This means that non-open source tools are going to be included, although when source is available I well mention.  The primary criteria is that the developer can get started and develop using the tool completely free.  There might however be a cost after a certain revenue threshold is met (I find this to be an exceedingly fair business model personally) or there might be multiple tiers available, so long as it includes a free tier that enables you to ship and sell your title, it will be eligible for this guide.  It will also include software and tools that have a premium version available, just know that I am referring to the free tier in this guide.

 


Art

In this section we will look at the essential tools for creating game development art, both 2D and 3D.

 

2D

There are a wide variety of 2D imaging applications available, some specialized for developing and animating 2D game sprites, while others are more general purpose image manipulation applications or painter focused.

 

Paint.Net – Windows

An excellent, easy to use general purpose Painting application with hundreds of plugins available, layer support and more.  Frankly this is my goto application for simple image manipulation tasks.  Featured Paint.NET in the GameDev Toolbox series if you want to learn more.  Sadly it is Windows only software.

 

GIMP – Various – Open Source

Pretty much the closest thing to an open source alternative to Photoshop.  It’s a powerful application with an unwieldy UI.  Thankfully they have been focusing heavily on making UI improvements.

 

Inkscape – Various – Open Source

Inkscape is different from other applications on this list as it’s Vector based (instead of bitmap/raster based).  It takes an approach similar to Adobe Illustrator or Flash and is very useful for creating resolution independent graphics.

 

Krita – Linux/Mac/Windows – Open Source

Krita is an open source application that is focused on digital painting, similar to commercial products like Corel Painter.  In recent releases however it has been extended to add animation and text support, making it more and more useful for game development.

 

ASESprite – Windows/Mac/Ubuntu

This is app is dedicated to creating and animating 8/16bit style sprites.  Supporting painting, layers, onion skinning, fixed color pallet, sprite sheet generation and more.

 

GratfX2 – Various – Open Source

Once upon a time there was a program called Deluxe Paint and it was responsible for art creation for 99% of games developed.  GrafX2 is an open source implementation of that application.

 

Piskel – Mac/Linux/Windows/Web – Open Source

Piskel is another pixel art oriented image editor, although this one is somewhat unique in being usable in the browser, with offline versions available for download.  Supports layers, palletes, animation frames and more.

 

JPixel – Various

Not technically free, it’s a name your own price application, however that price can be $0.  It’s a pixel art application with support for animations, tilesets, color palettes and more.

 

GraphicsGale – Windows

The free version of this application is mostly just limited in what file formats it supports for export.  Sadly it is Windows only.  Offers pretty much every feature you would expect from a pixel graphics oriented application.

 

ShoeBox – Adobe Air

ShoeBox is an image/sprite/texture manipulation tool.  Useful for creating textures from existing images, extracting an animation into a sequence of sprites, creating 9patch images and more.  This is a utility and not a graphics creation package like many in this list.  It requires the Adobe Air runtime to run.

 

TexturePacker – Mac/Windows

TexturePacker by Code and Web is a utility designed to create sprite sheets.  Like ShoeBox above it is not an image creation or modification application.  There is a free version but limits some advanced features.

 

DragonBones – Windows/Mac

Unique in this list, DragonBones is a 2D animation system that enables you to use bone based IK animation to control and animate 2D images.  It’s similar in function to Creature, Spriter and Spine but is completely free.  It comes with runtimes for playing your animations in various game engines.

 

OpenToonz – Windows/Mac

An open source implementation of Toonz, originally developed by Studio Ghibli and used to help make Princess Mononoke, is completely free to use.  Aimed primarily at film animations, Toonz has been used to create animation for games in the past.  Not an easy tool to master.

 

TileCraft – Windows/Mac/Linux – Open Source

TileCraft is a unique little tool for creating 2D sprites using a 3D workflow.  Essentially you add and subtract solid 3D shapes to create more complex 2D images.  It’s an interesting approach and is open source, but sadly hasn’t been updated in over a year.

 

3D

 

Blender – Most Platforms – Open Source

Blender is certainly the biggest 3D package available for free, it’s also open source and remarkably full featured.  Model, sculpt, animate, physics simulation, render and composite all using a single program.  There is a ton of power here, but also a huge learning curve.  Thankfully, I’ve got you covered with a pair of tutorial series.

 

Daz Studio – Windows/Mac

Daz Studio is a 3D package, focused heavily on characters.  It’s incredibly easy to use, is available for free, while they make money selling 3D models, outfits, etc.  It is similar in scope and functionality to another application called Poser, which is not available in a free form.  A warning however, they will spam the email address you register with.

 

Dilay – Windows/Linux – Open Source

Dilay is a free open source 3D sculpting tool in the same vein as Mudbox, Sculptris and ZBrush.  I featured Dilay in this video if you wish to learn more.

 

MagickaVoxel – Windows/Mac

MagickaVoxel is a free to use Voxel editor.  Voxels are an alternative to traditional polygon approach to models, essentially composing objects out of blocks in 3D space. Minecraft is the most famous Voxel based game, but there are plenty of other examples preceding Minecraft.

 

Mixamo/Mixamo Fuse – Windows

Mixamo is a gigantic animation data base, and set of tools for applying animations to 3D models.  Mixamo FUSE is a 3D character creator, using a video game like interface for making 3D character models.  It was purchased by Adobe and currently is available for completely free.  I reviewed Fuse before the Adobe acquisition if you want an idea of what you are getting.  This is perhaps the simplest way to create 3D character models and is certainly the easiest way to animate them.

 

PolyBrush – Windows

PolyBrush is a one of a kind 3D sketching app, enabling you to create complex organic 3D shapes using a sketching workflow.  There is a free version available with some limitations ( single layer, max 8 undo levels, cannot save brushes ) but it is perfectly functional.  I featured Polybrush in this video should you wish to learn more.

 

Sculptris – Windows/Mac

A free 3D sculpting tool from Pixologic, the makers of ZBrush.  It’s not actively developed anymore, but is a great introduction to sculpting and the results can be exported for use in other software such as Blender.  For more details you can watch our Scultpris feature in the GameDev Toolbox series.

 

Wings 3D – Most Platforms – Open Source

Wings is an excellent 3D modeling application built around the Winged Edge polygon.  It enables fast and fairly easy 3D model creation.  Development however appears to have stopped sadly.  In recent years the 3d modeling tools in Blender have also improved greatly, making Wings less and less valuable.

 


Audio

By far my weakest area of knowledge, the following are applications freely available and used to create and edit audio from sound effects to background music.

 

Audacity – Windows/Mac/Linux – Open Source

Audacity is the swiss army knife for recording, translating and modifying audio files.  Simply put you should stop everything and download this tool if you haven’t done so already.  Audacity was featured in the GameDev Toolbox series if you want more information.

 

SunVox – Various

SunVox is a class of program called a ModTracker and can be used to create music.  The interface is simply daunting, but the effects can be pretty amazing.  Runs on just about every platform created by man and possibly aliens.  Was featured in the GameDev Toolbox series as well.

 

ChipTone – Web

ChipTone is like a streamlined version of SunVox that runs in your browser.  Comes with several game focused samples and the ability to record your own.

 

Bfxr.net – Web

A web based sound fx generator.  Very easy to use, start with several default sounds ( explosion, laser, etc. ) then modify the generator to create exactly the effect you need, then download locally.  Dead simple.

 

FMod – Windows/Mac

FMod is perhaps the most used game middleware for AAA and A game titles.  While it’s commercial software, it’s free to use if make less than $100K USD a year. They also offer FMod.io that gives access to a gigantic library of sound effects for 99cents each.  There is a first look video of FMOD.io available here.

 

Podium Free – Windows

Podium is a surprisingly full featured free version of Podium.  Podium is a digital audio workstation (DAW) that enables you to create, record and edit audio and MIDI as well as hosting VST instruments and effect plugins.

 


 

Code

 

This is where the various programming languages and development tools are listed.  Just a few years ago many of these products cost many hundred or thousands of dollars.  These days most programming tools are made available for basically free.  This features only the languages and tools most commonly used in game development.  There are dozens of programming languages and literally hundreds of tools, so a line in the sand must be made.

 

Please note, you often don’t require a programming language at all, at least not a stand alone one.  It’s increasingly common for many game engines to include the entire tool-chain for you, basically hiding this layer from you.  Additionally, some may find using an IDE as way too heavy.  Don’t worry however, you can also work entirely from the command line or terminal and use a lighter weight code editor should you prefer.

 

Languages and IDEs

 

Visual Studio Community – Windows

Visual Studio Community is perhaps the most used IDE (Integrated Developer Environment) in the world of both Windows development and game development in general.  It includes several programming language, but C++, JavaScript and C# are the most commonly used for game development (VB.Net, F# and TypeScript are also supported).  It also contains editors, debuggers, source control and much more.  In fact it contains so much more it’s actually rather bloated at this point, resulting in an install size north of 10GB.  Visual Studio Community is a revenue/team size limited version of the full Visual Studio package.  It’s essentially the same product and for individuals there is no limitation, for organizations there is a team size limit of 5 developers and $1M USD in revenue.  For Enterprise organizations, usage is not permitted.  You can read the full license details here.

One recent change with Visual Studio is Microsoft recently acquired Xamarin, and made it’s suite of products available free as part of Visual Studio Community.  This now gives you the ability to target iOS and Android using Visual Studio and C#. 

 

XCode – MacOS

XCode is the Apple equivalent of Visual Studio and is a requirement to sign and package iOS applications.  It can be used to develop for the various Apple platforms ( OS X, iOS, AppleTV, etc. ) with the primarily languages being Objective C and now Swift.  C++ is also fully supported, but is treated like a bit of a red headed stepchild for some unfathomable reason.  Like Visual Studio it contains a full set of development tools including code editors, an integrated debugger, forms designers and more.  XCode used to require a developer subscription with Apple but this requirement and fee has now been removed.  On a personal note, I’d rather use my forehead as a hammer than use XCode, but that’s just me.

 

GNU Tool Chain – Various – Open Source

GCC, or the GNU compiler collection, is a set of open source developer tools including support for just about every single language you’ve ever dreamed of using.  If you are developing on Linux, chances are you already have much of the GNU toolchain installed.  One caveat of the GNU suite is the GPL or Gnu Public License.  This open source license greatly restricts what you can do with the software, basically requiring you to make all changes and modifications to the code open and available.  Don’t worry, this restriction only applies to changes to tools themselves, not code you compile using them.  As mentioned earlier, GCC is generally included with any Linux distribution.  There are also ports to various platforms such as MingW for Windows or MacPorts on Windows.  Keep in mind GCC is NOT an ide, it’s the underlying compiler/linker/debugger.  Generally some form of editor is required as well.

 

LLVM(Clang) – Various – Open Source

LLVM, which isn’t actually an acronym no matter what other people tell you, is a suite of tools very similar to GCC.  It is instead released under the much more liberal BSD license and is the underyling technology behind a lot of commercial tools as a result, including XCode mentioned earlier, as well as closed development kits, such as the PlayStation 4.  An LLVM implementation is available as part of the MingW port, while it can also be used directly inside Visual Studio.  Like GCC, this is a lower level suite of tools and generally still requires an editor for code creation.

 

Qt Creator – Windows/Mac/Linux

Qt Creator is a full cross platform IDE primarily for C++ programming.  It’s has several tools designed to work with the Qt cross platform UI toolkit, but can be used as a standalone C++ development environment.  It includes a code editor, debugger, project management tools, UI designers, etc just like VS and XCode.

 

JetBrain’s Suite Of Products – Most Platforms

Instead of listing each product individually, it’s probably easier to mention the entire suite.  Most of the IDEs made by JetBrain offer a free version that is generally enough for most developers needs.  Perhaps their most known product is IntelliJ IDEA a Java IDE that has plugin support for dozens of programming languages.  They also have C#, C++, HTML/JavaScript, Python, etc. IDEs available as well.  

 

Eclipse – Most Platforms

Primarily a Java IDE, plugins have extended it’s functionality to support several other languages.  Full suite of tools and used to be the preferred development path for Android development (it is no longer).  Eclipse has everything and the kitchen sink.  Personally I’d rather code using morse code then use Eclipse again, but I figured I’d mention it for completeness.

 

Netbeans – Most Platforms

Oracle’s Java IDE, but can add support for other languages via plugins.  Again full featured, but certainly enterprise focused.  I’d prefer it to Eclipse, but then, I’d prefer just about anything to Eclipse.

 

Other Languages of Note:

 

Special Note for Android Developers

Android is a bit of a special case for development.  While based on Java, it’s not technically using Java (it’s a long story and got Google sued).  So long and short of it, there are special tools for Android development, specifically the Android SDK(Java) and the Android NDK(C++).  Google also make an IDE called Android Studio available, a port of the IntelliJ IDE, specifically for IDE development.

 

Editors

The following are code oriented text editors.  Don’t want the heavy install of a full IDE, are using a game engine that doesn’t include it’s own editor (or it’s built in editor sucks?), then you will probably want one of these.  Each of the following generally offer most of the following: multiple language support, plugin extensibility, syntax highlighting, refactoring tools and more.  Choosing the right editor is a deeply personal experience... Im not going to start any wars here... just list the options available... you pick your favorite.

And just so I don’t fend the old timers...

Just be aware of the learning curve, you will need to memorize about a hundred character combinations to become proficient with either of these editors.  That said, once you’ve got them down they can be exceedingly efficient.  It’s worth noting however the VI and Emacs keyboard bindings are often available in other editors.  A quick note here, Visual Studio Code and Visual Studio Community have NOTHING in common.  Code is a light weight cross platform editor, not a Windows only IDE.

 


 

Tools and Misc

Didn’t fit somewhere else but is available for free?  It goes here.

 

Tiled – Windows/Linux/Mac – Open Source

The preeminent free 2D map editing software package.  The map files Tiled generates are supported by just about every game engine available.  We have a full Tiled tutorial series available if you wish to learn more.

 

FreeMind – Various – Open Source

Freemind is an open source mind mapping package.  If you’ve never used one before, this is a great way to get ideas from your head to your computer.  There are actually a massive number of mind mapping packages available, FreeMind just happens to be the one I’m most familiar with.

 

ShaderToy – Web

GPU Shaders are becoming more and more critical to the world of game development and ShaderToy is perhaps the primary place to share and download shaders on the web.  You can also modify the shader source and see the results in real time.  Almost 12,000 shaders currently exist in the collection and growing daily.

 

FreeSound.org – Web

A huge collection of free audio files.

 

OpenGameArt.org – Web

A massive collection of free game graphics.

 

VST4Free.org – Web

A resource for VST instruments and effects.  VST stands for Virtual Studio Technology an enables you to encode samples of actual instruments, special sound effects etc. and use them in VST compatible instruments and software such as Podium mentioned earlier.

 


Game Engines

This is a section that could fill a few hundred pages and only just get started.  The reality is, almost every single game engine is available in a free form with differing business models.  Some such as Unreal Engine take a percentage of your revenue after certain thresholds are exceeded.  Others like Unity offer a free tier which has limitations, such as a maximum annual revenue, and require a subscription if you exceed those amounts.  There are also game engines like Godot, Urho, Atomic and Panda that are completely free and open source.  Then there are all the various frameworks such as SFML, LibGDX, SDL, Love, etc. many of which are open source and freely available.

 

This topic is well beyond this guide’s ability to cover.  Thankfully I’ve slowly been reviewing many of these engines and frameworks as part of the Closer Look series.

 


The Video

 

Design Art General Programming


13. May 2016

 

One of the challenges with prototyping games is finding assets to work with.  Simple boxes are fine, but if you are working on a game with animations this proves a bit more challenging.  Therefore I created a simple sequence of spritesheets you can use in your game.   The package includes an idle, walk cycle, jump up and forward, death and duck animations.  This animation shows all of the various frames of animation.  The character was created using Fuse then animated using Mixamo and finally exported to sprite sheets using TexturePacker.

gifanimation

 

There are several different options here. 

 

Raw Sprites

( Download Link 18MB )

These are all of the raw sprites as individual files, each sprite is 512x512 pixels in size.

 

Phaser Sprite Sheets

( Download Link 13MB )

This is a set of sprite atlases and a JSON Array format for consuming in the Phaser game engine.  (See below for code)

 

Generic Sprite Sheets

( Download Link 14MB )

This is simply all of the frames of animation across several separate images, usable in any game engine.

 

License

CC0 icon These files are released under the Creative Commons CC0 license.  Basically do what you will, how you will, when you will, with whomever you will.  I on the other hand assume no responsibility for anything that may happen as a result.

 

Using In Code

The following is a example of using the generated spritesheet in Phaser, a popular HTML5 game library.  The entire project is available here as a zip.  If you are interested in learning more about Phaser I have a complete tutorial series available here.

function Game() {}

var character;

Game.prototype.preload = function () {
    this.game.load.atlas('walkSS','assets/walk.png','assets/walk.json', Phaser.Loader.TEXTURE_ATLAS_JSON_ARRAY);
    this.game.load.atlas('dieSS','assets/die.png','assets/die.json', Phaser.Loader.TEXTURE_ATLAS_JSON_ARRAY);
    this.game.load.atlas('idleSS','assets/idle.png','assets/idle.json', Phaser.Loader.TEXTURE_ATLAS_JSON_ARRAY);
    this.game.load.atlas('jumpForwardSS','assets/jumpForward.png','assets/jumpForward.json', Phaser.Loader.TEXTURE_ATLAS_JSON_ARRAY);
    this.game.load.atlas('jumpUpSS','assets/jumpUp.png','assets/jumpUp.json', Phaser.Loader.TEXTURE_ATLAS_JSON_ARRAY);
    this.game.load.atlas('rollSS','assets/roll.png','assets/roll.json', Phaser.Loader.TEXTURE_ATLAS_JSON_ARRAY);
};

Game.prototype.create = function () {
  this.input.onDown.add(this.onInputDown, this);
    character = this.game.add.sprite(0,0,'idleSS',0);
    character.animations.add("idle");
    character.animations.play("idle",30,true);
};

Game.prototype.update = function () {};

Game.prototype.onInputDown = function () {
};

module.exports = Game;

 

All of the binaries used to generate this project, including the FBX animations, a fully configured Blend file, etc. are available for download by Patreon backers.  Simply log in to your Patreon account for the download link and password.

Art


5. May 2016

 

Introduction

Welcome to the first part of a multipart tutorial series on creating games using the Haxe programming language with the Heaps graphics engine.  Heaps is under development by Nicolas Cannasse, the guy that created the Haxe language in the first place.  In his own words:

Heaps is a cross platform graphics engine designed for high performance games. It's designed to leverage modern GPUs that are commonly available on both desktop and mobile devices. The framework currently supports HTML5 WebGL, Flash Stage3D, native Mobile (iOS and Android) and Desktop with OpenGL. 

Heaps is a very cool library, but not an incredibly well documented one.  So that’s where this tutorial series comes in.  We are going to look at creating 2D then 3D graphics using the Heaps engine.  For this series I will be doing both text and video versions of each tutorial.  The video version of this tutorial is available here.

 

Setting Up Your Haxe Development Environment

This tutorial is going to assume you are using Windows, if you are on another operating system, the steps are going to vary slightly.

First head to Haxe.org/download and download the appropriate Haxe installer for the most reason version.

image 

In my case I am going with the Windows Installer.  Run the executable and say yes to any security messages you receive.  You want to install everything like so:

image

 

Install where ever you like:

image

 

Verify your install worked correctly.  Fire up a command prompt and type haxelib version:

image

 

That was easy, eh?  Next you will probably want an IDE or Editor.  Personally I am using Haxe Develop, a special port of Flash Develop.  This is a Windows only IDE though.  Another option is Visual Studio Code with the Haxe language extensions.

 

Finally we need to install the Heaps library.  It’s not registered with Haxelib yet, so we currently have to install it from Github.  Run the command:

 

haxelib git heaps https://github.com/ncannasse/heaps.git

image

 

And done.

 

Creating a Hello World application

Now let’s create our first application to make sure everything is up and running correctly.  A simple hello world app.

Assuming you are using HaxeDevelop, go ahead and create a new project via Project->New Project

image

 

I created a JavaScript project like:

image

 

Inside our project folder, we need to create a folder for our resources.  I simply created a directory called res.  Simply right click your project in the Project panel and select Add->New Folder...

image

 

Next we need a TTF file, I personally used this font.  Simply download that zip and copy the ttf file into the newly created res directory.  You can open an Explorer window to that directory by right clicking it and selecting Explore.  I personally renamed it to not be all caps, it should work either way though.  If you are using HaxeDevelop, your project should look something like this:

image

 

We have two final bits of configuration.  First we need to text HaxeDevelop that we use the Heaps library, and that the resource folder is named Res.  Right click your project and select Properties

image

 

Next select the Compiler Options tab.  First add an entry to Compiler options with the value –D resourcePath=”res”.  Then add a value to Libraries of heaps.  That’s it, click Apply then Ok.

image

 

Finally some code!  First we need a WebGL canvas for our application to run in.  Simply open up index.html located in the Bin folder and add a canvas.  Your code should look something like:

<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="utf-8"/>
	<title>JSTest</title>
	<meta name="description" content="" />
</head>
<body>
	<canvas id="webgl" style="width:100%;height:100%"></canvas>
	<script src="JSTest.js"></script>
</body>
</html>

 

Now we need to edit our main Haxe code.  By default it will be called Main.hx and it’s the entry point (and entirety) of our program.  Enter the following code:

import h2d.Text;
import hxd.Res;
import hxd.res.Font;
import js.Lib;

class Main extends hxd.App {
        var text : Text;

		// Called on creation
        override function init() {
			// Initialize all loaders for embeded resources
			Res.initEmbed();
			// Create an instance of wireframe.tff located in our res folder, then create a font2d of 128pt size
			var font = Res.wireframe.build(128);
			// Create a new text object using the newly created font, parented to the 2d scene
            text = new Text(font, s2d);
			// Assign the text
			text.text = "Hello World";
			// Make it read, using hex code ( RR GG BB, each two hex characters represent an RGB value from 0 - 255 )
			text.textColor = 0xFF0000;
        }

		// Called each frame
        override function update(dt:Float) {
			// simply scale our text object up until it's 3x normal size, repeat forever
			var scaleAmount = 0.01;
			if (text.scaleX < 3.0) text.setScale(text.scaleX + scaleAmount);
			else text.setScale(1);
			
        }

        static function main() {
            new Main();
        }
    }

Now go ahead and run your code by either hitting F5 or click this button image

You should see:

GIF

 

Congratulations, your first Haxe programming using the Heaps library.  Next up, we will jump into 2D graphics with Heaps.

 

Video

Programming


29. April 2016

 

TexturePacker is a handy tool I’ve featured several times here on GameFromScratch as well as a video feature as part of the gamedev toolbox series.  It’s one of those handy Swiss army style tools that enables you to pack multiple images into one or more sprite sheets.  Texture Packer 4.2 brings a number of new features to the table:

  • a simplified user interface is available now for new users
  • improved help
  • indexed PNG (PNG-8) (more) available
  • improved sprite sheet animation previewer

Sprite sheet animation previewer

  • support for ETC2, PVRTCII, DXT1/5 formats
  • user interface cleanup
  • several fixes
    • all data formats now use UTF-8
    • EaselJS/CreateJS animation frames now written correctly
    • now case sensitive aware on MacOS
    • better Cocos2d-x support

GameDev News


25. April 2016

 

One of the major advantages to working in 3D is once you have your character modeled and rigged, creating new animations is simply a matter of defining a series of poses on a timeline.  Animations are generally defined by moving a series of bones controlling your mesh, which in turn are powered by a system called inverse kinematics.  IK is basically a fancy way of saying “move an end bone and the computer will calculate how all the other bones in the chain will respond” enabling you to animate by positioning the foot forimage example and the ankle, knee and hip will rotate appropriately.  It’s a pretty powerful way to perform animation and every single major 3D application implements IK (and FK – forward kinematics).

 

In the land of 2D art, the process is often quite different.  Generally the approach here is to generate a sprite sheet, which is a sequence of slightly altered versions of the same character, which played in sequence results in an animation.  If you ever done a flipbook animation at the top corner of any of your textbooks, you already have the process of traditional 2D animation down.  There are other techniques such as onion skinning and rotoscoping to aid in the animation process, but it still remains time intensive.  If only there was some way to take the 3D worlds bone based animations and apply them to generating 2D art?  Well, there is... Spine.

 

Today we are going to look inside Spine, look at the art generation process, how to make sprite graphics that are animation ready, define an animation, then perhaps most importantly, play that animation back in our game engine of choice.  Since Spine itself is built over top of the LibGDX library (by one of the frameworks founders to boot), therefore I suppose a LibGDX example makes the most sense.  If you are bored, the story of how Spine came to be is an interesting read.

 

Full disclosure, I requested a review license in order to get hands on time with Spine.  Additionally some of the assets I am using in this demonstration are part of asset packs available for purchase and aren’t my creation.  Spine is commercial software, ranging in price from $70 for the essentials version, $300 for professional and $2200 for enterprise (which is tied to your companies revenue).  There is a free trial available and capable of doing everything we are about to do below except export and run in code.  Without further ado, let’s jump in.  As is often the case on GameFromScratch, if you prefer a video version one is available here as well as embedded below.

 

Meet Spine

Here is the main Spine interface:

image

 

It’s actually an exercise in simplicity which I appreciate.  It also supports UI scaling, so works well on high DPI displays, something far too many applications suck at, so I also appreciate that.  The left hand viewport is where the magic happens, this is where you compose your characters and animations, while on the right hand side you’ve got your project hierarchy a scene graph of sorts.  The primary UI is across the bottom of the screen.  You can easily pan and zoom around the display using a combination or RMB and Ctrl + RMB.  There is some additional complexity hidden away behind this menu:

image

 

But most of the time, what you see is actually all that you need.  It’s a very clean and simple UI.  Notice in the top left corner it says SETUP.  This is because you are currently in Setup mode.  Once our Sprite has been assembled and our bones have been arranged ( more on this in a moment ), we can then switch in to animation mode by clicking SETUP.

image

In animation mode, its all about posing our character.  Notice SETUP changes to ANIMATE and our interface changes slightly.  Now we have a timeline across the bottom of the screen.  We will get back to that in a moment.

 

Creating Spine Ready Sprites

Creating a sprite that is ready to be animated in Spine is pretty close to traditional sprite based animation with two major exceptions.  First, you cut your image up into several different pieces.  You can draw your sprite as a single image if you wish, but once you are done you need to cut it into several different animatable pieces.  Consider the sprite from the above screenshots:

image

This looks like a single drawn sprite, but it’s actually made up for several pieces arranged together.  If you look in the images section of the hierarchy, you can see it’s actually composed of several different images:

image

 

Again, you can draw your sprite how you normally would, but each animatable piece will need to be cut up to proceed in Spine.  This leads to our second requirement...  you also need to draw parts of the images that are normally obscured.  Again, using this example, even if the upper arm isn’t full shown due to being obscured by the body you still need to draw the entire arm, as the visibility can change as the sprite moves, for example:

imageimage

 

So when drawing the pieces of your sprite, you have to think about the depth as well.  Here for example are all the pieces that go together to make this character:

image

 

Rigging Your Character

Next up comes perhaps the most time intensive portion of working with Spine, rigging you character.  You can think of this as arranging all the various images together to create your character, while defining the underlying armature (fancy word for skeleton).  We will do a very simple skeleton, just to demonstrate the process.  You will notice in the tree view that there is a root node under our skeleton:

image

 

This is the very base of the skeleton and all bones are parented to it ultimately.  From here we need to create a root bone, it’s very common to start from the hips, which is what we will do.  Using the create tool, we will quickly create a simple leg skeleton:

image

Click once to set the start of the skeleton, then move the mouse and click again to set the first bone.  Now move down slightly and set another bone, like so:

image

In the hierarchy I rename the bones to values that make sense.

image

Now that we have bones, let’s attach some images to each.  From the images section you can simply drag the appropriate image onto the bone, like so:

image

You will be prompted if you want to go ahead with it:

image

 

The image is now parented to that bone.  By selecting the image you can now transform, rotate and resize it so it best matches the underlying bone:

image

You can also modifying the bone length by hovering over the tip, like so:

GIF

 

Now repeat for the lower bone, like so:

image

 

You end up with a hierarchy like:

image

 

Extremely simple, but the character is rigged, well, the leg is anyways.

 

Creating an Animation

 

Now that we have a very simple animatable character, let’s now switch over to ANIMATE mode.  In the tree view, you should see a section called Animations.  There may be a default one there, otherwise create one using the New Animation button that appears when animation is selected:

image

image

 

Keyframed animation is pretty simple in concept.  You will notice at the bottom of the screen there is now a Dopesheet view:

image

 

Your animation is composed of a set of “key” frames.  That is, you post your character and take a snapshot of the location/rotation/scale of a given bone, then advance the timeline to a different value and repeat the process.  The computer then interpolates between keyframes to create a smooth animation.  You can turn “autokey” on, so that any changes you make in the editing window automatically set a key.  Otherwise you can manually create the key by clicking the green key to the right of each transform:

image

 

Set a key for the default rotate, translate and scale values, or use Autokey.  Next advance the timeline to say 5, like so:

image

 

Next using rotations, manipulate each bone, like so:

gif2

 

Advance the timeline slightly more, then repeat the process all over again.  You can control the playback of your animation using these simple VCR style controls:

image

 

Here is a very simple and crude kicking animation:

gif3

 

Another cool thing you can do is add Events as part of your timeline, like so:

image

image

Enabling you to create events that can be fired in code, allowing you to incorporate programmatic aspects into your animations, such as playing a footstep audio effect.  We will see this process shortly.

 

Exporting the Animation

Now that we’ve got an animation to use in our game, it’s time to export it.  Here there are a couple of choices. 

image

 

You can export your results as a video, a sequence of images or as data.  If you chose to export as an image you can actually have some rather advanced controls, including generating a texture atlas (directly usable in LibGDX) or sprite sheet:

image

 

With results like:

skeleton-kick

 

This approach can be utilized in just about every single kind of game engine available today.  However, where Spine shines is when you chose to export as data instead.  This is where runtimes come in.  These are essentially libraries or code for the various game engines that enable you to use spine format natively.  Full source is available on github and runtimes exist for most 2D engines available including Unity, LibGDX, Love, MonoGame, Torque2D, Cocos2d-x and many more.  In this example I will be using LibGDX.

 

In this case I’m going to export to JSON and generate a texture atlas using the following settings:

image

 

Now let’s break out some code.

 

Using Spine In Game

As mentioned earlier Spine have several runtimes available on github.  In the case of the LibGDX project, you simply have to copy the code into your appropriate source code folder.  Assuming you created a project using the setup utility, this means copying the contents of esotericsoftware to your core\src\com directory.  Then I wrote the following code, adapted from one of their LibGDX examples.

Make sure that you’ve exported your assets and created the atlas in your working directory, most likely \core\assets.  Then use the following code:

package com.gamefromscratch;

import com.badlogic.gdx.ApplicationAdapter;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.graphics.g2d.TextureAtlas;
import com.esotericsoftware.spine.*;

public class Spine2 extends ApplicationAdapter {
    private OrthographicCamera camera;
    private SpriteBatch batch;
    private SkeletonRenderer renderer;
    private TextureAtlas atlas;
    private Skeleton skeleton;
    private AnimationState state;

	public void create () {
		camera = new OrthographicCamera();
        camera.setToOrtho(false);
		batch = new SpriteBatch();
		renderer = new SkeletonRenderer();
		renderer.setPremultipliedAlpha(true); // PMA results in correct blending without outlines.

		atlas = new TextureAtlas(Gdx.files.internal("skeleton.atlas"));
		SkeletonJson json = new SkeletonJson(atlas);
		SkeletonData skeletonData = json.readSkeletonData(Gdx.files.internal("skeleton.json"));
		skeleton = new Skeleton(skeletonData);
		skeleton.setPosition(0, 0);

		AnimationStateData stateData = new AnimationStateData(skeletonData);
		state = new AnimationState(stateData);

        // Set up an animation listener so we can respond to custom events or completion
        final AnimationState.TrackEntry track = state.setAnimation(0, "kick", false);
        track.setListener(new AnimationState.AnimationStateListener() {
            @Override
            public void event(int trackIndex, Event event) {
                // Check for the "half" event we defined in the editor
                if(event.getString().equals("half"))
                    System.out.println("Half way baby");
            }

            @Override
            public void complete(int trackIndex, int loopCount) {
                // or the complete event (not END!) when done, fire the idle animation instead
                state.setAnimation(0,"idle",false);
            }

            @Override
            public void start(int trackIndex) {
            }

            @Override
            public void end(int trackIndex) {
            }
        });
	}

	public void render () {
		state.update(Gdx.graphics.getDeltaTime()); // Update the animation time.
		state.apply(skeleton);
		skeleton.updateWorldTransform();

        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
		camera.update();
		batch.getProjectionMatrix().set(camera.combined);
		batch.begin();
		renderer.draw(batch, skeleton);
		batch.end();
	}

	public void dispose () {
		atlas.dispose();
	}
}

 

When you run this code...

gif4

 

In the above code example you can see how you can handle an event you defined in Spine.  Otherwise it’s pretty simply to load and play animations on a character developed in Spine.  There is a comprehensive API, I’ve only touched on a very small part of it here due to space (this is already pretty long...).  There are also several features I never got to mention such as free form deformation ( useful for shapes such as capes ), swappable skins, place able props, etc..  If you are doing 2D animation, Spine is certainly a product you should check it.  Spine is by no means the only option when it comes to 2D animation in games, Spriter and Creature are two other popular alternatives.  It is however a very good option.

 

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