FlightGear Newsletter September 2010: Difference between revisions

The [http://www.phy.duke.edu/~trenk/files/local_weather_fgfs2.0.0_v0.85.tgz version 0.85] (also on [[Git]]) of the [[A local weather system|Local Weather package]] is out - with new cloud types and textures and most importantly a significant performance gain over previous versions. There is a new menu to allow the user at runtime to specify cloud visual ranges, so that the impact on framerate can be adjusted to the situation.

[[File:new_weather_dialog.png|thumb|250px|The new weather dialog]]

[[File:AIWingmenandAITanker.jpg|thumb|250px|AIWingmen and AITanker]]

[[File:FlightPlan_Generator1.png|thumb|250px|A taxi-script example]]

[[File:Water shader Ju 52.jpg|thumb|250px|[[Junkers Ju 52]] flying over a lake in the French custom scenery.]]

[[File:nike missile site3.png|thumb|250px|One of three sites.]]

Jack Mermod has begun modeling Historical Nike Hercules Missile Sites. They will all be in the Bay Area. These sites were the last stand of defense in the event of a Soviet bombing. You can still find evidence of these sites today, and they are a important part of history. Each site has a helipad, in hopes of attracting helicopter pilots to come and explore the sights. So far there are three sites that have been made and placed into FlightGear, and the plan is to make 12. The sites will hopefully be available through TerraSync soon, but for now you can [http://www.flightgear.org/forums/viewtopic.php?f=5&t=9521 watch this forum topic] to see updates for the sites and download them.

[[File:LOWI_oamtc_helicopter_base.jpg|thumb|250px|Innsbruck ÖAMTC helicopter base]]

[[File:VadoLigureHarbor.jpg|thumb|250px|Vado Ligure Container Ship Terminal]]

[[File:Moveable helipads.jpg|thumb|250px|Moveable-helipads in FGFS can be controlled in many ways. It is a feature which commercial sims like MSFS or X-Plane don't have yet.]]

OOP is all about creating "things" (i.e. a cloud) with "actions" (transform,draw,update) (or "messages"). Where a class (or hash in Nasal) is the "template" for a "thing" containing a number of member fields. So the class only describes the "layout" or properties of objects that can be created. To actually use a class, it has to be "instantiated" which means creating an object using a specific "template class" (or even several different classes).

These member fields can be variables (e.g. lat, lon, alt) or functions (setAlt, setPos). And the actual instance (cloud[n] in the property tree) of such a thing is then called an "object". Functions that work with instance specific state are called "methods", they may refer to instance specific state using a "self reference" (me) in Nasal, that ensures that access to a field or method is using the right instance specific data.

In OOP, internal state is managed by wrapping everything in a class using accessor functions for modifying and getting internal values. So internal state would in turn only be modified by an abstract interface: class "methods", instead of directly accessing class-internal fields.

Classes may be composed of other classes, i.e. a "cloud field" class would in turn contain "cloud" classes. This is then called "composition".

[[Image:Maui03.jpg|thumb|250px]]