The Flying Water Spout

Show us your Realflow WIPs
shaun_michael
Posts: 4766
Joined: Sun Sep 10, 2006 8:04 am

The Flying Water Spout

Postby shaun_michael » Fri Feb 02, 2007 10:24 pm

Sorry Chris, I should have mentioned it. If you're looking to keep the "tube" of the particles the same diameter throughout, I would take out the radial force from your CPs. Do this by simply setting the radial force multiplier value (the one at the top of the spline daemon settings) to 0.0

Obviously zero multiplied by anything is zero so this will nullify all the radial settings you have in each CP thus not pulling the particles into the spline (which I guess is whats happening right now on your sim)

Should have mentioned that. The reason you're not seeing that in my screenshot is a) I forgot to change it back to liquid and run it again, and b) I'm a bit dim today :)

OK, give it a bash. It should work.

Good luck
Shaun


cpthomas
Posts: 30
Joined: Tue Jan 30, 2007 9:44 pm

The Flying Water Spout

Postby cpthomas » Sat Feb 03, 2007 12:50 am

Thanks for the tip!!

I set it up exactly like you have, but with liquid particles... and I get this:

http://walltowall.com/hawaii/3.jpg

It's the same issue that I was running into earlier. If I make my DSpline axial stronger, it will go way too fast and not become a stream -- just flying drops of water.

And when I ad the kSpeed, it doesn't seem to allow me to cut off the ones going too fast. It seems to affect the ones travelling too fast out of the emitter, but doesn't affect the ones that are speeding up because of the large axial values.

Any thoughts?

Chris

shaun_michael
Posts: 4766
Joined: Sun Sep 10, 2006 8:04 am

The Flying Water Spout

Postby shaun_michael » Sat Feb 03, 2007 12:14 pm

Hi Chris,

You seem to be having some proper bad luck there. I've run your sim for about 60 frames, at least up to the point where it's about to go through CP4.

I've zipped up the scene, minus bin files of course, here.

Have a look at the settings and run it, and let me know if the problem persists, as I notice you were on frame 100-odd. It does seem that your particles would have left the Dspline well before then. I changed rthe emitter to have a density of 1000 just to help speed things up in the sim.

Anyway, give it a go and let me know how it goes.

Shaun

shaun_michael
Posts: 4766
Joined: Sun Sep 10, 2006 8:04 am

The Flying Water Spout

Postby shaun_michael » Mon Feb 05, 2007 7:29 am

Hi Chris,

One thing occured to me while looking over your settings that I forgot to mention. I've noticed that you have your spline set to "Velocity". Heres's a quote from the water drop tutorial from NLs RF3 tutes linked in our tutorial section regarding that setting (the full duscussion can be read here under "Explanation: Force, Velocity, Acceleration, Momentum and Friction"):-

Now, if you switch the daemon to velocity mode, the daemon works on a different basis and the velocity gets changed with time in proportion to the strength value, without concern for the particle mass. It's important to be careful with this mode because it can lead very quickly to particles moving at high speeds. This is OK so long as the particles don't interact with anything, but when they do they then have large amounts of momentum.

and...

In general, the safest mode to use for daemons is force, because it causes more gradual, smooth changes in particle behaviour that are modulated through the particle mass. But don't forget about the velocity mode, it can be useful under certain conditions, like when you want more rapid changes.

This may well be worth noting. One of the problems with not running a sim to its conclusion (like I only ran a certain number of frames from yours), is that you can only really specualte on what's going to happen next. So, as I only simmed to a certain point, it is possible that things may go awry later, and this is one of the options to look at should this happen.

Cheers,
Shaun

cpthomas
Posts: 30
Joined: Tue Jan 30, 2007 9:44 pm

The Flying Water Spout

Postby cpthomas » Mon Feb 05, 2007 9:22 pm

Hi Shaun,

I downloaded the file that you sent, and rendered it past the 61 some frames that you had.

When I get to frame 73, I start to see this:

http://walltowall.com/hawaii/4.jpg

The particles are again flying off of the stream. I didn't edit the file in any way.. do you have any thoughts on this?

In the meantime, I'm working on a separate file using force instead of velocity.. but I can't get it to follow the CPs very well. And, if I put in a high axial value, they move way too fast. kSpeed doesn't slow them down, either, because it doesn't seem to affect the speed of the particles once they're being pulled by the axials -- just the speed out of the emitter.

Thanks for your continued help on this!! I know we'll get it... :)

Chris

shaun_michael
Posts: 4766
Joined: Sun Sep 10, 2006 8:04 am

The Flying Water Spout

Postby shaun_michael » Mon Feb 05, 2007 9:45 pm

I'm just running the first few frames of the sim up until they start to go through the first Control Point. I've set the Dspline to Force, rather than velocity, and I'm just watching the statistics panel for the emitter. Oh, and I've also taken the emitter and dspline out of the exclusive links node, as you dont really need then in there for this. The exclusive links node is for when you only want specific things to affect specific other things, without affecting everything else in the scene. As you also have the emitter and DSpline in the global links the exclusive link wouldn't work in this case any way - also, you dont need them in there as these are the only two elements in your scene.

OK, they've gone through CP 2, with an axial setting of 1000 in the multiplier section of the DSpline settings (not the individual CP axial settings), and they seem to be behaving ok (see attached pic). You can see from the stats [anel that the max speed of any particle in the scene is still 4 - which is what you had your emitter set to initially.

Have you got a screen grab of what they're doing that includes some settings for your DSpline please?

I'll have a look at them tomorrow.

Cheers,
Shaun

ps - you're right, we will get there :) If there's any software that one has to be patient with, its this one.

Attached files

cpthomas
Posts: 30
Joined: Tue Jan 30, 2007 9:44 pm

The Flying Water Spout

Postby cpthomas » Mon Feb 05, 2007 10:00 pm

Hi Shawn,

Here are screenshots of the particles with both the DSpline and the emitter information revealed:

http://walltowall.com/hawaii/5.jpg
http://walltowall.com/hawaii/6.jpg

Let me know what you think...

Thanks!
Chris

PS. I can't WAIT to really understand this software.. I'm so impressed with it (even with all of the problems I'm having!) and I'm excited to get good with it. :)

shaun_michael
Posts: 4766
Joined: Sun Sep 10, 2006 8:04 am

The Flying Water Spout

Postby shaun_michael » Tue Feb 06, 2007 5:37 am

Hi Chris,

Just about to leave for work, but enough time to post frame 120 of your set-up. Left it overnight and here's what I'm getting, plus the k_speed daemon settings. I'll have a look at your shots a little later.

I'm glad that you haven't given up, it'll be worth it in the end, and you'll be a Dspline expert to-boot.

Shaun

Attached files

shaun_michael
Posts: 4766
Joined: Sun Sep 10, 2006 8:04 am

The Flying Water Spout

Postby shaun_michael » Tue Feb 06, 2007 7:13 am

Hi Chris,

Just had a look at your screenshots.

Here's what I'd do:-

Change the DSpline main axial strength value (that's the one at the top of the list) 1000. This will multiply each of the control point's axial strength values by this number - so you'll have 1000x1.0 as a value, but the speed daemon will limit the speed to whatever you set it's max value to.

Add a speed daemon to the scene, and change the max speed to match the speed of your emitter. Turn "Limit and keep" to on.

Run a few frames and you'll see that the maximum speed of your particles will remain at the max set in the speed daemon.

Run the scene for as long as you like, and you should get pretty much exactly what I have in the screenshot above in the post above.

Cheers,
Shaun

cpthomas
Posts: 30
Joined: Tue Jan 30, 2007 9:44 pm

The Flying Water Spout

Postby cpthomas » Tue Feb 06, 2007 6:49 pm

Hi Shawn,

I'm trying it out now.. will let you know how it goes. :)

Chris


Return to “Work in progress”

Who is online

Users browsing this forum: No registered users and 1 guest