Thursday, July 17, 2008

Summer and release

I'm currently away on vacation, touring Sweden and visiting relatives, but just before I left I managed to push version 0.5.3 of Ember out. My initial goal for this release was to make sure that all of the nice media that Jayr has provided should come to better use. My plan was to first work on an updated world, a larger piece of terrain which were more suited for the way Ember handles LOD and which also would use more of the media through the use of new entity types. The idea was also that by working on a new world, authoring it through Ember, I'll be better able to find and fix those places where the authoring tools were lacking.
And this plan worked very well. The first thing I enhanced was the terrain editing tool, which previously only allowed one to edit a single base point at once, but now allows you to edit a wide swath of base points at once. This makes it much more easier to alter large expanses of terrain. I've also added an automated function which generates atlas entity type definitions from existing meshes. A lot of the media that Jayr has provided is lacking corresponding entity types, so I needed an easy way to quickly create entity types, using the new meshes as blueprints.

However, when working on the new terrain I quickly realized that Ember wasn't very efficient in the way it handled memory. Since my development box has quite a lot of memory I hadn't really noticed it, but as I now was trying out different very large terrains it became noticable. I thus had to spend some time going through all of the instances in Ember where it either used memory in a wasteful way, or just plain and simple leaked it. In the end I think I managed to squash almost all of the places though, and as a result Ember now doesn't use nearly as much memory as before. A lot of the memory used however is texture and mesh memory, and I need to take a look at how I can talk to Ogre about better free up textures that aren't currently used. There will probably need to be a texture collecting task running at a certain interval to make sure that unused textures are freed.

The work with the memory cleanup took some time, and I had to revisit my original plan of releasing 0.5.3 together with a new world. I do want to do more regular releases, so I didn't want to wait too long between 0.5.2 and 0.5.3. In addition to that, there were new releases of both Ogre and CEGUI which both weren't compatible with 0.5.2. If we waited too long, we would run the risk of more and more people trying to compile 0.5.2 against these latest releases and failing.
And finally I wanted to do a release because it would provide an opportunity for the GSoC students to sync up with the trunk, preventing their trees from lagging too far behind it.

So in the end I pushed 0.5.3. In the rush to get it out I completely forgot to test it with Lua 5.0. The issue was picked up by Oliver Lehmann when creating ports for FreeBSD. Luckily he was able to update CEGUI to also use Lua 5.1 without breaking any other ports. Lua 5.1 has some nice language constructs which we can't use as long as we also provide support for 5.0, and we'll be looking at whether it might be possible to completely drop support for 5.0. 5.1 has been out for quite some time and I think all modern distros provide support for it, so it shouldn't be any problem.

Looking ahead, the Summer of Code is now entering the final phase, and we'll hopefully be seeing working implementations of the student's projects. It's already looking good, and I'm hoping to be able to merge those projects that are finished into the trunk in time for release 0.5.4, which I aim to have ready no later than three months from now.
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