Tag: android

Entries for tag "android", ordered from most recent. Entry count: 1.

Warning! Some information on this page is older than 3 years now. I keep it for reference, but it probably doesn't reflect my current knowledge and beliefs.

Pages: 1

Oct 2010

Beginning with OpenGL ES on Android

I've started learning programming for Android. It's (probably) nothing commercial, I just love to learn new technologies and APIs while I have not much experience in either Java, OpenGL ES or mobile technologies at all. The first thing I did was... buying a phone - LG GT540 in my case. It has Android 1.6 (upgrade to 2.1 is scheduled for this year).

Android is a nice platform. Anyone can code for his phone in either Windows or Linux, using Java language (native code development is also possible). To start my coding, I needed to install JDK (SDK for Java), Android SDK, Java version of Eclipse 3.5 (they say Android SDK is not fully compatible with new Eclipse 3.6) and Eclipse JDT plugin to connect them all. Android Developers website does a great job explaining all the steps required to setup the whole development environment so I've came across not so many issues to get annoyed as I often get when installing some C/C++ stuff :)

I've read a bit about the fundamentals of developing applications for Android and I like the API. All these ideas like Activity, Service, Intent, View, Widget, Task etc. seem very well designed. But just like PC game developers learn WinAPI to only initialize an empty window and launch DirectX or OpenGL in it, I went straight to OpenGL on my Android. Android 1.6 has OpenGL ES 1.1, which in turn is the embedded equivalent for OpenGL 1.5. This 3D API has no shaders, so all the graphics has to be done using fixed function pipeline, including MODELVIEW and PROJECTION matrices, 2 textures with register combiners, 8 dynamic per-vertex lights, 1 user clip plane, fog etc. - something like on the old good GeForce 2 MX :)

It's easy to start using OpenGL for someone who has experience in DirectX because all the concepts that are so diffcult to understand at the beginning of the game programming adventure stay the same - like 3D coordinate system, vertex, triange, matrix, texture and so on. Some things are only reversed - textures are addressed from left-bottom corner in OGL, matrices are stored in column-major order, matrix multiplication is right-to-left like Point2 = Xform2 * Xform1 * Point1, post-projective space is -1..1, -1..1, -1..1, coordinate system is right-handed so Z points to the viewer, angles are given in degrees, counterclockwise oriented triangles are considered front-facing by default and so one. Some objects have also different names, so in OGL there is "model" not "world" matrix, "fragment" not "pixel" operation etc.

Here is the list of Internet sources I already know about and I've been learning from:

Now you can expect more entries about Android development on my blog :)

Comments (3) | Tags: android opengl mobile | Author: Adam Sawicki | Share

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