On Mon, Sep 3, 2012 at 11:58 PM, Stuart Buchanan wrote: > I've (finally) managed to get a prototype running using an instantiation > of a shared geometry rather than a huge single object per tile. > > So far the results are promising. My standard test is at KSFO with the > c172p, waiting until the intial set of tiles is loaded with standard weather > conditions (e.g. no excessive visibility). > > With random buildings switched off FG uses ~1GB memory. With v2.8.0 > random buildings, it's 2GB. With instantiated buildings at present it is > 1.5GB. > > At KLAX, it's down even further, from 2.7GB to 1.6GB. > > I've not noticed any frame-rate impact. > > There's still quite a lot of work to do, but I hope to have this available > before the next release.
This work is now checked into next/master. You'll need an updated simgear and data to see any effect. Basically, I've moved to using a scheme very similar to that of the trees, where there are a small number of buildings created, and then instantiated multiple times. The technique relies on a vertex shader, as the final position and rotation of the building are passed in on the gl_Color vector. This in turn has meant that I've been forced to create new version of various vertex shaders. It might be possible to clean that up by having a new parameter to existing shaders indicating that position/rotation information is in gl_Color, but I haven't investigated that option in detail. There are three known regressions from the previous implementation: - The reflection map appears to be broken, and is currently switched off. I suspect this might be because the binormal or tangent are not being calculated correctly. - The buidings do not cast shadows in Rembrandt, though other objects _do_ cast shadows on the buildings. I don't know the reason for this. - At high building densities and certain angles of view, one can see gaps in the building placement where the edges of the scenery triangles go. This is unfortunately inevitable, as we have less sizing information during placement. If anyone with shader/effects knowledge has the time to look at the first two of these problems, that would be wonderful. Feedback/comments appreciated as always. -Stuart PS: With a building density of 4 at KSFO I have 1.6GB peak occupancy. That compares to > 3GB previously. ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
