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Author Topic: Smoke & Fire Effects, the structure of .eff files explained  (Read 8904 times)

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SAS~CirX

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This is still a bit half baked, but while gathering notes for the hier.him tutorial that is upcoming, I came across this note.

Some months ago I was messing around with some smoke mods, and thus, I crossed paths with the .eff type file.

I made this note, which is very incomplete. It starts off with some of the info on other sites and tutorials, but some of which is not accurate, and tries to adress it.

It is not complete, but I hope others here can add to it as time passes.

This is the basic layout, and the best , or collection of best ,old explanations of the .eff file

Quote
[ClassInfo]
ClassName TParticlesSystemParams
[General]
MatName Cannonsmoke.mat
Color0 0.64 0.66 0.68 1.0 // Start color (R B G A) 0 = Black 0.65 0.67 0.69 0.11

Color1 0.61 0.61 0.55 0.0 // End color (R B G A) 0.66 0.61 0.55 0.01

nParticles 300 // # of smoke particles 288

FinishTime -1.0 // How fast to draw 1st particle? , -1=draw continuously /Time before smoke starts to dissapear, begins to fade.

MaxR 1.0 // Max repeats? 1.0

PhiN 1.0 // Angular speed 1.0

PsiN 1.0 // Angular speed 1.0

LiveTime 6.0 // How long each smoke from conception to completion 4.0 How long the smoke will continue to come from the wings,
the start begins to fade.

EmitFrq 72.0 // Frequency emission, higher = more smoke

particles 48
EmitVelocity 0.5 4.0 // Min / Max speed of the emission 0.5 4.0

EmitTheta 90.0 0.0 // Min / Max angle of the emission 85 95

GasResist 0.01 // Resistance to expansion, lower = faster dispersal 0.05

VertAccel -0.6 // How fast to move up down vertically -0.6 if you want the smoke to rise "hence to gain altitude"

Wind 1.0 // wind is a random speed which moves particles

1.0 How Much Wind there will be when the smoke leaves the wings

Size 3.0 8.0 // Size of particles, start & ending size 2.0 8.0 The size the smoke will be

Rnd 0.30
   





So, some of that is not completely accurate, some is good and some is just off.

here is the last keynote I wrote for myself.


Quote
my defs

nParticles 4096 The number of particles assigned to a cycle
FinishTime -1.0
MaxR 0.0
PhiN 0.0
PsiN 0.0
LiveTime 4 length of the cycle
TranspTransitionTime 0.0f
EmitFrq 120 speed at which particles assigned is used up
SegmentLen 106

MaxObjectVelocity 150 I think this indicated how fast the smoke travels in the direction of the object that emmits it

EmitVelocity 2.0 5.0

EmitTheta 0.2 5.0

GasResist 0.05 How gradually it disperses, lower value fades away better, highr value stops abruptly. max value is 2/0 I think

VertAccel -0.0 this, and the wind setting, will make the smoke move after emmision. Vert accel seems to be how fats it rises..or falls

Wind 1.2


Size 1.0 2.0 Size at source and size when it starts dispersing

See this has two values. In this case the second is a bigger value, so the smoke will expand before it disperses, try this the other way round for fuel leaks or such.


Rnd 0.1

Unfortunately, I remember little of this, as I only looked into it very quickly.
But I hope this helps you when you next tangle with a .eff file.

What I can telll you is this:

Smoke works in a cycle, and the eff file basically adjusts

-how many partivcles will be used in a cycle
-how long that cycle will last before the next one begins
-how fast the particles you allow for each cycle is used up

...can you see tha math start to emerge in that?

The other important setting is gassresits, which basically means how hard will your smoke resist the urge to dissapear. This does not seem to have effect on when of how long the smoke dissapears, but just HOW it does. whether it fades away or just drops off a cliff sort off.

go figure the rest out, and let us know! I am not doing any smoke effects now, so I am not getting back to this in the near future, but I wanted to post what I had here, for the help of others

And then lastly, of course the eff file points to a mat file, which points to a texture.

Compare eff files of shells with smokes and see what you can learn


My explanations may be way off. I hope this gets you jump started though.

S!
CirX
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hguderian

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Re: Smoke & Fire Effects, the structure of .eff files explained
« Reply #1 on: September 01, 2009, 05:29:50 AM »

Hi! Do you may explain to me wich files rules the different guns smoke?
I'm usin the 3dSmokeTrail mod (I don't remember now the author) but only some AC guns seems to be affected by it.

If I would extend this mod to every AC gun...what file must be added?

Thanks in advance.
Best regards
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SAS~CirX

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Re: Smoke & Fire Effects, the structure of .eff files explained
« Reply #2 on: September 01, 2009, 05:45:44 AM »

dunno, but go to aaa and find the two mods called white curling gun smoke and grey curling gun smoke. (or somthing like that) bu Stuka_40, and look at their content and structure.
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hguderian

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Re: Smoke & Fire Effects, the structure of .eff files explained
« Reply #3 on: September 01, 2009, 06:48:25 AM »

Ok, thank you!
Cheers
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Sandman

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Re: Smoke & Fire Effects, the structure of .eff files explained
« Reply #4 on: September 03, 2009, 08:57:24 AM »



Hi all,

has anyone a list of the eff files that set the smokes parameters ?

The names of the files are somewhat confusing - so it would help a lot to know which files is doing which smoke . . .


Thanks in advance


Greetings from the Sandman
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billswagger

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Re: Smoke & Fire Effects, the structure of .eff files explained
« Reply #5 on: September 05, 2009, 09:02:16 AM »

 
The above information is useful for me to design my own smoke, but i was hoping to generate a smoke effect that also includes the flash when bullets or cannons connect with an aircraft.
So i'm thinking i can make the .eff but the game won't place the smoke unless i do what?

Bill
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Jonzynator

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Re: Smoke & Fire Effects, the structure of .eff files explained
« Reply #6 on: June 18, 2010, 04:49:45 PM »

R B G A Stands for Red Blue Green Alpha? Right
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santobr

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Re: Smoke & Fire Effects, the structure of .eff files explained
« Reply #7 on: June 18, 2010, 08:56:48 PM »

Bingo! ;D :P

0 to 1 = 0 to 255

 ;)

Cheers

santobr.
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billswagger

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Re: Smoke & Fire Effects, the structure of .eff files explained
« Reply #8 on: July 08, 2010, 05:15:24 AM »

I'm finding that using less particles in combination with the sizing and fading of the textures makes for a more FPS friendly effect.  I've managed to get very good and realistic results only using 5 to 20 particles on effects. Most smoke effects don't require more than 10.
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Eexhaton

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Re: Smoke & Fire Effects, the structure of .eff files explained
« Reply #9 on: September 25, 2010, 09:28:50 AM »

I'm very well aware of the functions of most .eff file entries, but this one still puzzles me:
Quote
TranspTransitionTime 0.0f

Has anyone any idea what it does exactly and what it's respective valid(!!) parameters are?

I have experimented with it, but changing only 1 digit resulted in IL2 loading errors.
E.g: TranspTransitionTime 0.0f  >to >> TranspTransitionTime 1.0f
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WxTech

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Re: Smoke & Fire Effects, the structure of .eff files explained
« Reply #10 on: May 02, 2015, 10:21:58 PM »

TranspTrsnsitionTime has me stumped, too. My feeling, based on the wording of the name, suggests that this might control the point at which the change in transparency commences. For instance, one might want a certain smoke to immediately begin to decrease in opacity, and another smoke to remain at the starting opacity for some set period and thereafter commence to decrease in opacity.


About GasResist. In my own extensive tweaking of smokes, I observe that this parameter controls the rate at which a smoke 'particle' is slowed down after being emitted. A large value (> 0.1) pretty quickly puts the brake on a particle. Very low values allow a particle to drift some distance before gradually coming to rest with respect to the surrounding air.

For example. Set this parameter to a large value for an engine fire, and the fire particles quickly slow down and trail far behind the plane, with individual particles spaced farther apart. Set it very low, and the fire particles mostly fly along with the plane, hardly slowing down, crowded closely together and making for a short trail.

Angles are in gradians (100 grads = 90 degrees)

Velocities are meters/second.

Frequencies are particles/second.

Acceleration is meter/second/second. 9.8 m/s^2 equals the gravitational acceleration (useful for particles blown off exploding vehicles, which will fall at realistic rates--if GasResist is not set very high; this will retard the rate of fall.)

PhiN and PsiN control the rate at which a particle spins about its own center, and rotates about the mean axis of travel defining its direction of emission. I forget offhand which is which. These are commonly used for smokes from ground sources, controlling the motion as the particles rise.

The unit of measure for PhiN and PsiN are rotation/revolution per its period of existence. For example, if set to 1, and the particle lasts 4 seconds, the particle will rotate/revolve once during that 4 seconds, which is a rate of 0.25 turns/second. If set to 0.5 for a 4 second live time, it will rotate/revolve 1/2 a turn in that 4 seconds, for a rate of 0.125 turns/second.

MaxR appears to control the maximum distance a particle deviates from the mean axis of motion. Not sure of the units; could be meters, but more testing is required to be sure. For example, for a ground smoke, with rising particles, the larger MaxR the wider the spiral a particle makes as it rises, which increases the 'twisting' aspect.


The foregoing are my own determinations based on fiddling with these variables when tweaking my own smoke effects.
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wellwill

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Re: Smoke & Fire Effects, the structure of .eff files explained
« Reply #11 on: September 19, 2015, 11:04:35 AM »

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