Hi Alistair, On 8 February 2013 17:09, Alistair Baxter <alist...@mve.com> wrote:
> We had thought the problem was to do with the database pager, which > declares that it uses additional threads, whilst the Android version of OSG > is said to not support multithreading (at least for rendering).**** > It's likely that threading restriction is down to how the Android provided graphics context was integrated with osgViewer, I haven't work on Android yet so can't talk about specifics, but I'm guessing it'll be using something like GraphicsWindowEmbedded to make it easier to graft the context into osgViewer without providing all the usual support required for managing a full graphics context. Android and the OSG itself should cope fine with multi-threading, and even the viewer side could probably be done multi-threaded if the appropriate GraphicsWindow subclass from provided. The use of GraphicsWindowEmbedded and it's limitation of threading of the viewer won't effect threading otherwise so the database pager should work just fine. The only problem with threading would be if there are other issues on the threading implementation - perhaps OpenThreads isn't full implemented. > However, running out of memory is also a possibility, I shall have a go at > investigating memory limits for the database pager in our app.**** > > One way to test would be generate a database with smaller tile resolutions for the image and elevation data. Run osgdem --help to see all the options available. You can also manage the LOD selection at runtime by setting the viewer's Camera's LODScale. It'd recommend trying this all out on a desktop system first so you get a feel of the effect of various options and then try out on the Android device. Another thing you might want to look at is the situation with compressed textures on the device and exposed by OpenGL ES on the platform, normally on the desktop one uses OpenGL S3TC compressed textures to improve memory bandwidth and total memory usage, you may need to select different compression to work on the mobile device. Robert.
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