[WIP] Improved Ship Physics

[aanker]

I was 'warned' about the scene.dat file, and it was suggested that it is too easy to mess this file up.

I wanted more distance with visuals. Having been on the Pacific deep sea fishing, I know I could see farther than what SH4 permits. That is either in scene.dat or hard-coded, I'm thinking mostly hard-coded.

Unfortunately, I know nah-sink.

Good plan you have then, to use Abilities to highlight/simulate early - late war GATO differences.

[TorpX]

I have been working on the scene.dat file, making changes to various values, and testing them. Mainly, I want to make the waves at the upper end of wind speed, larger, and more effective. Within limits, this is certainly possible.

Anyway, I have found a way to produce winds greater than 15 m/s, in missions. AFAIK, nobody has done this before. I don't know if it really has any practical value to the game, though. I have doubts as to whether the game would ever generate winds > 15 m/s, in career mode, or if this would mess up the weather in some way.

I will probably consider this a side project, and continue with a scene.dat scheme based on the usual top speed of 15 m/s, unless I can verify a version with a high top speed would work ok.

[Admiral Halsey]

You figured out a way to make the wind speed go faster then 15 m/s?

[aanker]

Maybe we can add Typhoon Cobra in Dec 1944 E Philippine sea - off Luzon, and place Admiral Halsey's Third fleet in the middle of it.

Nice breakthrough!

Happy Hunting!

[Admiral Halsey]

Originally Posted by aanker

Maybe we can add Typhoon Cobra in Dec 1944 E Philippine sea - off Luzon, and place Admiral Halsey's Third fleet in the middle of it.

Nice breakthrough!

Happy Hunting!

That would be something to see.

Edit. 1000nth post? WOOO!!!!!!!!!!!!!!!!

[Sniper297]

Dunno much about the Pacific since most of my flight hours and all my underway time was in the North Atlantic, but 15 meters per second works out to about 29 knots. It was a rare day in the Atlantic when we had LESS than that. The fixed wing AC of the day (F-4 Phantoms, F-8 Crusaders, A-6 Intruders, RA-5 Vigilantes) required a minimum of 30 knots down the flight deck for safe operation. Most of the time we just had to turn into the wind to launch or recover, very few occasions where we had to speed up to get 30 knots. 50 knots was probably closer to average with the ship doing only 10 knots, most times we actually slowed down for flight ops. YMMV, possibly the Pacific is "pacific" most of the time.

[TorpX]

Originally Posted by Admiral Halsey

You figured out a way to make the wind speed go faster then 15 m/s?

Yes, in a mission.

I noticed two things right off the bat. First the clouds were different. Instead of having heavy clouds with rain, like I originally put in the mission, I had fair weather clouds and rain (a concern). Second, the rain was almost horizontal; definitely different.

I don't know how the game generates weather, though. Does it use the location or season? Is it completely random? Would it ever produce winds above 15 m/s, in career mode?

For now, I don't want to get too caught up in the potential of higher winds. It could take some time to see if it has any real value.


PS - The reason why the waves don't look very high, is that they are only as high as we define them to be; meaning we can set waves to have certain characteristics at 15 m/s, or 30 m/s, or whatever. The waves pictured are what I had been using for 15 m/s.

[Admiral Halsey]

Originally Posted by TorpX

Yes, in a mission.

I noticed two things right off the bat. First the clouds were different. Instead of having heavy clouds with rain, like I originally put in the mission, I had fair weather clouds and rain (a concern). Second, the rain was almost horizontal; definitely different.

I don't know how the game generates weather, though. Does it use the location or season? Is it completely random? Would it ever produce winds above 15 m/s, in career mode?

For now, I don't want to get too caught up in the potential of higher winds. It could take some time to see if it has any real value.

I think it's somewhat dependent on season. I've noticed that in the fall months is when you're most likely to get a heavy rain.

[TorpX]

Originally Posted by Admiral Halsey

I think it's somewhat dependent on season. I've noticed that in the fall months is when you're most likely to get a heavy rain.

This would certainly make sense.

If someone knows of a particular file that has a bearing on this, it might be helpful.

[Hitman]

IIRC weather is dependant on season and latitude, there was a huge amount of research done on this for SH3 and SH4 still had a similar system with just some bugs fixed.

Regarding the visibility: In the first versions of SH4 you could easily modify the limit of visibility with a single parameter in the scene.dat, I remember having set 30 kms once. It caused some problems with the (not) curved horizon, though. For some reason, later patches changed that into a peculiar hardcoded system. Whereas in SH3 you can rescale the sky dome 3D for increased "world" around you, in SH4 scene.dat we find the old 8kms dome that is rescaled by the game engine to 20kms. Thus, increasing the dome size has no effect, the game will always rescale what it has inside to that distance.

Some other things to bear in mind: IIRC no units are "spawned" in a radius of 40 kms around your boat (If you stay that close to a habour where convoys or ships are programmed to spawn, they won't), nor is the 3D model effectively rendered if a unit is at outside that distance -meaning you would not see it anyway even if your world extends that far.

Please take all this with a grain of salt, I'm speaking out of my memory and might have forgotten lots of things. I'm just mentioning this so you can spare some research time and do yourself the tests to check wether what I said is valid or not.

Good luck

[TorpX]

Originally Posted by Hitman

IIRC weather is dependant on season and latitude, there was a huge amount of research done on this for SH3 and SH4 still had a similar system with just some bugs fixed.

Regarding the visibility: In the first versions of SH4 you could easily modify the limit of visibility with a single parameter in the scene.dat, I remember having set 30 kms once. It caused some problems with the (not) curved horizon, though. For some reason, later patches changed that into a peculiar hardcoded system. Whereas in SH3 you can rescale the sky dome 3D for increased "world" around you, in SH4 scene.dat we find the old 8kms dome that is rescaled by the game engine to 20kms. Thus, increasing the dome size has no effect, the game will always rescale what it has inside to that distance.

Ah, that explains why I didn't see anything in the file for the horizon limit; just for the sun, moon, and clouds. Too bad about that.

Thanks for the tip.

[TorpX]

I have been working on the ships for the next phase of ISP. Unfortunately, it looks like this will take more time than I thought.

I used cdp44's Ship Pack to test sim file values and get a few ships to accelerate and turn more realistically. I had hoped they would respond the same way in AI form. [The playable ships are built on altered submarine files, and obviously we need them to work in the game as ships.]

The immediate problem is that the Clemson DD sinks in heavy seas (15 m/s). I first tried adjusting the submerged depth in the sim file, but this did not help. Then I looked at the zon file and the 'CrashDepth'. It was at 300. This would seem to be more than enough. Nevertheless, I increased it to 1000, then 10000. Still the ship sinks.



BTW, I should mention that the ship does not slow down appreciably until it suffers damage. The waves may sink the ship, but they don't really add any drag. This seems rather perverse.

I presumed the figure is in meters, but maybe it is 'Martian meters, millimeters, or Tasmanian furlongs? The waves are not even close to 300 meters tall, so I really don't understand what's going on here.

After getting nowhere here, I zeroed out the crash speed, and this seemed to stop the sinking, but I am reluctant to do this.

Can anybody shed light on all this?

[TorpX]

I have been working intensely on the sea-keeping issue. I was able to craft reasonable sea-keeping qualities for the subs, so I thought I would be able to do the same for the ships. Unfortunately, this doesn't appear to be the case.

When I talk about 'sea-keeping', I mean ships being slowed significantly by large waves and heavy seas. In and of themselves, large waves do not appreciably slow ships in the game. This might surprise some, but it's true. I was able to give submarines realistic sea-keeping because they have a defined submerged speed and propulsion. This allows the game to calculate the drag effect of having the hull plunge deeper into the water. I'll elaborate on this point.

In SH4, there are two mechanisms whereby subs lose speed in heavy seas:

1. The boat pitches up and down. This in itself doesn't cause speed loss, but when the rear comes out of the water the screws will stop propelling the boat briefly.

2. The boat moves up and down, so the depth is going up and down. When the depth increases the game assesses extra drag on the hull. This is the same thing that occurs when you dive. It doesn't matter that you are not actually diving the boat; the drag starts as your depth increases.

The second mechanism produces the greater effect. However, this is absent with the surface ships. They have no defined submerged speed/propulsion, and there is no increased drag in heavy seas. The ships will lose a little, due to the screws coming out of the water, but this amounts to a lost of only about 0.2 to 0.4 kt. at 10 kt. This is hardly significant. At higher speeds it gets worse. The faster the ship moves through the waves, the less effect they have on it.



I tried using S3d to build a different version of a sim file and found a difference in what S3d produced from the in-game versions:

The unit_Ship chunk was added by S3d and has 2 FR drag elements in the file that aren't in the game files. This was very exciting to me as it seemed to offer a solution to increasing the drag like I wanted to do. The FR stands for front-rear. Alas, it doesn't seem to actually do anything. After trying many values, big, small and in-between, I can't find any change in the results.

Perhaps someone can shed some light on this. Does anyone know if this quantity was used in SH3.

For now, I have put this aside, and gone back to working on things that I can fix.

[TorpX]

ISP work

I have finished with the ships and for the most part the subs are ok. I made an attempt to improve the diving characteristics, but I decided they are as good as I can make them already. Tweaking the various drag factors just caused problems.

I expect to release a version for RFB + RSRDC that will have all the subs and ships in one package. I doubt that I will build a separated RFB only version. I could, but I doubt there would be much demand for this. I think most who use RFB also use RSRDC.

I wanted to include files for the Narwhal class, but found that the Narwhal just doesn't work right in RFB. RFB 2.0 has only an empty folder for the Narwhal, RSRDC has it's version of the Narwhal, but it doesn't work right. I presume it worked ok with an earlier version of RFB.

If someone knows how to straighten these issues out, I'll take a stab at fixing them, otherwise I'll release ISP 2.0 without any Narwhal support.

I can get crew into the empty slots of the control room and fwd torpedo room, but don't know how to do this for the deck watch. The 3 men in the Hogan's Alley did not appear there, but were in the roster, at left, and didn't show up on the boat until I moved them there. Worse yet, the control room and sonar stations are messed up; when you try to go there, you end up outside the boat. In short the Narwhal is unusable, as it is, and I have no idea how to fix this.

[merc4ulfate]

I have seen horizontal rain in real life in the Navy .... looked cool. The sea was totally calm during it too.