Open code and you

doom

Moving some of my projects to the wild, I mean to GitHub, has made me realize what others already knew, much of the software we use everyday is open source or has some roots there. Be honest, peeking to someone else’s software is great. As to my own experience I started learning programming as a child reading the source code of the Doom Editing Utilities (and that probably shifted and twisted my understanding of computers for my entire life). This concepts of seeing others work and learning from it is a hidden fact that affects our life in for example every gadget we use (read Android/iOS). But not only to learn but to understand what a piece of software does, its source code is the ultimate documentation. If you are using a third party library, ask for its source code and peek at it when needed. At Video Stream Networks we made a similar approach, we had our domain logic code written in C++ every time we had to tune it for every customer’s workflow it made us feel miserable. After we moved our domain logic into Casper, a Domain Specific Language for the media and broadcast world, our customer can not only peek at what our app does but understand and fine tune it themselves.

Thanks to GitHub and the Open Source Community, ShadingZen Engine is slowly maturing. The GitHub repo received a pull request with some great changes. The project now has Maven build, the structure is more clear with all the examples and documentation centralized in just one repository and the eclipse requirement has been removed (This last point allowed me to try out IntellIJ IDEA which so far I find as a really good java IDE).

Yes, open source level editors as well a robust designed and extensible engine was behind the success of DOOM, the very same that made some of us programmers.

Towards ShadingZen 1.0beta2

Development of ShadingZen is approaching version 1.0 beta 2 and a new minor update has been rolled out and ready to be cloned/forked by you at ShadingZen’s GitHub repository.

The primary goal for this milestone (v1.0 beta 2) is to provide better documentation, ranging from API documentation to useful examples for the wiki.

Secondary goals are to improve performance, mainly in areas where we can use object pools to avoid garbage collection frame rate drops. In fact, RenderTasks have been refactored and now use a global shared pool manager which creates and reuses RenderTask objects. This gives a performance boost but increases memory usage.

ShadingZen is a 2D/3D Engine for Android OpenGL ES 2.0 and is open source under the MIT License.

Android realtime performance tips

Embedding programming has never been easier after the introduction of modern mobile APIs like Android SDK and iOS SDK. Nevertheless for realtime applications new areas for potential bottlenecks may arise as those extra layers add more complexity to your application.

A clear example may happen with the Dalvik GC (Garbage Collector), which coupled with a realtime 2D/3D Engine generating many objects for each frame, will (for sure) showcase frame drops when the GC hits in. This is hard to solve as Java makes really easy to create new objects that encapsulate your required functionality but hides from you how and when the memory will be collected. Hey! it creates objects everywhere, for iterators, enums, sorting alogrithms…I personally think Dalvik needs some improvement in memory management areas but meanwhile we just need to avoid those problems and minimize them as possible.

Dont create objects! No, seriously, don’t create new objects in your game loop. Use object pools as much as possible. This is an area ShadingZen engine is improving and is one of the reasons you should always create new actors using the “spawn” method.

Don’t call your own methods, use the objects properties within the objects code and use methods to access functionality from outside. Also avoid using getters and setters, but pack functionality in just one method call instead of using the getted property from outside. For example if you want to make an actor explode you may need to compute explosion velocity and actor final destination from outside. Instead create a “makeExplode” method for that and compute everything within the object code. Dalvik makes calling methods slow.

If you are using OpenGL ES avoid changing states, pack drawing calls sharing the same state and run them at once.

DDMS is your friend. I know how much you hate its awkward interface but you need it, profile often!

Check this paper as it contains basic guidelines to avoid performance bottlenecks in your realtime applications: http://dl.google.com/io/2009/pres/WritingRealTimeGamesforAndroid.pdf

Performance is an area the next version 1.0-beta2 of ShadingZen is receiving much love.

Development of Kids 3D Cube

I’m happy to announce that I have release my newest creation, Kids 3D Cube for Android:

https://play.google.com/store/apps/details?id=org.traxnet.kidscube

For this game a new 2D/3D engine optimized for multi core phones was created, targeting OpenGL ES 2.0, so It won’t run on old Android versions (below 3.2.).

A few interesting things about the 3d engine: It employs an smart task scheduler to parallelize work among all cores. It also has a lazy resource loader and few other interesting functionalities that I believe are a good starting point for upcoming titles.

I have to confess that mobiles GPUs are challenging for the limited set of resources, but high rewarding when your little phone starts showing up your glorious shaders on screen! 😉 A tip: minimize bandwidth usage, keep us much on GPU side and reuse it as much as possible. This is a big win on low-end phones.

I’m actively working on solving a few issues and adding new content to the game, stay tunned!

You can visit Kids 3D Cube fan page at Facebook here: http://www.facebook.com/Kids3dCube

Android development tips – Gifagram project

For the past months I have been reading the Android SDK, trying out it’s OpenGL ES 2.0 capabilities (check my Github project ShadingZen) and was really impressed with the overall API quality. It’s easy to get things done, and its integration with Eclipse helps too. Current top devices are computing crunchers!

I went thinking I could play a bit higher by developing some application for Android, and that’s how we came with the idea of Gifagram app.

Gifagram.com promo image

The idea behind it is to enable the user to create stop-motion or animated GIFs directly from her Android device. GIFs are easy to share, doesn’t take much bandwidth and some very creative people manage to communicate really stunning stories in this format.

Not everything was easy tho. The camera API in android is really quite undocumented and its behaviour relies completely on the underlying hardware implementation. Retrieving useful information from the beta-tester devices was also cumbersome (to the point that was much easier to just take the terminal to the mac and just debug it directly than to take and read the logs).

Some tips on android development:

  • Think the user workflow within the application and minimize user taps and input steps. Make it simple, vertical application vs “The killer app”.
  • Prototype the application with simple buttons and don’t waste time until the domain logic is really working.
  • Try your software on every android device you can get. This probably should go on top of your list.
  • If you plan to create a free and a paid version, develop with a single application and when you are ready to go to market, convert the project to library and reference it from your free and paid android projects (check this: http://developer.android.com/guide/developing/projects/projects-eclipse.html).
  • Android market share is growing, but it’s fragment in devices and versions. Android 2.2 and 2.3 are currently in almost 90% of the devices out there, develop with this in mind.
  • Avoid NDK unless you are really sure about any performance boost that may gain. For gifagram we had to use it no matter what and was a bit tricky at some points.
Side note: There are a lot of useful resources, for example stackoverflow.com is a great place to look.