Re: Reducing airports polygon count

Erik Hofman wrote:

> Dale Edmons wrote:
>
>>> It would be interesting to hear how your IG natively models 
>>> airports/runways.  How do they build/draw the runway numbers and 
>>> other markings.  Are they part of the texture, or are they overlayed 
>>> as separate polygons?
>>>
>>
>> The runway's are polygons--often one rectangle on these old systems.  
>> (This
>> is one thing I'm trying to change and am happy that FGFS uses more 
>> accurate
>> runway modeling.)  The stripes etc.. are polygons on top of the 
>> runway.  The
>> textures essentially modify the color of the base polygon to provide 
>> things
>> like skid marks in the landing zone.
>
>
> I was just thinking, haw about projecting the airport layout onto 4 
> (1024x1024) textures and project those textures on a very reduced 
> airport terrain?
>
How does this compare to how it is currently being done?  I have to 
admit I don't fully understand how things work now.  I've already 
substantially reduced the surrounding terrrain.  If I understand 
correctly, the airport is built independently and the surrounding 
terrain clipped and adjusted to match the airport.  Also, if I 
understand Curt's description, the airport polygons are build to match 
the textures and this caused the high polygon count.  If the repeating 
textures were duplicated and placed into new longer mid-textures the 
polygon count could be reduced to match the terrain instead of the texture.

This might also help others who are having problems with frame rate.  
Airports are currently very dense in terms of polygon count, and 
somewhat flat.  Reducing the polygon and texture count would bound to 
improve FGFS's framerate too.  As long as result matches the curve of 
the actual airports I'd say this is a good approach.  This might yield 
significant frame-rate increases, especially at airports such as KDEN, 
KLAX, KORD, and others with multiple runways.

I don't know if projecting the airport onto the terrain is a valid 
approach.  Airports often represent a unique area modified to accomodate 
landings.   For example, at KSEA they have been hauling dirt for about 
two years to build a third runway.  The airport is on top of a hill, so 
to speak, and a simple projection would warp it terribly and not have 
the sudden drop at the ends.  Landings would be more like controlled 
crashes.


Dale

> Erik
>


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