David,

Very cool ... it would be nice if we could hide the fade in of the
objects a bit better, but I'm not sure if there is an easy way to do
that.  Vega/performer supports something called "fade level of detail"
which uses alpha to fade in the object (or fade between levels of
detail.)  But even so, very cool.

We need a farmer and a tractor for the farm fields here in MN.  If the
farmer's name was "Nic" then we could have a "Scenic overlook, he's
outstanding in his field."  Ok, sorry about that, it was painful to
say, even for me. :-)

Regards,

Curt.


David Megginson writes:
> Over the weekend, I finished my first take on dynamically-placed
> scenery objects.  I'm attaching two screenshots:
> 
> 1. Approaching a city over some woods, with a pasture in-between.
> 
>    http://www.megginson.com/flightsim/dynamic-01.png
> 
> 2. Sitting on a lake, pretending to be a floatplane.
> 
>    http://www.megginson.com/flightsim/dynamic-02.png
> 
> This is not, primarily, designed to be eye candy (well, only a bit of
> it is).  Dynamic objects like buildings and trees serve several very
> important purposes during VFR flight:
> 
> a. They give some indication of altitude AGL and groundspeed.  Even at
>    low altitude Trees get very small very fast; if they're big and
>    there's not a runway in your windshield, add power and pull up.
> 
> b. They provide aiming points for turns and straight flight (i.e. to
>    turn 90 degrees, look off your wing, pick and object, and then fly
>    towards it).  For example, it is much easier to hold a compass
>    heading if you turn to the heading, pick an object off the nose,
>    then keep that object off the nose than if you constantly chase the
>    compass around.
> 
> c. (not so nice) They cause very confusing illusions because of drift
>    when flying near the ground.  It is easy for a pilot to get into a
>    spin or spiral by banking too steeply because the plane doesn't
>    seem to be turning much.
> 
> Right now, I've added only a few dynamic object types, so it's a bit
> monotonous.  Over the next week or two, I'll try to introduce a
> greater variety of buildings and trees, at least, and maybe a few pure
> eye-candy things like boats out in lakes.  All non-billboarded dynamic
> objects also currently face the same way; I plan to fix that in the
> next day or two.
> 
> I've made very aggressive use of LOD to keep the framerates up; for
> example, trees are visible only from a range of 2000m and large
> buildings from 10000m; I also slap a range on all the objects on each
> triangle or fan, so that plib won't have to do hundreds or thousands
> of LOD calculations for objects that are far out of range.  Even then,
> trees cannot be too dense.
> 
> NOTE: Dynamic objects are off by default.  After you update the
> FlightGear and base-package CVS, you will have to set the property
> /sim/rendering/dynamic-objects to true to see anything (if you change
> it during the program run, you'll have to reload the scenery).
> Depending on the terrain, visibility, and altitude AGL, you may
> experience slow framerates for a few seconds while FlightGear places
> dynamic objects on all the tiles; just wait, and everything will speed
> up again shortly.
> 
> Special thanks to Curt, whose ground-lighting code I
> stole^H^H^H^H^Hused as inspiration to calculate object placement.
> 
> 
> All the best,
> 
> 
> David
> 
> -- 
> David Megginson, [EMAIL PROTECTED], http://www.megginson.com/
> 
> _______________________________________________
> Flightgear-devel mailing list
> [EMAIL PROTECTED]
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-- 
Curtis Olson   IVLab / HumanFIRST Program       FlightGear Project
Twin Cities    [EMAIL PROTECTED]                  [EMAIL PROTECTED]
Minnesota      http://www.menet.umn.edu/~curt   http://www.flightgear.org

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