Re: [Flightgear-devel] Tides in FlightGear? From: Martin Spott - 2006-05-26 16:46 ```"Curtis L. Olson" wrote: > From a technical standpoint, how would you plan to "move" shoreline and > change all the underlying triangle structures in real time? The triangles don't have to be changed at all because in our Scenery the tidal area is part of the ocean. The idea was about changing nothing but the colour, Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -------------------------------------------------------------------------- ```

[Flightgear-devel] Tides in FlightGear? Martin Doege <mdoege@gm...>
 Re: [Flightgear-devel] Tides in FlightGear? From: Steve Hosgood - 2006-05-26 12:55 ```Martin Doege wrote: > Of course the tide calculations would not be required to be extremely=20 > accurate =E0 la xtide -- the hour angle of the Moon would probably be=20 > quite sufficient as a broad indication of tide. > It would have to be slightly more than just that. At the very least,=20 you'd need a delay-factor for the local hour-angle of the moon. Also an=20 amplitude-factor. Even then, you'd sometimes get the tide happening about an hour=20 displaced from reality due to the loss of the solar tide. If you added a=20 simple solar tide (i.e a delay factor for the local solar hour-angle and=20 a solar-tide amplitude-factor) then you'd probably be getting a pretty=20 good rough approximation for a given area. Good enough for a flight-sim,=20 certainly. It would also better model those areas of the world where the solar tide=20 dominates and there's only one significant tide per day. Steve ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Martin Doege - 2006-05-26 14:39 Attachments: Message as HTML ```> It would have to be slightly more than just that. At the very least, > you'd need a delay-factor for the local hour-angle of the moon. Also an > amplitude-factor. > > Even then, you'd sometimes get the tide happening about an hour > displaced from reality due to the loss of the solar tide. If you added a > simple solar tide (i.e a delay factor for the local solar hour-angle and > a solar-tide amplitude-factor) then you'd probably be getting a pretty > good rough approximation for a given area. Good enough for a flight-sim, > certainly. Yes, some kind of tide delay factor, preferably one that can vary from plac= e to place, as well as solar and lunar tidal amplitudes (from hour angle and distance) would probably be required to get something roughly accurate. However, calculating the tide for a given coordinate is probably the lesser problem here (one can use xtide's output for reference, etc.) My main issue is whether the visualization of the tidal effects can somehow be done with e.g. a Nasal script (good) or by extensively modifying the FG engine itself (not so good, since the FG/SimGear source code is pretty abstract and not very well-commented IMHO) It would also better model those areas of the world where the solar tide > dominates I thought the lunar tide is always dominant and the solar tide just adds to it during spring tide. Or have I misunderstood you there? Martin ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Curtis L. Olson - 2006-05-26 16:03 ```Martin Doege wrote: > However, calculating the tide for a given coordinate is probably the > lesser problem here (one can use xtide's output for reference, etc.) > My main issue is whether the visualization of the tidal effects can > somehow be done with e.g. a Nasal script (good) or by extensively > modifying the FG engine itself (not so good, since the FG/SimGear > source code is pretty abstract and not very well-commented IMHO) You would almost have to redo the scenery in the areas with ocean coverage to include the ocean floor elevation, then draw the ocean as a seperate layer that can be moved up and down exposing more or less of the terrain. The trick maybe to find a good sea floor elevation database that is reasonably compatible with SRTM, and mesh the two data sets seamlessly. Curt. -- Curtis Olson http://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text: 2f585eeea02e2c79d7b1d8c4963bae2d ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Martin Spott - 2006-05-26 16:30 ```"Curtis L. Olson" wrote: > The trick maybe to find a good sea floor elevation database that is > reasonably compatible with SRTM, and mesh the two data sets seamlessly. http://www.ngdc.noaa.gov/mgg/bathymetry/relief.html has an interesting survey on bathymetric data. But I don't think we need a realistic simulation of the effect for use in Flightgear, changing colours according to the tidal changes should be sufficient. This could be done by declaring respective areas of the ocean as tideland and moving the shoreline proportionally to the time that has passed since the last hig- or low-tides. Still someone would have to develop a schema to calculate the tides .... Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -------------------------------------------------------------------------- ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Curtis L. Olson - 2006-05-26 16:35 ```Martin Spott wrote: >"Curtis L. Olson" wrote: > > > >>The trick maybe to find a good sea floor elevation database that is >>reasonably compatible with SRTM, and mesh the two data sets seamlessly. >> >> > > http://www.ngdc.noaa.gov/mgg/bathymetry/relief.html > >has an interesting survey on bathymetric data. But I don't think we >need a realistic simulation of the effect for use in Flightgear, >changing colours according to the tidal changes should be sufficient. >This could be done by declaring respective areas of the ocean as >tideland and moving the shoreline proportionally to the time that has >passed since the last hig- or low-tides. >Still someone would have to develop a schema to calculate the tides .... > > From a technical standpoint, how would you plan to "move" shoreline and change all the underlying triangle structures in real time? Curt. -- Curtis Olson http://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text: 2f585eeea02e2c79d7b1d8c4963bae2d ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Martin Spott - 2006-05-26 16:46 ```"Curtis L. Olson" wrote: > From a technical standpoint, how would you plan to "move" shoreline and > change all the underlying triangle structures in real time? The triangles don't have to be changed at all because in our Scenery the tidal area is part of the ocean. The idea was about changing nothing but the colour, Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -------------------------------------------------------------------------- ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Curtis L. Olson - 2006-05-26 16:49 ```Martin Spott wrote: > The triangles don't have to be changed at all because in our Scenery > the tidal area is part of the ocean. The idea was about changing > nothing but the colour, > Ok, so you are only talking about areas that are marked explicitly as tidal areas in our land use/land cover data base, and then they would be either at full tide or no tide ... that's probably simpler to manage. Curt. ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Durk Talsma - 2006-05-26 16:56 ```Curtis L. Olson wrote: > Martin Spott wrote: >> The triangles don't have to be changed at all because in our Scenery >> the tidal area is part of the ocean. The idea was about changing >> nothing but the colour, >> > > Ok, so you are only talking about areas that are marked explicitly as > tidal areas in our land use/land cover data base, and then they would > be either at full tide or no tide ... that's probably simpler to manage. > > Curt. > I like the idea. Having some real-life experience flying over the "wadden" area that Martin (Doege) referred to, I can tell that the low tide areas can be very scenic. A change in texture would indeed suffice, because the elevation differences are almost negligable. Cheers, Durk ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Martin Doege - 2006-05-26 20:00 ```> Ok, so you are only talking about areas that are marked explicitly as > tidal areas in our land use/land cover data base, and then they would be > either at full tide or no tide ... that's probably simpler to manage. The idea was more like a linear transition between the high and low tide patterns. Only having the scenery flip-flop between two states is probably better than nothing at all but not perfect either (e.g., around Mont Saint Michel, the rising water has a horizonal speed of up to 1 m/s, so you can watch its movement easily!). If the low tide pattern is already marked in the land cover database as such, the only problem is calculating the horizontal shapes of the water as it rises (or falls). If the bathymetry is unknown, perhaps the horizontal patterns can be faked by using a 2D cellular automaton. The rules just have to set up so that the water rushes back into the narrower areas (where the water is supposedly deeper) first and when it falls, retreats from those areas last. The CA could be running in FG and occasionally update the sea / mud status of a randomly selected tile that is both close to the water and within the visible range. Martin ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Martin Spott - 2006-05-26 20:16 ```"Martin Doege" wrote: > If the low tide pattern is already marked in the land cover database > as such, [...] No, we currently don't have the low tide marks stored in the DB but I'm sure that we could retrieve it somewhere. For almost every area that features such a significant tidal phenomenon there's always some website which carries some photos or charts that we're allowed to use for digitizing. This task won't be done done in five minutes, some 'real' work is required, but it should not be _that_ difficult because we don't have to invent something totally new. Cheers, Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -------------------------------------------------------------------------- ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Arnt Karlsen - 2006-05-26 20:38 ```On Fri, 26 May 2006 20:16:14 +0000 (UTC), Martin wrote in message : > "Martin Doege" wrote: > > > If the low tide pattern is already marked in the land cover database > > as such, [...] > > No, we currently don't have the low tide marks stored in the DB but > I'm sure that we could retrieve it somewhere. For almost every area > that features such a significant tidal phenomenon there's always some > website which carries some photos or charts that we're allowed to use > for digitizing. > This task won't be done done in five minutes, some 'real' work is > required, but it should not be _that_ difficult because we don't have > to invent something totally new. ..you're thinking xtide and nautical maps? Only the latter would be needed for the tidal scenery builds, and xtide could be drawn into non-posix code builds like brlcad(.org) adds jove to have an emacs-like command editor. -- ..med vennlig hilsen = with Kind Regards from Arnt... ;o) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Ampere K. Hardraade - 2006-05-27 20:02 ```On Friday 26 May 2006 12:03, Curtis L. Olson wrote: > You would almost have to redo the scenery in the areas with ocean > coverage to include the ocean floor elevation, then draw the ocean as a > seperate layer that can be moved up and down exposing more or less of > the terrain. > > The trick maybe to find a good sea floor elevation database that is > reasonably compatible with SRTM, and mesh the two data sets seamlessly. > > Curt. I like this idea, as it is a more generic approach and could work for steeper shorelines (like those around KSFO). Smaller layers could then be used to simulate the effects of waves as well, and based on the camera's distance to these layers, we could then play the sounds for wave. Water surface should be handled differently than land right from the beginning. Right now, any plane could land on the water as if the water is a giant runway. By having the water as a separated mesh, we could finally simulate the plane-water interaction properly. I feel that this method would move us into the right direction. Ampere ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Detlef Faber - 2006-05-28 08:25 ```Am Samstag, den 27.05.2006, 16:14 -0400 schrieb Ampere K. Hardraade: > On Friday 26 May 2006 12:03, Curtis L. Olson wrote: > > You would almost have to redo the scenery in the areas with ocean > > coverage to include the ocean floor elevation, then draw the ocean as a > > seperate layer that can be moved up and down exposing more or less of > > the terrain. > > > > The trick maybe to find a good sea floor elevation database that is > > reasonably compatible with SRTM, and mesh the two data sets seamlessly. > > > > Curt. > > I like this idea, as it is a more generic approach and could work for steeper > shorelines (like those around KSFO). Smaller layers could then be used to > simulate the effects of waves as well, and based on the camera's distance to > these layers, we could then play the sounds for wave. > > Water surface should be handled differently than land right from the > beginning. Right now, any plane could land on the water as if the water is a > giant runway. By having the water as a separated mesh, we could finally > simulate the plane-water interaction properly. I feel that this method would > move us into the right direction. > > Ampere > that would be a chance for completing my albatros seaplane, imagine flying around those caribbean islands ... Greetings Detlef http://www.sol2500.net/flightgear > > ------------------------------------------------------- > All the advantages of Linux Managed Hosting--Without the Cost and Risk! > Fully trained technicians. The highest number of Red Hat certifications in > the hosting industry. Fanatical Support. Click to learn more > http://sel.as-us.falkag.net/sel?cmd=lnk&kid=107521&bid=248729&dat=121642 > _______________________________________________ > Flightgear-devel mailing list > Flightgear-devel@... > https://lists.sourceforge.net/lists/listinfo/flightgear-devel ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Martin Doege - 2006-05-28 12:43 ```> I like this idea, as it is a more generic approach and could work for ste= eper > shorelines (like those around KSFO). Smaller layers could then be used t= o > simulate the effects of waves as well, and based on the camera's distance= to > these layers, we could then play the sounds for wave. > >Water surface should be handled differently than land right from the > beginning. Right now, any plane could land on the water as if the water = is a > giant runway. By having the water as a separated mesh, we could finally > simulate the plane-water interaction properly. I feel that this method w= ould > move us into the right direction. And since one of the major selling points of "Flight Simulator X" will be, at least according to the screenshots and trailers, the more realistic depiction of water in all its pixel shader-rendered glory, it would be great if the water in FG would also be a little more than just the big blue parking lot it is right now. :-) Martin D. ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Steve Hosgood - 2006-05-30 08:58 ```Durk Talsma wrote: > Curtis L. Olson wrote: > >> Martin Spott wrote: >> >>> The triangles don't have to be changed at all because in our Scenery >>> the tidal area is part of the ocean. The idea was about changing >>> nothing but the colour, >>> >> >> >> Ok, so you are only talking about areas that are marked explicitly as >> tidal areas in our land use/land cover data base, and then they would >> be either at full tide or no tide ... that's probably simpler to manage. >> >> Curt. >> > I like the idea. Having some real-life experience flying over the > "wadden" area that Martin (Doege) referred to, I can tell that the low > tide areas can be very scenic. A change in texture would indeed > suffice, because the elevation differences are almost negligable. Basically, you could model a "tidal area" as a triangle mesh (as detailed as you like) where the triangle type is "tidal" and each triangle also carries a parameter "X" which is the local tide-height at which that triangle is covered by water. A tide-calculator finds local tide-height in a slow-running background loop, and every iteration of that loop, all triangles where X < tide-height are textured as "water", otherwise as "sand" (or mud). What's nice about that approach is that you can model tidal reaches with whatever detail you want. It could just be "tide in"/"tide out" as suggested by Curt (above) or vastly complex, handling the water flows of mudflats like the "wadden" area or Mont St. Michel. I've been interested in tides for years, and although 'Xtide' has now appeared (which outdoes my efforts), I've been offering a tide calculator program on my website for years: see http://tallyho.bc.nu/~steve/tides.html The underlying maths is very much simplified compared with Xtide, but would be fine for Flightgear. Help yourselves if you want it! Steve. ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Erik Hofman - 2006-05-30 09:07 ```>> Curtis L. Olson wrote: >> >>> Martin Spott wrote: >>> >>>> The triangles don't have to be changed at all because in our Scenery >>>> the tidal area is part of the ocean. The idea was about changing >>>> nothing but the colour, >>> >>> Ok, so you are only talking about areas that are marked explicitly as >>> tidal areas in our land use/land cover data base, and then they would >>> be either at full tide or no tide ... that's probably simpler to manage. Actually there is another method that caught my attention lately; 3d textures. By using a two layer 3d texture one could seamlessly blend between the layers based on a parameter that influences the texture z-parameter. Erik -- http://www.ehtw.info (Dutch) Future of Enschede Airport Twente http://www.ehofman.com/fgfs FlightGear Flight Simulator ```

 [Flightgear-devel] Sailing Ships (was Re: Tides in FlightGear?) From: Steve Hosgood - 2006-05-30 09:50 Attachments: Message as HTML ```Martin Doege wrote: >> By having the water as a separated mesh, we could finally >> simulate the plane-water interaction properly. I feel that this >> method would >> move us into the right direction. > > > And since one of the major selling points of "Flight Simulator X" will > be, at least according to the screenshots and trailers, the more > realistic depiction of water in all its pixel shader-rendered glory, > it would be great if the water in FG would also be a little more than > just the big blue parking lot it is right now. :-) > > Martin D. If there's an interest in improving FG's handling of water, might it be good to take in the idea that maybe one day the FG engine could be used for sailing ship simulation too? After all, FG's already got the 3D graphics engine, world scenery and a weather engine. Add in a sailing ship simulator "FDM", and a proper concept of water (tides, currents, depths, waves, 50-ft sea monsters etc) and you'd have it. Last year, I discovered Peter Davis's Tallship simulator "surprise.exe" and made a partial port to linux. Davis's website (for the original windoze program) is: http://home.wxs.nl/~pdavis My RPMs of the linux port are here: ftp://tallyho.bc.nu/pub/steve/surprise/surprise-20030924-2.i386.rpm My port is nowhere near complete in terms of options and eye-candy, but it does run. Mine only simulates the three-masted frigate (the original does that plus a two-masted brig). Mine doesn't have the "map" display nor any concept of land. The original modelled some "islands" to provide some entertainment trying to navigate. Mine doesn't yet show the "thrusts" diagram which tells you what forces are being provided by which sails. Mine doesn't yet have configurable weather, the original does. Porting it required me to tease out the "FDM" for Davis's ship simulator - it had been somewhat intertwined with the calls to the windoze API needed for his GUI. My version uses his "FDM" but with the GUI implemented with "Glade", the GTK+ GUI writer. I was actually using the project to teach myself Glade. Funnily enough, Peter Davis taught himself Visual Basic (and later Visual C) in order to write his ship-sim in the first place. His inexperience with computer programming does show in the code (along with its rather BASIC-like layout due to its heritage), but it does at least work. I've seen various people post queries about ship simulators on this list before, all to no avail. See here for a (commercial) 3D model of an 18th century frigate: http://www.turbosquid.com/FullPreview/Index.cfm/ID/240860/Action/FullPreview FG can't use this (obviously) but the FG project's got quite a few excellent 3D modeller experts in need of a challenge :-) If you get the "The Making of Hornblower" book that went with the UK's "Carlton TV" dramatisation of Forrester's books, then on the inner cover flysheets and the centre-spread there's a reproduction of a set of technical drawings for the "Grand Turk" (the ship used in the TV series, and used in the BBC's "Longitude" TV programme). To answer one obvious comment before it happens: yes, Peter Davis's source code (and my existing work on a linux port) are all GPL! I asked Davis last year if he would consider some sort of formal licence for his work, and he GPL-ed it last August. Steve ```

 Re: [Flightgear-devel] Sailing Ships (was Re: Tides in FlightGear?) From: Steve Hosgood - 2006-06-01 14:25 Attachments: Message as HTML ```Martin Doege wrote: > Hi Steve! > > Naval simulations are great, but if integrating tides into the > present-day ocean in FG is such a big technical challenge as it seems > to be, I would not think that a "real" ocean with rolling waves, > reefs, bathymetry, etc. is right around the corner. I think you would > want to have something like in Virtual Sailor or Silent Hunter III and > that is simply far removed from the blue plane that is currently the > sea in FG. > Hi Martin. I'm not sure the tides issue is likely to be a "big technical challenge" actually. In the space of about 4 postings here, a workable scheme was proposed of colouring certain triangles "sea" or "mud" according to their datum heights as compared with a local simplified tideheight generator. I can provide the maths for a tideheight generator, the only "problem" is providing a suitable set of triangles (tagged with datum heights) in a known tidal area. Also, on a tile-by-tile basis, a set of (probably four) tidal vectors has to be given. The graphics engine needs to know how to do the colouring on-the-fly, but compared with the magic that the 3D experts on this project have already acheived, that'll be done in an evening as soon as someone sets out to do it! > But in general naval simulations don't always need flashy graphics to > be fun, so finding a good graphics engine is probably not so important > at this point. I ws intimating that I don't have to find one - I've found it! Right here. :-) > As with all simulations, what really makes them absorbing is the > feeling of "being there", and while good graphics don't hurt, good > gameplay matters more. For example, the submarine sim Red Storm Rising > mostly had only tactical displays > > to look at that look about as boring as it gets, and yet it was an > engaging game and the suspension of disbelief worked well. > That's about what the current "surprise" program (windoze or linux) has. It's really just a wrapper around the "FDM" to let the "FDM" be used for something. > So instead of hoping for great seascapes from FG/SimGear in the near > (or not so near) future, I would first improve your existing "FDM", > add the ocean, include navigation aids, etc. Stars, sun and a stopwatch. That's all you get! Ok. Ok, I'm joking of course. That's all you get in the 18th century, but if sailing ships worm their way into the FG world, they'll be usable in any timeframe. After all, tall ships are still with us in the 21st century. > Cannons and a damage model should also be added since you are > mentioning Hornblower. > As in Sid Meier's Pirates!, the crew should also be simulated, [giant > snip] Funny, you've just written almost exactly what I wrote to "The Admiral" (Peter Davis) last year. His comments were that he never planned to make a game of the sim - his sentiments in fact matched closely to those we hear all the time here on the FlightGear discussions group. It's to be an accurate sim first and foremost, but if people want to add guns/missiles etc then that's up to them. I talked about crew, crew morale etc. (I've been a pen&paper RPG-er for a long time.) Same sort of response - basically, he (Davis) is only really interested in getting the sim to work well and would be disappointed to see the project "degenerate" into "just a game". Of course, done well then there's no reason why any of the additions you mention would degenerate the project - they should be seen as enhancements. > Graphics could initially be fairly minimal, perhaps isometric view or 2D. Dovetailing into FG would allow 3D models from the start. I really don't want to have to build a custom isometric or 2D graphics engine just for "surprise". > This would also give you time to develop a good interface. All your points are very valid - especially this one. Unlike aircraft, saling ships don't have a single "point of control". The nearest (in 18th century parlance) is "the quarterdeck" where the master or captain issues the orders, which then have to be relayed through several layers of middlemen to the grunts who pull the ropes. There is of course a "ship's wheel" but it's not a single point of control to compare with (say) an aircraft control column. Try it with "suprise". The ship's wheel does precious little unless the ship is moving at quite a lick. It's the set of the sails (especially the spanker) that really steers the thing. > I would also use a higher-level language for faster development and > improved flexibility. Python comes to mind and has the advantage that > the existing BASIC code should be easily converted to it and that > there is Libglade and pyGlade. It is also nicely modular and its sane > implementation of object orientation as well as its use of generators > are definite boons for simulations. At a later point, 3D graphics > could be added if desired, e.g. via PyOpenGL or using code in C/C++. > The existing code isn't BASIC, it's 'C' that looks like BASIC :-) As I stated before - Davis wrote the original in BASIC and ported it to 'C' many years later. I'm looking for volunteers, me hearties! First jobs involve completing the linux version to have all the features of the windoze original. Then there's the work involved in completing the segregation of GUI code from the "FDM". Then there's work in making the new sources compile on windoze to provide the same functionality it has now, but cleanly this time. Then there's the possibility of heaving the ship FDM into FlightGear, probably mis-using a "3D cockpit" idea to provide all the controls of rudder, yard-arms and sail-setting. Following that, a 3D model of the ship to make the "view out of the cockpit" look roughly like what you'd see over the rail of the quarterdeck. If this all gets left to me, it'll be 2018 at least before I'm anywhere near it! But with interested vounteers aboard, anything is possible. Tomorrow even. > PS. You might want to consider registering your Linux port of Surprise > at Freshmeat . > Currently, I consider it too incomplete. Also, the source code is an embarrassment! Source code is only available to people who sign a "non embarrassing disclosure" agreement :-) (Nahhh, not really. Anyway, it's GPL as you all well know. It's just *embarrassing* GPL, that's all.) Steve. ```

 Re: [Flightgear-devel] Sailing Ships (was Re: Tides in FlightGear?) From: GWMobile - 2006-06-01 16:23 ```What about changing the aerodynamic computation so they take place based=20 on radius from the earth and at what would be sea level change the air=20 density to that of water. Then any object below sealevel "flys under those equations. It would=20 allow for surface ships and submarines. And load in the whole terrain map of the world including all=20 bathespheric data The water surface could then just be a specialized cloud layer. That would give a great start. On Thu, 1 Jun 2006 10:30 am, Steve Hosgood wrote: > Martin Doege wrote: > >> Hi Steve! >> >> Naval simulations are great, but if integrating tides into the=20 >> present-day ocean in FG is such a big technical challenge as it seems=20 >> to be, I would not think that a "real" ocean with rolling waves,=20 >> reefs, bathymetry, etc. is right around the corner. I think you would=20 >> want to have something like in Virtual Sailor or Silent Hunter III and= =20 >> that is simply far removed from the blue plane that is currently the=20 >> sea in FG. > > Hi Martin. > > I'm not sure the tides issue is likely to be a "big technical=20 > challenge" actually. In the space of about 4 postings here, a workable=20 > scheme was proposed of colouring certain triangles "sea" or "mud"=20 > according to their datum heights as compared with a local simplified=20 > tideheight generator. > > I can provide the maths for a tideheight generator, the only "problem"=20 > is providing a suitable set of triangles (tagged with datum heights)=A0= =20 > in a known tidal area. Also, on a tile-by-tile basis, a set of=20 > (probably four) tidal vectors has to be given. > > The graphics engine needs to know how to do the colouring on-the-fly,=20 > but compared with the magic that the 3D experts on this project have=20 > already acheived, that'll be done in an evening as soon as someone sets= =20 > out to do it! > >> But in general naval simulations don't always need flashy graphics to=20 >> be fun, so finding a good graphics engine is probably not so important= =20 >> at this point. > > I ws intimating that I don't have to find one - I've found it! Right=20 > here. :-) > >> As with all simulations, what really makes them absorbing is the=20 >> feeling of "being there", and while good graphics don't hurt, good=20 >> gameplay matters more. For example, the submarine sim Red Storm Rising= =20 >> mostly had only tactical displays to look at that look about as boring= =20 >> as it gets, and yet it was an engaging game and the suspension of=20 >> disbelief worked well. > > That's about what the current "surprise" program (windoze or linux)=20 > has. It's really just a wrapper around the "FDM" to let the "FDM" be=20 > used for something. > >> So instead of hoping for great seascapes from FG/SimGear in the near=20 >> (or not so near) future, I would first improve your existing "FDM",=20 >> add the ocean, include navigation aids, etc. > > Stars, sun and a stopwatch. That's all you get! > Ok. Ok, I'm joking of course. That's all you get in the 18th century,=20 > but if sailing ships worm their way into the FG world, they'll be=20 > usable in any timeframe. After all, tall ships are still with us in the= =20 > 21st century. > >> Cannons and a damage model should also be added since you are=20 >> mentioning Hornblower. > >> As in Sid Meier's Pirates!, the crew should also be simulated, [giant=20 >> snip] > > Funny, you've just written almost exactly what I wrote to "The Admiral"= =20 > (Peter Davis) last year. His comments were that he never planned to=20 > make a game of the sim - his sentiments in fact matched closely to=20 > those we hear all the time here on the FlightGear discussions group.=20 > It's to be an accurate sim first and foremost, but if people want to=20 > add guns/missiles etc then that's up to them. > > I talked about crew, crew morale etc. (I've been a pen&paper RPG-er for= =20 > a long time.) Same sort of response - basically, he (Davis) is only=20 > really interested in getting the sim to work well and would be=20 > disappointed to see the project "degenerate" into "just a game". > > Of course, done well then there's no reason why any of the additions=20 > you mention would degenerate the project - they should be seen as=20 > enhancements. > >> Graphics could initially be fairly minimal, perhaps isometric view or=20 >> 2D. > > Dovetailing into FG would allow 3D models from the start. I really=20 > don't want to have to build a custom isometric or 2D graphics engine=20 > just for "surprise". > >> This would also give you time to develop a good interface. > > All your points are very valid - especially this one. Unlike aircraft,=20 > saling ships don't have a single "point of control". The nearest (in=20 > 18th century parlance) is "the quarterdeck" where the master or captain= =20 > issues the orders, which then have to be relayed through several layers= =20 > of middlemen to the grunts who pull the ropes. There is of course a=20 > "ship's wheel" but it's not a single point of control to compare with=20 > (say) an aircraft control column. > > Try it with "suprise". The ship's wheel does precious little unless the= =20 > ship is moving at quite a lick. It's the set of the sails (especially=20 > the spanker) that really steers the thing. > >> I would also use a higher-level language for faster development and=20 >> improved flexibility. Python comes to mind and has the advantage that=20 >> the existing BASIC code should be easily converted to it and that=20 >> there is Libglade and pyGlade. It is also nicely modular and its sane=20 >> implementation of object orientation as well as its use of generators=20 >> are definite boons for simulations. At a later point, 3D graphics=20 >> could be added if desired, e.g. via PyOpenGL or using code in C/C++. > > The existing code isn't BASIC, it's 'C' that looks like BASIC :-) > > As I stated before - Davis wrote the original in BASIC and ported it to= =20 > 'C' many years later. > > I'm looking for volunteers, me hearties! First jobs involve completing=20 > the linux version to have all the features of the windoze original.=20 > Then there's the work involved in completing the segregation of GUI=20 > code from the "FDM". Then there's work in making the new sources=20 > compile on windoze to provide the same functionality it has now, but=20 > cleanly this time. > > Then there's the possibility of heaving the ship FDM into FlightGear,=20 > probably mis-using a "3D cockpit" idea to provide all the controls of=20 > rudder, yard-arms and sail-setting. Following that, a 3D model of the=20 > ship to make the "view out of the cockpit" look roughly like what you'd > see over the rail of the quarterdeck. > > If this all gets left to me, it'll be 2018 at least before I'm anywhere= =20 > near it! But with interested vounteers aboard, anything is possible.=20 > Tomorrow even. > >> PS. You might want to consider registering your Linux port of Surprise= =20 >> at Freshmeat. > > Currently, I consider it too incomplete. Also, the source code is an=20 > embarrassment! > > Source code is only available to people who sign a "non embarrassing=20 > disclosure" agreement :-) > > (Nahhh, not really. Anyway, it's GPL as you all well know. It's just=20 > *embarrassing* GPL, that's all.) > Steve. Bush's family and Saudi partners make higher profits/prices by=20 preventing Saddam's huge Iraqi oil reserves from ever being sold.=20 They'll Enron the world - George Watson 2001 For Hurricanes http://www.globalboiling.com For solar wind and earthquakes http://www.electricquakes.com Typos caused by two inch mobile phone keyboard= ```

 Re: [Flightgear-devel] Sailing Ships (was Re: Tides in FlightGear?) From: Arnt Karlsen - 2006-06-01 22:25 ```On Thu, 1 Jun 2006 12:21:31 -0400, GWMobile wrote in message <1149178935.2E095058@...>: > The water surface could then just be a specialized cloud layer. ..in a way, it is. ;o) ..has anyone tried this idea by now? -- ..med vennlig hilsen = with Kind Regards from Arnt... ;o) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ```

 Re: [Flightgear-devel] Sailing Ships (was Re: Tides in FlightGear?) From: Steve Hosgood - 2006-06-02 08:49 ```GWMobile wrote: >What about changing the aerodynamic computation so they take place based >on radius from the earth and at what would be sea level change the air >density to that of water. >Then any object below sealevel "flys under those equations. It would >allow for surface ships and submarines. > >And load in the whole terrain map of the world including all >bathespheric data > > > I'd considered this, but I don't have the knowledge of hydraulics necessary to try and "parameterise" a ship's behaviour to suit (say) jsbsim. I think we'd need to spend some time running model hulls through water tanks or flumes if we were ever to gain that sort of data, and that means waiting until some Ph.D ship design students fancy getting into the project! I'm thinking more modestly for now, i.e take Peter Davis's "surprise" FDM as a starting point. It doesn't handle any of the flotation aspects of a ship - just assumes the ship is at water level (which is OK until you want to try handling behaviour in waves). Davis's sim basically deals with thrust on sails up masts at various heights with yardarms set at given angles. Oh, and a rudder of course. It does consider heeling though, and in a true "FDM" for a ship I believe a heeled-over hull (as long as it is moving) is a significant contribution to being able to steer the thing. I've not dug in deep enough to see if Davis deals with heeling effects using real data or just fudge-factors. Either way, I think it'll be OK for a starter. FG's world model doesn't even need bathymetric data to start with. Basically you could get away with "if (ship within 50m of land) then you've run aground;" as a starting point. Worry about bathymetrics *after* getting the rest of it to work. But you're right about submarines of course. They do fly in the water. Boats are the special case. Steve. ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Martin Doege - 2006-06-02 18:34 Attachments: Message as HTML ```> So I will try to convert this to SVG, maybe I can import it then. > The conversion worked, but the resulting 17 MB SVG file crashes Inkscape 0.42 on import despite the 1 GB of RAM. How crappy! Martin D. ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Martin Doege - 2006-06-02 19:16 Attachments: Message as HTML ```> Basically, you could model a "tidal area" as a triangle mesh (as > detailed as you like) where the triangle type is "tidal" and each > triangle also carries a parameter "X" which is the local tide-height at > which that triangle is covered by water. A tide-calculator finds local > tide-height in a slow-running background loop, and every iteration of > that loop, all triangles where X < tide-height are textured as "water", > otherwise as "sand" (or mud). > > What's nice about that approach is that you can model tidal reaches with > whatever detail you want. It could just be "tide in"/"tide out" as > suggested by Curt (above) or vastly complex, handling the water flows of > mudflats like the "wadden" area or Mont St. Michel. I have looked around for high-resolution Wadden Sea bathymetry on the Web and the best I have found yet is this map http://www.waddensea-secretariat.org/news/documents/WSP-Maps/MAP-CWSS-2003.pdf (CAUTION: huge PDF, low-res version here: http://www.waddensea-secretariat.org/news/documents/WSP-Maps/MAP-CWSS.jpg ). The problem is of course extracting the data back onto a grid to interpolate it. I suppose if I had Adobe Illustrator, I could simply import the PDF, delete everything that does not belong to the depth lines and export the image. Unfortunately, Inkscape cannot import PDFs as it seems. So I will try to convert this to SVG, maybe I can import it then. I have also sent an email to the Wadden Sea Secretariat asking if they can provide the gridded or raw data in a better format, but generally scientific raw data is a lot harder to come by in Europe than in the US, so my expectations are not very high. Martin ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Chris Metzler - 2006-06-03 03:06 Attachments: signature.asc ```On Fri, 2 Jun 2006 17:46:42 +0200 Martin Doege wrote: >=20 > The conversion worked, but the resulting 17 MB SVG file crashes Inkscape > 0.42 on import despite the 1 GB of RAM. How crappy! Is the crash really related to size? Maybe the SVG conversion was bugged? (of course, Inkscape should react to that better than by crashing, as well, but anyway.) -c --=20 Chris Metzler cmetzler@... (remove "snip-me." to email) "As a child I understood how to give; I have forgotten this grace since I have become civilized." - Chief Luther Standing Bear ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Ampere K. Hardraade - 2006-06-03 04:32 ```On Friday 02 June 2006 23:14, Chris Metzler wrote: > Is the crash really related to size? =A0Maybe the SVG conversion was > bugged? =A0(of course, Inkscape should react to that better than > by crashing, as well, but anyway.) > > -c If you have ever tried to convert complex PDF files into SVG format, then y= ou=20 would know that the resulting SVG file is very verbose. ;-) Ampere ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Chris Metzler - 2006-06-03 05:08 Attachments: signature.asc ```On Sat, 3 Jun 2006 00:45:33 -0400 Ampere K. Hardraade wrote: >On Friday 02 June 2006 23:14, Chris Metzler wrote: >> Is the crash really related to size? =A0Maybe the SVG conversion was >> bugged? =A0(of course, Inkscape should react to that better than >> by crashing, as well, but anyway.) >=20 > If you have ever tried to convert complex PDF files into SVG format, > then you would know that the resulting SVG file is very verbose. ;-) Oh, I have no doubt. But I'm all about filing bug reports when appropriate, and wanted to encourage doing so if that was the source of Inkscape's problem. -c --=20 Chris Metzler cmetzler@... (remove "snip-me." to email) "As a child I understood how to give; I have forgotten this grace since I have become civilized." - Chief Luther Standing Bear ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Martin Spott - 2006-06-03 12:57 ```"Martin Doege" wrote: > I have looked around for high-resolution Wadden Sea bathymetry on the Web > and the best I have found yet is this > map > http://www.waddensea-secretariat.org/news/documents/WSP-Maps/MAP-CWSS-2003.pdf [...] > The problem is of course extracting the data back onto a grid to interpolate > it. Wow !! the "Disclaimer" doesn't prevent us from using this document together with FlightGear or the Landcover-DB. We definitely should try to get this vector data into GRASS or some comparable system and separate the different layers - in case of doubt we even could use commercial software to do the required conversion. Once someone is able to load the data into GRASS, the geo-referencing should not pose any serious problem as lots of significant points have a well-known location. I'm looking forward to get hold of this data as I'm personally _very_ interested in this area .... Cheers, Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -------------------------------------------------------------------------- ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Arnt Karlsen - 2006-06-03 14:27 ```On Sat, 3 Jun 2006 12:57:05 +0000 (UTC), Martin wrote in message : > "Martin Doege" wrote: > > > I have looked around for high-resolution Wadden Sea bathymetry on > > the Web and the best I have found yet is this > > map > P-CWSS-2003.pdf> > > http://www.waddensea-secretariat.org/news/documents/WSP-Maps/MAP-CWSS-2003.pdf > [...] > > The problem is of course extracting the data back onto a grid to > > interpolate it. > > Wow !! the "Disclaimer" doesn't prevent us from using this document > together with FlightGear or the Landcover-DB. We definitely should try > to get this vector data into GRASS or some comparable system and > separate the different layers - in case of doubt we even could use > commercial software to do the required conversion. Once someone is > able to load the data into GRASS, the geo-referencing should not pose > any serious problem as lots of significant points have a well-known > location. I'm looking forward to get hold of this data as I'm > personally _very_ interested in this area .... ..Martin, see if you can find such data around GVAC (Cape Verde), looks like I have TerrorGear working in a few hours. Thanks to Fred B. for sending me a working gpc Makefile. :o) -- ..med vennlig hilsen = with Kind Regards from Arnt... ;o) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Martin Spott - 2006-06-03 17:00 ```Arnt Karlsen wrote: > ..Martin, see if you can find such data around GVAC (Cape Verde), > looks like I have TerrorGear working in a few hours. If you point me to a location where I can fetch such data I'll tell you if I managed to find it ;-) Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -------------------------------------------------------------------------- ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Arnt Karlsen - 2006-06-03 17:48 ```On Sat, 3 Jun 2006 16:59:45 +0000 (UTC), Martin wrote in message : > Arnt Karlsen wrote: > > > ..Martin, see if you can find such data around GVAC (Cape Verde), > > looks like I have TerrorGear working in a few hours. > > If you point me to a location where I can fetch such data I'll tell > you if I managed to find it ;-) ..pass, got a dead disk to try pry out TerrorGear from. Seriously, no big deal, just a few more hours. ;o) -- ..med vennlig hilsen = with Kind Regards from Arnt... ;o) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Martin Doege - 2006-06-03 18:05 Attachments: Message as HTML ```On 6/3/06, Chris Metzler wrote: Is the crash really related to size? Maybe the SVG conversion was > bugged? (of course, Inkscape should react to that better than > by crashing, as well, but anyway.) It looks like Inkscape needs to fit the whole image data into physical memory. It loads a little more of the file if I log into X without KDE, just some xterms, but it still crashes with a std::bad_alloc message when it has processed about 80%. I have slimmed down the SVG somewhat by removing the font definitions, bitmap images, text, and the red hatching with a text editor and grep. While the file is now "only" 13.5 MB in size, Inkscape still cannot load the whole thing. Maybe I should try to throw out more elements, based on their color? Or simply buy more RAM? :-) Martin D. ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Anders Gidenstam - 2006-06-03 18:23 ```On Sat, 3 Jun 2006, Martin Doege wrote: > It looks like Inkscape needs to fit the whole image data into physical > memory. It loads a little more of the file if I log into X without KDE, just > some xterms, but it still crashes with a std::bad_alloc message when it has > processed about 80%. [snip] > Maybe I should try to throw out more elements, based on their color? Or > simply buy more RAM? :-) If you have some spare disk space you could add more swap. I think that can be done using a swap-file so you don't even have to create another swap partition. See the man page for swapon(8) for more info. Cheers, Anders -- "In a world without fences, who needs gates?" Email: anders(at)gidenstam.org WWW: http://www.gidenstam.org/FlightGear/JSBSim-LTA/ ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Chris Metzler - 2006-06-03 18:50 Attachments: signature.asc ```On Sat, 3 Jun 2006 20:05:14 +0200 Martin Doege wrote: > > Maybe I should try to throw out more elements, based on their color? Or > simply buy more RAM? :-) Or file a bug. It sounds like you have plenty of RAM, so I wouldn't think this would be acceptable to the Inkscape folks. -c --=20 Chris Metzler cmetzler@... (remove "snip-me." to email) "As a child I understood how to give; I have forgotten this grace since I have become civilized." - Chief Luther Standing Bear ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Martin Doege - 2006-06-03 19:54 Attachments: Message as HTML ```On 6/3/06, Anders Gidenstam wrote: > > If you have some spare disk space you could add more swap. I think that > can be done using a swap-file so you don't even have to create another > swap partition. See the man page for swapon(8) for more info. Inkscape does not even seem to touch the existing 2 GB of swap, so adding more will help little. Memory usage just balloons to 750-800 MB, which is the physical memory minus memory used by KDE, X, etc., and then the app fails to allocate more. I always thought virtual memory was somehow transparent to applications, but in this case there seems to be a marked distinction between physical memory and swap space for some reason. Martin D. ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Martin Doege - 2006-06-03 23:07 Attachments: Message as HTML ```On 6/3/06, Martin Doege wrote: > > > Inkscape does not even seem to touch the existing 2 GB of swap, so adding > more will help little. Memory usage just balloons to 750-800 MB, which is > the physical memory minus memory used by KDE, X, etc., and then the app > fails to allocate more. > I just tried to open the file in Inkscape 0.43 under Mac OS X.... ....and it worked! Of course the poor little iBook is probably a little too slow to do much with the data after it has loaded, but at least the loading itself works nicely, even if it takes forever. I should try this on the other Mac tomorrow. So apparently Inkscape (or its developers) are not to blame here, it is the FreeBSD 6.0 virtual memory subsystem that seems to be a little wonky to say the least. I should have considered this possibility earlier, but apparently sometimes FreeBSD users are a little full of themselves and consider "production releases" of their OS of choice unsinkable. Which may have been true in the 4.x days, but not anymore, that much is certain! ;-) Martin D. ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Martin Spott - 2006-06-04 10:04 ```"Martin Doege" wrote: > So apparently Inkscape (or its developers) are not to blame here, it is the > FreeBSD 6.0 virtual memory subsystem that seems to be a little wonky to say > the least. Well, I'd be careful with such assumptions. You're correct in that FreeBSD-6.0 is not recommended for heavy-load production use (say FTP service with 3k simultaneous connections, I don't know if 'ftp.cdrom.com' still exists). Still you can assume that it eaily handles 1 GByte of RAM and more. My bet is that the port of Inkscape to FreeBSD probably "doesn't match the operating system close enough". My experience is that you often have to deal with Linuxisms in OpenSource software which probably show obscure behaviour on Unixes. Cheers, Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -------------------------------------------------------------------------- ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Martin Doege - 2006-06-04 12:19 Attachments: Message as HTML ```On 6/4/06, Martin Spott wrote: Still you can assume that it eaily handles 1 GByte of RAM and more. My > bet is that the port of Inkscape to FreeBSD probably "doesn't match the > operating system close enough". My experience is that you often have to > deal with Linuxisms in OpenSource software which probably show obscure > behaviour on Unixes. > I think Inkscape does its allocating via the C++ standard library function like any other application. So I see no reason to think that hidden Linuxisms are the underlying problem here. It looks like a FreeBSD issue to me because the failure occurs just as the physical memory is exhausted and the system starts to swap. And I believe the idea behind virtual memory is that the application does not have to know whether a page is in physical memory or swapped out. So the problem more than likely comes from the part of the system that "knows" what is happening, i.e. the virtual memory manager. But you are right, before filing a bug report, more tests with other memory-hungry apps would have to be conducted. And maybe this issue, if it exists in FreeBSD 6.0, is fixed in 6.1. However, I don't want to upgrade right now, as the system works well enough in all other regards. Martin D. ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Martin Doege - 2006-06-05 13:05 Attachments: Message as HTML ```> Well, I'd be careful with such assumptions. You're correct in that > FreeBSD-6.0 is not recommended for heavy-load production use (say FTP > service with 3k simultaneous connections, I don't know if > 'ftp.cdrom.com' still exists). > Still you can assume that it eaily handles 1 GByte of RAM and more. My > bet is that the port of Inkscape to FreeBSD probably "doesn't match the > operating system close enough". My experience is that you often have to > deal with Linuxisms in OpenSource software which probably show obscure > behaviour on Unixes. I just checked out the shell process limits and was shocked to find out datasize was limited to 1 GB. I vaguely recall I already had to up it from 512 MB to run FlightGear on FreeBSD a few months back. So I just increased the values in /boot/loader.conf even further: kern.maxdsiz="2048M" kern.dfldsiz="2048M" kern.maxssiz="256M" and, lo and behold, after a reboot the process limit is now at 2 GB and Inkscape can load the SVG, consuming a rather whopping 1266 MB of memory for a 12.9 MB image! Unfortunately, because Inkscape is swapping all the time, editing the SVG is still almost an impossibility, but at least in principle it works now. So I stand corrected: FreeBSD is a great operating system, it just has some pretty stupid defaults for people who want to use big data sets. :-) Martin ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Josh Babcock - 2006-06-06 03:03 ```Curtis L. Olson wrote: > Martin Doege wrote: > >> However, calculating the tide for a given coordinate is probably the >> lesser problem here (one can use xtide's output for reference, etc.) >> My main issue is whether the visualization of the tidal effects can >> somehow be done with e.g. a Nasal script (good) or by extensively >> modifying the FG engine itself (not so good, since the FG/SimGear >> source code is pretty abstract and not very well-commented IMHO) > > > > You would almost have to redo the scenery in the areas with ocean > coverage to include the ocean floor elevation, then draw the ocean as a > seperate layer that can be moved up and down exposing more or less of > the terrain. > > The trick maybe to find a good sea floor elevation database that is > reasonably compatible with SRTM, and mesh the two data sets seamlessly. > > Curt. > This would have a nice side effect of autmatically creating beaches. Josh ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Oliver - 2006-06-06 20:00 ```Am Sonntag, den 28.05.2006, 14:42 +0200 schrieb Martin Doege: > And since one of the major selling points of "Flight Simulator X" will > be, at least according to the screenshots and trailers, the more > realistic depiction of water in all its pixel shader-rendered glory, > it would be great if the water in FG would also be a little more than > just the big blue parking lot it is right now. :-) Maybe we could integrate code from the submarine simulation "Danger of the Deep". They have allready very nice eye candy water effects. Screenshots: http://dangerdeep.sourceforge.net/gallery.php http://dangerdeep.sourceforge.net/gallery/screenshot_0_1_1_01.jpg http://dangerdeep.sourceforge.net/gallery/screenshot_0_1_1_02.jpg http://dangerdeep.sourceforge.net/gallery/screenshot_0_1_1_03.jpg http://dangerdeep.sourceforge.net/gallery/screenshot_0_1_1_04.jpg It is an open source simulation like FlightGear and under the GPL license, so there shouldn't be a problem with code reuse from a license point of view. If we think about this a little further perhaps they might be interested in a merge of both projects. Because even a submarine simulation needs airplanes in the air and nice coast lines with hills and buildings on the land that is visible from the sea. :) Best Regards, Oliver C. ```

 Re: [Flightgear-devel] Tides in FlightGear? From: Oliver - 2006-06-06 20:10 ```Am Freitag, den 26.05.2006, 11:03 -0500 schrieb Curtis L. Olson: > Martin Doege wrote: > > > However, calculating the tide for a given coordinate is probably the > > lesser problem here (one can use xtide's output for reference, etc.) > > My main issue is whether the visualization of the tidal effects can > > somehow be done with e.g. a Nasal script (good) or by extensively > > modifying the FG engine itself (not so good, since the FG/SimGear > > source code is pretty abstract and not very well-commented IMHO) > > > You would almost have to redo the scenery in the areas with ocean > coverage to include the ocean floor elevation, then draw the ocean as a > seperate layer that can be moved up and down exposing more or less of > the terrain. > > The trick maybe to find a good sea floor elevation database that is > reasonably compatible with SRTM, and mesh the two data sets seamlessly. > > Curt What about using fake sea floor elevation data for the beginning when there is no real data available? Approaching it this way it should be possible to allready start with the implementation of the code and technical side of view. Real sea floor elevation data could then be integrated later, when we have found some good free sea elevation data. Best Regards, Oliver C. ```

 [Flightgear-devel] Sailing Ships and Submarines (was Re: Tides in FlightGear?) From: Steve Hosgood - 2006-06-07 11:31 ```Oliver wrote: >Maybe we could integrate code from the submarine simulation "Danger of >the Deep". They have allready very nice eye candy water effects. > >[...] > > >If we think about this a little further perhaps they might be interested >in a merge of both projects. Because even a submarine simulation needs >airplanes in the air and nice coast lines with hills and buildings on >the land that is visible from the sea. :) > > All of this applies to my earlier comments about tallships too. I'd not heard of Danger from the Deep before, it does indeed like a much better seascape simulator than FG currently offers. I suppose from FG's (and its users') POV, you have to ask is it worth having a better sea simulation? The argument for tides has been done, and is probably valid, plus it can be done with only a small change to the existing "flat blue parking lot" sea in FG. I suspect that another very small change to FG would stop ordinary aircraft landing on the water - it just becomes an automatic crash to come within a few metres of any body of water unless your landing gear includes floats. (Of course, FG currently doesn't have much of a concept of crashing...) Would incorporating a more realistic looking ocean contribute much to FG's flying experience considering it surely will reduce the achievable display frame rate? I can certainly understand the reverse idea - that DftD might like to adopt FG's world scenery to make its coastline approaches look more realistic (assuming they have a problem with that currently?). Steve. ```