As part of our ongoing “Closer Look at” series, today we will be looking at the Babylon HTML5 3D game engine. These posts are a mashup of a review, preview and tutorial aimed at giving you a quick overview of what to expect from the game engine in question.
If you prefer, there is an HD Video version of this post.
BabylonJS is a very code centric game engine, with very few tools. There is no level editor like PlayCanvas that we looked at last week. There are however 3D model exporters that we will see shortly. In terms of functionality, BabylonJS is most similar to Three.JS which we’ve also looked at earlier.
The following is Babylon’s description of themselves:
About babylon.js
Babylon.js is a 3D engine based on webgl and javascript. It supports the following features:
Complete scene graph with lights, cameras, materials and meshes
Collisions engine
Physics engine (thanks to cannon.js)
Scene picking
Antialiasing
Animations engine
Particles Systems
Sprites and 2D layers
Optimizations engines:
Frustum clipping
Sub-meshes clipping
Hardware scaling
Selection octrees
Offline mode (Assets are saved locally to prevent reloading them)
Incremental loading
Binary compressed format
Hardware accelerated instances
Standard material is a per pixelmaterial that supports:
Diffuse lightning and texture
Ambient lightning and texture
Specular lightning
Opacity texture
Reflection texture (Spheric, planar, cubic and projection)
Mirror texture
Emissive texture
Specular texture
Bump texture
Up to 4 lights (points, directionals, spots, hemispherics)
Custom materials
Skybox
Vertex color
4 bones per vertex
Fresnel term for diffuse, opacity, emissive and reflection
Special FX
Fog
Alpha blending
Alpha testing
Billboarding
Fullscreen mode
Shadow Maps and Variance Shadow Maps
Rendering layers
Post-processes (blur, refraction, black'n'white, fxaa, customs...)
Lens flares
Multi-views
Textures:
Render target textures
Dynamic textures (canvas)
Video textures
Compressed (DDS) textures
Cameras:
Arc rotate camera
Free camera
Touch camera
Virtual Joysticks camera
Oculus Rift camera
Gamepad camera
VR Device Oriention camera
WebVR camera
Follow camera
Meshes:
Mesh cloning
Dynamic meshes
Height maps
Bones
Constructive solid geometries
Import:
Babylon scene file can be converted from .OBJ, .FBX, .MXB
Exporter for Blender
Exporter for Cheetah3d
Exporter for 3ds max
Support for drag'n'drop
Assets manager
Our First Application
Since this is a code focused engine, this is going to be a code heavy example. Let’s just right in with an example Babylon application:
The HTML is simply a container for a canvas element named renderCanvas. The <script> portion is the heart of the application. Essentially what we are doing here is making sure that the Babylon engine is supported in the browser we are running, if it is we get a reference to the canvas and create our Engine class using it. We then use the engine to create a Scene object, which is the scenegraph for our game.
Next up we create an ArcRotateCamera. This is a camera with built in orbiting functionality, allowing us to orbit around our scene without writing any additional code. It’s worth pointing out that Babylon is a Y-up world, in which the Y axis represents up and down, while Z-axis represents depth in and out of the screen. One our camera is created we position it slightly back along the Z axis, pointed at the origin. Finally we make our camera active in the scene and give it control.
Finally we populate our scene. All we are doing is making a simple Sphere. We then make a simple material for our sphere, in this case an emissive red material. Being emissive means that the material itself gives of light, so we don’t need to add any lighting to our scene. Finally we register our RenderLoop, which is the heart of your application and is called every frame. In this case we simply render our scene with a call to render().
When you run this code you should see:
Working with 3D Models
One of the big challenges when working with a 3D model is bringing in 3D assets. If something is going to go wrong, this is generally where it happens. Let’s take a look at the process with BabylonJS.
There are a couple exporters available for Babylon here on Github.
Today I will use the Blender exporter.
First we need to download the fills from Github. To this day I still don’t know why Github haven’t made “Download this folder as a zip” an available option, but sadly they haven’t. You can either download the files manually ( be sure to use RAW ) and recreate the directories yourself. Or you can use SVN to make the job easier. These are the files we want:
Available at https://github.com/BabylonJS/Babylon.js/tree/master/Exporters/Blender.
In a terminal or command prompt, create a temp directory, cd into it and execute the command:
svn checkout https://github.com/BabylonJS/Babylon.js/trunk/Exporters/Blender
Basically you replace "tree/master" with "trunk”. The results should look like:
Now you want to copy these files and directories to your Blender addon directory. In my case, on MacOS running Blender 2.74, the directory is:
/Applications/Blender.app/Contents/Resources/2.74/scripts/addons
Of course this directory will vary from version to version and platform to platform.
Now we need to enable the Exporter in Blender. Launch Blender.
Select the File Menu ->User Preferences
Now select Add-ons at the top, Import-Export on the left, locate Babylon.js and enable it. Finally ( optionally ) click Save User Settings if you want this change to persist the next time you load Blender, or you are going to have to do it all again each time you start again.
Now lets model, UV map and texture a simple 3D Cube for exporting. I am not going to cover the process here, so if you are unsure how to perform this step, be sure to check the video version for more details. The key thing is, we need to export the model AND the texture. I saved it using the name untitled.png. We want a model looking something like this:
Now it’s time to export. Simply select File->Export->Babylon.js
The available options are rather limited, go with the defaults.
This will generate a .babylon file. Copy this file and your texture to the root of your project directory. Your project directory should look something like this:
You may notice the .manifest file. This is simply a descriptor of your file, I added it simply to get rid of a warning. The contents look like:
More Coding
Simply name the file the same as your .babylon file with the additional extension of .manifest. Now let’s take a look at the code to load a single model:
The top is simple HTML, basically we want to use 100% of available space. The most important part was the canvas tag renderCanvas. Of course we also imported the bablyon.js files. Below the HTML is the heart of our game.
First we are basically checking to see that the browser we are running in meets BabylonJS’s requirements. Assuming it does we get a reference to our canvas tag by id from the DOM, then use it to create an Engine object. We then called BABYLON.SceneLoader.Load(), passing in our 3d object to load, a reference to the engine and a function to call when complete. This is an async callback, and execution continues with the functions callback.
When the object has finished loading we create a camera, position it, then create two hemispherical lights pointing from the left and the right. In our runRenderLoop function we call the render method on the scene the Load() method returned.
Run this code and you should see:
In this example however, we are actually bringing in the entire Blend file, including the camera, lights and all meshes contained. What if you instead just want to bring in a single mesh instead? Don’t worry, that’s pretty simple too...
Here instead we use the ImportMesh() method of SceneLoader. This callback returns a meshes array, in which case we position the first entry in our game world. I suppose it’s important to note, but you can provide several other callbacks, I was just lazy… there are callbacks for errors and progress as well.
Basically you will use Scenes to load your level, then load individual Meshes, etc… to populate it with additional or more dynamic objects. Speaking of scenes, one thing worth point out ( and demoed in the video ) is that a number of Blender properties are supported in the BabylonJS output process. This includes things like cameras, lights ( with full property support such as range, colour, etc ) and physics properties are all exported. This would make Blender (or Max, Cheetah, etc…) your primary level editing tool. When tested it works remarkably well.
For example, I downloaded a random model off the web. I duplicated and instanced it a couple times to make a simple level and added a red point light. Here is my hastily thrown together scene in Blender:
Now lets load and render the same scene in BabylonJS:
Obviously the grid everything is resting on is behaving a bit differently, but otherwise… that’s impressive. I didn’t have to mess around with this object at all, simply downloaded, loaded in Blender, converted and added the babylon and textures to the project and done.
So that’s a bit about coding and the art asset pipeline when working with BabylonJS, what about the other stuff…?
The Documentation
This is an area that is both good and bad. The primary source of documentation is the wiki available here. Let me just start by saying I HATE the wiki software they used. It’s just annoying in a thousand little small ways. For example, clicking column headings on the left hand side often brings you to pages like this...
It’s a minor gripe, but it really annoyed me. Even little things like resizing can cause the software to go completely stupid, oh and you can’t even resize the width of the sidebar... Wiki’s are something that have been solved… so why use this subpar implementation? Anyways, back to the actual contents…
The Tutorials first… there are a good collection of tutorials, in both Text and Video form. Some are hosted locally, some on external sites. The breadth of topics is solid though:
Truth is, I almost never needed them, thanks to the playground. The playground is a collection of samples that you can play with live and contain most of the examples you would need to get started. If you are a sample code focused learner, you will love this.
You can access the playground here.
There is also a class reference that is like the rest of the documentation, both good and bad. Generated documentation is another thing that has mostly been solved… and it’s another area where BabylonJS decided to use a different solution, one that is vastly inferior to the norm.
It can be access from the left hand sidebar, and is subject to the same screwy navigation as the rest of the wiki… clicking column heads brings up a useless page to the right. You need to dig down on the left to the class you want, and it will then appear on the right. Unfortunately, and I really missed this, there was no inheritance based information in the documentation, like you get with other offerings. Therefore figuring out class hierarchies are a great deal more difficult than they need to be. The actual documentation itself is fairly solid, generally having the information you need in sufficient detail, an area where many of these projects fail hard.
There is however this page. It’s a hand curated list of the most popular classes… although they didn’t always use the same class names ( often short hands ) which adds unneeded confusion.
When starting out however, this is probably a page you will have bookmarked on a permanent bases.
Finally there are the forums, like Phaser and Pixi, they are hosted on Html5GameDevs Forums. This is a good community with good participation. Oddly though, I find it does really poorly with Google searches, so if you need help on a topic, you are often best going to the forums and searching directly. This was true of Phaser as well… not really sure what the issue is.
So basically the contents of the documentation is fine, good even. The Playground is exceptional. The wiki/reference software they use on the other hand is just bad and hurts the whole experience.
Other Tools
So, Babylon is a very code focused engine, there is no integrated editor, font creation tools, animation tool, etc… However there are a couple tools that you should be aware of, even if you don’t work in BabylonJS!
There is the Material editor. For programmatically creating materials that can be previewed in real time:
There is the shader editor (CYOS), enabling you to create GLSL shaders, tested in real time. A handy tool, even if you aren’t working in BabylonJS.
There is also the Sandbox, for testing your assets out. Frankly it never worked for me… Granted I didn’t really look into it all the deeply either.
Conclusion
As I’ve said a number of times, BabylonJS is a code focused engine. It provides the low and medium level plumbing to enable you to create a 3D game. Due to the restraints of time, page length and my own experience, I obviously can’t deep dive into the technical abilities of this engine. This is a shame, as I believe it’s at that level that this engine really starts to shine. That said, its an approachable, clean, relatively complete 3D game library/engine, that if you prefer to work in your CAD program of choice, is a great pairing. If you are looking for more of an editor experience, you should certainly look elsewhere.
As is important with these types of projects, the community behind Babylon is good, the documentation/tutorials/materials are all quite good in content, but could use a great deal of polish in presentation.
If you are looking to make 3D games using HTML, should you consider Babylon? If you don’t require an editor… certainly!
The Video