Screenshot saturday

Happy Noel!

Happy Noel from the Discretion team!

Noellephant says hello.

Libgdx efforts, and Chapter 1 almost feature complete!

Yesterday I did lots of tidying up of my codebase, bringing the bits I wanted to add to libgdx up to that project's standard. The end of the day saw me commit a lot of stuff - read the libgdx blog for what I got up to.

Today saw a lot more tidying up and polishing, with Chapter 1 looking almost feature complete, and a decent start to loading and saving. I'm very happy with my progress this week, and am looking forward to recruiting some beta testers in the near future.

Here's another screenshot! Look out for an introduction to the main characters soon...

Discretion's first pre-alpha screenshot

So, despite a crazy week which included getting stranded in the UK due to the bad weather, Google breaking ADT (rendering me unable to do any coding) with the latest Android release, internet outages due to our ISP and other setbacks, I've actually made some progress on the game! Enough that I'm willing to release this very pre-alpha, very basic screenshot of the main character and one of the party characters wandering around Atnar Castle. More will follow in the coming weeks.

Modelling with DeleD

Some thoughts on a workflow within DeleD, the world editor I'm using to build my levels with for Discretion.

1. Build world

2. Triangulate world (divide non-triangular meshes into triangles)

3. Apply materials and fix U/V mapping where necessary

4. Export

It's important to do as much modelling as possible in 1. before proceeding to the next steps, because the easiest way to ensure everything is triangulated once and only once is to select all objects then do triangulate. It's necessary to do 2. before 3. because U/V mapping a non-triangular polygon doesn't always work too well.

The Wavefront .obj exporter for DeleD has an extremely useful 'scale' option which allows you to model at the scale DeleD was designed to be used at instead of at real world (game) scale (mine is 1 unit = 1 meter which in DeleD is way too zoomed in). The triangulator in the exporter is broken however, so make sure you triangulate using the geometry toolbox instead.

Hope this helps someone!

Getting FloatBuffer data: BufferUnderFlowException

When getting FloatBuffer data from a mesh, you must be sure to rewind your buffer before copying it if you already have before. I was iterating subsets of vertex data for the same mesh (I have "submeshes", which are equivalent to Wavefront .obj groups or objects) and trying to get the vertex data for each submesh for some processing, but the second iteration I was getting a BufferUnderFlowException.

It took me longer than it probably should have to realise I needed to "rewind" the buffer so I could copy the data again. To do this simply call FloatBuffer.position() with zero to set its internal position back to the start.

Of course if you need to be performant, you probably shouldn't be copying it twice anyway... :)

Java.String memory leak

Or "How I just saved myself 3 meg of precious Android heap memory".

I always glazed over whenever I came across how Strings are implemented in higher level languages. The most important advice I ever came across concerning them was "use a library that does all that string stuff for you". Of course I can make reasonable assumptions about how Java does strings:

1. There's a char buffer somewhere in there storing sequences of raw characters

2. It probably does something clever with them along the lines of the same way I do textures

So what happened? A loader parses an entire object file into a string, then passes a tokenized element of that string into an object as the object's name. It all seemed fine till I ran the Eclipse Memory Analysis Tool, when I found at the top of my memory usage hitlist a bit more than 3 megabytes of char data. As in, a couple of raw char[]. Full of, guess what? My entire object file.

"What's happened here?", I thought, stroking my chin. A closer look at my object in the debugger (a Submesh) revealed that sure enough, its name (supposed to be something like "grp 1"), which is a String, has the entire object file in its buffer. The String object stores an offset and length into the character buffer. The garbage collector looks at the 3 meg buffer and says "well, this Submesh object here still has a reference to this sequence of data, so I can't delete it!".

The fix is trivial: construct a new string from the passed in string, which makes a new buffer and frees up the old one for the GC's unreferenced memory hit squad.

I thought I'd post this because without running the MAT I never would have known I was leaking 3 megs of memory. It's worth checking.