[captain_bazza]

Quote

Youtube is your obvious friend for videos.

101% spot on! :thumbup3:

Cheers Bazza

[rdamurphy]

Well, obviously then, I have my work cut out for me!

I have some work to do on the current code before I start making improvements, but I'll try to get something done this weekend that, hopefully, will be considered an improvement.

What is a good example of an MSTS steam locomotive that the smoke looks good on? Freeware, so I can have an example to work with?

Robert

[CrisGer]

right here in our own downloads, last pages of the Standard Steamers: the great Pierre Marquette engine:

cab view:
http://www.elvastowe...te-4-6-0-4-4-0/

Pere Marquette 4-6-0 & 4-4-0 by Huecuvoe

http://www.elvastowe...ette-149-4-6-0/

use my custom SMOKE ACE

we have a lot of great steamers here by master makers but this one has very nice physics and I have used it for testing my ACE development of that smoke.

Attached File(s)

•  CUSTOM SMOKE MAIN ACE.zip (984.97K)
  Number of downloads: 984

[_o_OOOO_oo-Kanawha]

These are the genuine N&W steam photos. Buried way too deep in my previous posting.
A lot of smoke on the excursion engines is just for taking good photographs.
Here is the real deal:
N&W steam in the 1950's by Bob Krone

Some of the nicest ones:
http://www.railpictures.net/images/d1/2/4/9/4249.1242333672.jpg
Towering exhaust from A Class 2-6-6-4
From the caption:
"An eastbound coal drag behind Y6 2129 and class A 1216 pull upgrade near the summit of the Blue Ridge grade. I met several other railfans on this trip and one of them must have been Jerry Carson as his movies of this exact train and scene are on Green Frog's " Steam In The 50's "
So that movie will show these trains in motion.
http://www.railpictures.net/images/d1/8/5/3/7853.1242332562.jpg
Towering exhause from Y class 2-8-8-2
http://www.railpictures.net/images/d1/5/3/6/8536.1237687489.jpg
J class 4-8-4 at speed showing very clean exhaust

[_o_OOOO_oo-Kanawha]

Thanks, Walter, my findings are exactly the same. OR doens't use that ace file at all, its smoke and steam effects are particle driven. Their are not sprites moving about as in MSTS.

On thinking over the particle stream that represents the exhaust I remembered my own experiments in the voodoo art of particle generation in Railworks.

I had two particle generators hidden in the smokestack. White steam, quantity controlled by throttle setting, and puffing in cadence with the wheels. Mix that emitter with another for grey to black smoke, quantity controlled by firing rate, colour by tractive effort. That way I got a reasonble representation of a working steam locomotive, even with the automatic fireman. So a light grayish white exhaust when coasting, thick billowing dark gray to almost black smoke when pulling heavily. Particle speed was not controllable, so the exhaust' didn't rise that much but drifted behing the engine nicely, slowly falling over the tender and train before dissolving so as not to have too many particles out. Some UK steam locomotives in Railworks even spew cinders and glowing particles.

Ideally, one should also be able to control the emitter's density, speed, "pressure" and volume of particles, and include back pressure reading in the equation. The particles should have mass, decay and dispersion parameters.

A tough one, I am inclined to think.

[D&RGW]

I really hope that the new steam effects for OR are particle driven, rather than moving sprites as Kanawha pointed out. The old sprite effects from MSTS are abhorrent--blocky and unrealistic regardless of the textures that are applied to them. The steam effects in Railworks, on the other hand, do manage to achieve a rather pleasant effect that doesn't detract from the experience. Best of all, they can be set up to synchronize with the driver rotation, meaning that a puff of smoke or steam is admitted every time one of the cylinders exhausts. Under the careful eyes of a programmer, I'm sure the particle effects in OR and Railworks could be fine-tuned to achieve a far more realistic behavior than could ever be possible with those godawful MSTS sprites.


Thanks,

Eliot

[rdamurphy]

The particle system doesn't use sprites, but rather quads. And it does use the smoke.ace, take a look at diesel exhaust, and if you watch, especially at idle, you can see them rotate.

Using two emitters is an interesting idea...

Robert

[James Ross]

 Walter Conklin, on 20 September 2013 - 01:46 PM, said:

Just curious: What causes the smoke and steam to appear differently in OR with various locomotives? Are all of the steam locomotives using the same steammain.ace?

All steam locomotives use the same steam texture (well, it comes from the installation profile [MSTS global folder] picked). What OR does differently to MSTS is that it applies a colour atop the texture, and the current implementation of this washes out a lot of the detail. Additionally, some locos in OR produce so many smoke particles/quads that the overlaid images are just a smudge of their former glory. The exact control on quantity comes from the steam physics and the nozzle size.

[CrisGer]

I noticed that too, some of the engines in OR do display some more realistic smoke, esp the AI ones. Strange. that flat balloon is the main one i have seen tho. And Railworks, the standard smoke is pretty poor, from my tests. If there are custom smoke effects for it i would love to see them but i was very disapointed in what i saw up to the latest release with that..so i am hopeful about OR :thumbup3: Great discussion, very interesting. I had no idea of the ACE would be useful or not, just wanted to toss it out there for helping if it could.

[rdamurphy]

Working on the equations today while I was at work, and I came up with the following:

Emission Rate <= Cylinder capacity maximum.

Emission Rate = steam volume / throttle percentage. (amount of steam in cylinder to be exhausted, based on the maximum steam that the cylinder will hold minus the amount of steam being admitted to the cylinder via throttle setting.

( pi * cylinder stroke * cylinderdiameter^2 ) * throttle percent + cuttoff percent / 2

Emission length = Wheel rps (determined by speed of locomotive )( RPS = 3600*S/(2*pi*R)) / number of cylinders * cutoff percent. i.e. length of time in seconds that one of the piston valves is open.

I'm going on two assumptions that I need verified: The throttle determines the volume of steam going into the open piston valve, and the cutoff determines how long the valve is open during the power and exhaust strokes.

Looking at this:

http://www.animatede...locomotive.html

It seems that the amount of steam admitted remains exactly the same at a given throttle setting? That seems confusing to me, because if the cutoff is closed, or nearly so, the steam isn't going into the cylinder, so then throttle percent * cutoff percent / 2 should be correct then? For the cylinder to receive steam equivalent to 100% of it's volume, both would have to be 100%. Closing the throttle to 50% would still only allow a maximum of 50% of steam volume, regardless if the cutoff is 100% open or not? This led me to conclude that the correct equation would be throttle percentage - ( 100% - cutoff percentage ).

So, if the throttle were at 50% full, and the cutoff was at 50%, half of the available steam from the throttle setting would go into the piston, which would allow half of the steam to pass through, meaning 25% is making it to the cylinder?

So, basically, the rate of steam particles will be dependent on the amount of steam going up the stack and will last as long as the piston valve is open on the exhaust stroke.

Next question is on stack smoke color.

Does the steam and smoke mix to the point that they blend in color? So, light smoke and heavy steam will be light grey, or do they really just exhaust from the stack separately? I watched several Youtube videos (great homework!) and it seems they sort of kind of stay separate?

Robert