Ampere K. Hardraade wrote

> Sent: 26 July 2004 03:13
> To: FlightGear developers discussions
> Subject: Re: [Flightgear-devel] Spitfire
> 
> To create smoke, we will need two things: smoke emitter and smoke object.
> 
> The smoke emitter will allow the user to set the following properties:
> - X, Y, Z coordinate relative to the aircraft.  This is the location at
> which
> the smoke objects will be created.
> - vector at which the smoke is emitted.
> - initial velocity of the smoke relative to the aircraft.
> - radius of the smoke.
> - temperature of the smoke (useful when velocity is zero).
> - density/opacity of the smoke.
> - illumination value of the smoke in RGB.
> - color of the smoke.
> - time it takes for the smoke to become visible.
> - rate at which the smoke will dessipate.
> - time it takes for the smoke to lose illumination.
> - a boolean variable to control the state of the smoke emitter.
> 
> When the smoke emitter is enabled, it will keep creating new smoke
> objects.
> These new smoke objects will have the following properties:
> - current X, Y, Z coordinates relative to the world.
> - velocity relative to the world.
> - current raidus.
> - time until it becomes visible.
> - current density.
> - current illumination.
> 
> Unlike the smoke emitter, these properties will be completely isolated
> from
> the user.  In addition, it also needs several functions to:
> - calculate its new velocity.
> - calculate its velocity relative to the smoke source.
> - place itself at the new coordinate.
> - calculate its new radius.
> - change its own temperature.
> - change its own density.
> - change its own illumination.
> - determine what type of smoke it will be (explain later).
> 
> This way, the smoke can be create and forget.
> 
> As for the actual visible smoke, it can can takes on several geometries.
> A
> few useful ones are:
> - low poly sphereical.
> - cylindical (for smoke ring).
> - dougnut/torus (for a more detail smoke ring).
> - a simple polygon (for low velocity smoke).
> 
> Each type of geometry has its own advantages and performance issues.
> That's
> why it should be controlled by the smoke object instead of the user.  In
> the
> lifetime of the smoke, these geometries will expand, change orientation,
> and
> eveuntually deform, may even change type, and finally dissipate.
> 
> For the spitfire, since the smoke won't come out at very high speed during
> engine start, polygon should be used to represent each smoke object.
> 
> Now if only some kind soul will implement this. =P  To be honest, I would
> rather want someone to fix the framerate problem before working on eye
> candy.
> 
> Regards,
> Ampere
> 
> On July 22, 2004 11:06 am, Vivian Meazza wrote:
> > I've implemented a Coffman cartridge starter, and it would be nice to
> have
> > a cloud of black smoke come out of the exhaust and drift downwind at
> wind
> > speed before dispersing. I can do the first bit, but not the rest. I
> have
> > my eye on Fred's bump-mapped 3D clouds. Anyone any ideas on this one?
> > (Forget it could be good advice :-) ).
> 

Good analysis. How much of this already exists, either in the context of 3d
clouds or AI?

Regards,

Vivian



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