LOS, LOF, units, and you!

[Cameroon]

Originally posted by undead reindeer cavalry:

with tanks, it's usually too tempting to put tanks one after another in good keyhole positions, instead of side by side, because you can fire thru friendly tanks. i hate doing it, because it simply could never be done in real world, and to lesser part because it takes away many reasons for real world tank tactics.

I'm fairly sure that the changes to LOF as described already take care of that issue. You can't fire through a vehicle that is blocking LOF, but a vehicle could move through the path of the round at some point.

I tend to agree with your comment on making in-flight checks for large-bore weapons and not small arms. There aren't many large-bore weapons on the map and their rate of fire is low, so tracking each round would seem feasible on an "as often as possible" basis.

[Tero]

Originally posted by Cameroon:

</font><blockquote>quote:</font><hr />Originally posted by undead reindeer cavalry:

with tanks, it's usually too tempting to put tanks one after another in good keyhole positions, instead of side by side, because you can fire thru friendly tanks. i hate doing it, because it simply could never be done in real world, and to lesser part because it takes away many reasons for real world tank tactics.

I'm fairly sure that the changes to LOF as described already take care of that issue. You can't fire through a vehicle that is blocking LOF, but a vehicle could move through the path of the round at some point.

I tend to agree with your comment on making in-flight checks for large-bore weapons and not small arms. There aren't many large-bore weapons on the map and their rate of fire is low, so tracking each round would seem feasible on an "as often as possible" basis. </font>

[John D Salt]

Originally posted by Battlefront.com:

[snips]

This LOS checking is an extremely hardware intensive thing to do. The more units you have, the more terrain to scan, the more variables to consider... the worse it is. Then there is the frequency issue... in theory a unit is usually scanning around itself constantly without interruption. EVERY unit. On BOTH sides.

This is another good reason to change the suppression model in CM to suppress infantry early, and suppress them hard. When a unit is heads-down in cover, it doesn't need to make any LOS checks, it can't see a dam' thing.

Likewise, closed-down tanks in CM at the moment can IMHO see far too much, but I'm not sure how reducing their vision can be used to prune the number of LOS checks to be made -- is there a quick way of retrieving all the potential targets that lie within a fan-shaped area? I seem to remember something about pretty fast a "right-of" operator one can use with Plücker co-ordinates.

All the best,

John.

[c3k]

Gents,

A LARGE consideration: LOS/LOF seem to be merging here. The difference between them only being if a target can be affected. I disagree. There are plenty of INDIRECT fire weapons which utilize a highly arced trajectory specifically to fire against targets with which there is no LOS. And I'm not talking about on-call assets.

Here are some examples: M-79 grenade launcher; M-203; light mortars; short-barrelled infantry cannon (German 7.5cm, 15.0cm); trebuchets; rifled muskets; bombards; and all the rest in this category.

This category of weapon is NOT displaced away from the firing line. They are right up front, and they can see what they want to hit, yet they cannot see their target. "Sergeant, drop HE directly behind that house!" You can see the house; you saw a target move BEHIND the house; you have a weapon which can arc rounds OVER the house; you have NO LOS there, yet, you CAN fire at it.

Will CMx2 support fire by units where the is NO LOS?

Thank you,

Ken

[aka_tom_w]

Originally posted by Cpl Steiner:

In theory it could take a bit longer when it generates the action phase, but even then I concede that there are limits on how long the player can reasonably be expected to wait.

AND this should be talking about A LOT MORE!

How long is the player willing to wait????

If you want a REALLY big battle with lots of units you have to wait longer for the crunch.

If you have a slower computer you have to WAIT longer for the crunch

if you want TRUE LOS and LOF collision detection you have to wait longer for the crunch

Steve did not talk about balancing in the wait time.

Given enough time and money you can have almost anything you want.

Given enough wait time on the crunch I would guess even the very highest fidelity of collision detection would be possible, (any computer can do it, it just takes longer NO??)

Wait time for the crunch should be mentioned in the balancing act Steve is talking about.

-tom w

[Sergei]

Originally posted by c3k:

This category of weapon is NOT displaced away from the firing line. They are right up front, and they can see what they want to hit, yet they cannot see their target. "Sergeant, drop HE directly behind that house!" You can see the house; you saw a target move BEHIND the house; you have a weapon which can arc rounds OVER the house; you have NO LOS there, yet, you CAN fire at it.

You can fire at it; yet I challenge the effectiveness of such fire. For indirect fire to be accurate, one must be able to see the impact point. In your example, you can see the rounds arc over the obstacle - but how far??? No idea. It might very easily go 100m too far and you would never know.

Also, I question your list of weapons which could be used for this kind of firing. I doubt it would be practical with infantry guns.

[Michael Dorosh]

Originally posted by c3k:

Here are some examples: M-79 grenade launcher; M-203; light mortars; short-barrelled infantry cannon (German 7.5cm, 15.0cm); trebuchets; rifled muskets; bombards; and all the rest in this category.

Thank you,

Ken

PIAT was also used as a mortar late in the war, and fired indirectly, or at least semi-indirectly

http://www.calgaryhighlanders.com/history/queslyster.htm

PIAT Can be fired at high angle - very useful for house clearing - has good range 300 yards - 400 yards

[ September 06, 2005, 11:13 AM: Message edited by: Michael Dorosh ]

[Battlefront.com]

Various different issues here. First, the examples Metto:

This thing, that moving objects(tanks etc.) only tell the units "you must not fire here", creates an exploit.

Situation 1: A tank is advancing towards a machinegun and has infantry following it, "in cover". The player controlling the machinegun gives it an area fire order ahead of the tank -> when the tank and infantry moves forward, the mg keeps shooting the spot and hits the infantry through the tank.

Situation 2: There's a light infantry gun instead of the machinegun, and the tank is a heavy tank, so the gun can't kill it. The tank is sitting in level terrain, so even a small adjustment in the guns elevation may result in the gun's rounds going very short or very far from the tank. The player sets the gun to fire in front of the tank and when the gun eventually misses above it's ground target, the shell flies through the tank and hurts the infantry.

Niether of these are valid. If the tank is there when the shot is fired, then it will block the shot because LOF is calculated each time the unit goes to shoot. Simple as that.

Firing indirectly, as some of you are talking about, has nothing to do with this discussion. It is an entirely different discussion.

All my statements about what we can/can't do took into consideration the ability to crunch numbers "off line". My answers therefore remain unchanged.

It might be possible to do a special LOFcheck for heavy stuff, but I doubt it. It isn't like this adds a wee bit to each heavy shot fired... it adds a TON of checks. How often do you need to check? Well, for a shot traveling 2000m you'd need it to check a heck of a lot. In theory, every meter since that is what the grid is setup for. That means 2000 extra LOF checks. Not all the same, granted, because each successive check is shorter than the last one. But I've seen tank battles with a dozen tanks firing at let's say 2 times each at 1000 meters. This means 24000 LOF checks have to be done JUST for those tanks. The way it works now is we only would do 24 LOF checks. OK, don't like that example... fine... 6 tanks at 1000 meters firing 2 rounds each... 12000 LOF checks vs 12 LOF checks we do now. How much of an impact will this have on the resolution speed? Obviously quite a lot. And we also have to plan on having at least a dozen tanks slugging it out at any given time, even more in fact.

Guys... please... do us a big favor... don't try to get into Charles' jar and second guess how to code something like this. It never has, and never will, come to any good. Instead, just accept the fact that he knows what he is doing and the best possible result will come of this reality.

Steve

[c3k]

Sergei,

As for WWII German infantry guns, I refer to Knappe(?), who started as a battery commander. In the opening stages of the campaign against the Soviet Union, in his autobiography he specifically states how useful his 7.5cm cannon were against targets hidden from straight-line fire.

Steve - thank you.

Regards,

Ken

[aka_tom_w]

It might be possible to do a special LOF check for heavy stuff, but I doubt it. It isn't like this adds a wee bit to each heavy shot fired... it adds a TON of checks.

-Steve

Thanks Steve

I think that is what most of us are concerned about "the heavy stuff".

and the potential for "gamey" exploitaion of the system if that is possible.

I was thinking the discussion might also include some idea of the length of "wait time" on the crunch "the general gaming public" would endure. We know the grogs amongst would prefer the more accurate and longer wait time for the crunch if all collision detections of all heavy (tank to tank or anti tank) rounds could be tracked. BUT how long with the crunch really be

a few extra minutes or are we talking about hours? or the reality of a 30-45 min crunch time for ONE TURN.??

Who knows?

I don't have any clue.

My only experience with the Long crunch time was that MASSIVE CMBB Volga monstrosity that took FOREVER to crunch. So guess what??? I never played that scenario.

You KNOW what we REALLY want is the OPTION to turn on "High Fidelity Collision Detection" (for the Heavy stuff ) in the fog of war settings with a warning that it would doube or triple or quadruple the wait time on the crunch.

(I know I know ... "Don't expect it in the first game engine!" )

thanks

-tom w

[ September 06, 2005, 09:25 AM: Message edited by: aka_tom_w ]

[Sergei]

Originally posted by c3k:

Sergei,

As for WWII German infantry guns, I refer to Knappe(?), who started as a battery commander. In the opening stages of the campaign against the Soviet Union, in his autobiography he specifically states how useful his 7.5cm cannon were against targets hidden from straight-line fire.

What were the ranges for that?

[YankeeDog]

Can't say for the 7.5 cm, but we just had a discussion about high-angle fire from the 150mm SiG on another thread.

Max elevation for the 150mm was 75 degrees; only 5-10 degrees short of the max elevation of most mortars.

No one could find a documented number on minimum range, but JonS, I think, did a quick estimate using 75 degrees and min. charge (122 m/s mV) works out to somewhere around 100m.

Max. Range was 4700m for the weapon. So given the multiple charge settings available, you'd expect the 1500mm SiG to be able to do high-angle (>60 degree angle of descent) in a range from 100m out to at least 2km or so, very applicable to the typical CM-sized map.

[c3k]

Sergei,

The ranges Knappe(? - it may not have been him, and I haven't bothered to double check) talked about were easily within a couple hundred yards. It could've been closer. This is all from memory. It sticks out, though, because I'd never thought that these weapons could be used in a manner similar to mortars, especially at very short range.

Yankee Dog - thank you.

Regards,

Ken

[Andreas]

Originally posted by c3k:

Sergei,

As for WWII German infantry guns, I refer to Knappe(?), who started as a battery commander. In the opening stages of the campaign against the Soviet Union, in his autobiography he specifically states how useful his 7.5cm cannon were against targets hidden from straight-line fire.

Steve - thank you.

Regards,

Ken

Without observation?

Both IGs had six different charges.

[kipanderson]

Hi,

All sounds good to me.. Boring answer, but true

This is not an issue that has ever truly excited me, but no longer being able to cram a platoon of tanks down a narrow road and have them “all” engage “any” enemy target is great. That is the bit that really matters.

The only factor that finally got the better of me in CMX1, i.e. in the end hit my enjoyment, is Absolute Spotting. As this is now dead, replaced by Relative Spotting, I am a happy chap .

All the best,

Kip.

[Sergei]

Originally posted by kipanderson:

Hi,

All sounds good to me.. Boring answer, but true

This is not an issue that has ever truly excited me, but no longer being able to cram a platoon of tanks down a narrow road and have them “all” engage “any” enemy target is great. That is the bit that really matters.

Yep. Of course, it comes at a cost - how many of you think the AI will be capable of utilizing this feature?

But regardless, realistic tank tactics are a lot harder than CMx1 makes them look. The dust in CMAK was just a teeny weeny taster of this.

[c3k]

Andreas,

The observation was accomplished by standing a few yards away from the guns and watching where the rounds impacted. Dirt, dust, and smoke rising from behind the house? Good. Walk them closer. Hit the roof? Ooops. Further back a bit. So, in that sense it was observed.

Thanks,

Ken

[Andreas]

Thanks. I think that would be equivalent to allowing area fire in a short distance from the last LOS point?

[Drusus]

Few things:

1. I think that when people are saying that FPS games need to do the checks realtime I think they miss one important point: If CM does the checks in realtime it means that the computing of the turn will take 1 minute. Are you sure that average customer is ready to wait 1 minute? Ofcourse there are a lot of other stuff that fps games do in realtime but also, there are a lot more units to check in CM.

Also, there is this thing that if ram is the limiting factor, then adding more time doesn't help. This is because when you go to swap, everything becomes _really_ slow. I was teached that if you look something up from the processor cache, it is like getting something from fridge. If you use ram, it is like going to shop. If you use swap, it is like going to moon.

Now, there are 60 units maximum in FPS games. Lets assume that every unit takes 4 units of ram for the LOS checking. Now, the used ram is 60x4= 240 = maximum acceptable ram usage. Now, assume that in CM it takes 1 unit of ram for every unit. Now the amount is 200x1=200 -> OK! But if every check takes 4 units of ram you will use 800 units. This is WAY over the limit. Now you will be badly swapped, and this means unnacceptable performance. I assumed that the amount of checks is doubled if the amount of units is doubled. It is very well possible that this is wrong. But if it is wrong, the amount of checks in CM will be higher, not lower.

2. I don't know much about coding, but there is one point Id like to ask. Smoke cuts LOS in CM. How is this done? Is the LOS map recalculated every time when smoke goes "on" and "off"?

[pamak1970]

Originally posted by YankeeDog:

Can't say for the 7.5 cm, but we just had a discussion about high-angle fire from the 150mm SiG on another thread.

Max elevation for the 150mm was 75 degrees; only 5-10 degrees short of the max elevation of most mortars.

No one could find a documented number on minimum range, but JonS, I think, did a quick estimate using 75 degrees and min. charge (122 m/s mV) works out to somewhere around 100m.

Max. Range was 4700m for the weapon. So given the multiple charge settings available, you'd expect the 1500mm SiG to be able to do high-angle (>60 degree angle of descent) in a range from 100m out to at least 2km or so, very applicable to the typical CM-sized map.

Yankeedog , i do not want to highjack this thread which is really important.

I will just point that the minimum range does not seem to match with the numbers you use to calculate it.

It is way too short.

I can send you an email with more details if you are interested

[flamingknives]

I make it 420m minimum range at 75° for a 29kg shell, m.v. 122m/s and a Cd of 0.235.

I've got a ballistic calculation table here

You'll need to wade through the values a bit to alter things though.

[YankeeDog]

Well, that's what I get for relaying on someone else's calculation!

Next time, I'll do my own math. . .

A few quick calcs of my own fall in the 400m ballpark for minimum.

[flamingknives]

I like subsonic trajectories - they're easy.

Transonics are a bit of an arse though.

[pamak1970]

Originally posted by flamingknives:

I like subsonic trajectories - they're easy.

Transonics are a bit of an arse though.

Two questions.

Did you find data regarding the particular weapon ,like Cd and weight of shell , or you just tried to calculate roughly the magnitude of the minimum range ?

The second question is if you are aware of a program for transonic ballistics.

Thanks

[pamak1970]

I mean transonic-supersonic ballistics