Crossing the meridian

Since I installed fsx my test flight after any config changes has been to take off from London city airport EGLC and fly west over the millennium dome, along the Thames to heathrow.

The frame rate always takes a hit after takeoff which I attributed to the scene complexity with the dome and  canary wharf sky scrapers. The power of association!  However examining the scene in the intel fpa tool showed this was nonsense. The dome is a single drawcall, which is no more cost than fsx spends drawing a couple of trees somewhere near fulham broadway.

I used system internals process explorer to watch what happened.  As the frame rate slows there in indeed a big spike in disk reads.  Drilling down in the tool I could see airport bgl files for  LosAngeles  and malmo?

So I read the sdk!  It explains that traffic is implanted in a block of  9 squares surrounding the aircraft and these are at the equator approx 60 miles square each.  Clearly then they must be based on degrees of latitude and longitude

There is one other place of interest near to the dome!  Greenwich “home of the prime meridian”.

So the slow down has nothing to do with the London scenery, it’s fsx implementing traffic for the next three squares  located  2 degrees west.  That includes Southampton, Birmingham and some other midland airports.

About stevefsx

I don't use FSX that much. But I am very annoyed when it doesn't work properly!
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2 Responses to Crossing the meridian

  1. stevefsx says:

    I plan to try moving the airport files off my SSD onto a slower disk to see if that lessens the impact!

    What is really needed is for the Traffic Add Ons to monitor position and inject traffic slowly – I don’t think that the product I use has a runtime element – it provides aircraft models, paint and a flight schedule editor.

  2. Paul Johnson says:

    I take it you are using Ultimate traffic, then? I dumped this a long time ago because of that injection “stall”, and then switched to MTX – but I only fly PNW nowadays, and rarely in the UK. This will be interesting to see how OrbX handles this when they begin dev of the UK.

    This is a great series of posts, Steve, and I’m only sorry I didn’t spend more time with C++. I have over thirty years in IT, but spent the last fifteen as a (Unix – Solaris) SysAdmin, and my “expertise” is limited to shell scripting. I’d love to add to, or reinforce your work – two heads are better than one!

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