View Full Version : a boat and a piece of cloth

03 March 2006, 05:32 AM
I know this is starting to become redundant, but my question really isn't the same. I have an animation of a "boat" moving through some "water" and the hull needs to interact with the water with - ta-da - via clothe fx. Now if was to take a base setup like eki's seagen where it makes a phenominal mesh for the ocean (which is good), but i'm thinking that just in calculation time it would be most disapointing. SO, I'm looking for answers on how do I create the effect that I want, keep calculation times down, and make the whole ocean work as one. BTW, I've noticed that when you apply a displacement texture and animate it to an object that you wish to behave like water, it falls to the wayside. Any ideas on that as well?

IF was to do this in stages, what would be the best way to do it? The trouble is that I have a distant shot coming in, then a beauty shot that will last about 10 seconds or so.

03 March 2006, 06:10 PM
Is this ( the kind of thing you mean, this was done with a collision null instead of using the hull as a collision object(to save calculation times), if you run clothFX on your water switch off the displacement, and fix any points that you think will be outside the motion of the boat.Once you have the motion saved you can play it with local playback and then enable the displacement and you will get the two motions blended.
As to the motion of the displacement texture why not put an oscillator motion modifier on its position

03 March 2006, 07:05 PM
Yes, that is exactly what I'm trying to achieve. Do you have a sample scene of your setup?

BTW, is the ocean split up into 2 different parts? One for calculations, the other just in thebackground?

03 March 2006, 11:27 PM
I have attached a test scene for you but it will need calculated, to do this goto the water/properties/deform and switch off texture displacement, then calculate the dynamics and save the file, once saved set the playback mode to local and re-enable the texture displacement.
The water object could be cloned and used to build an ocean(dropping the subD level as you get away from the camera) or if you need to use one large water object make a weight map to fix the points not influenced by the wake (check the calculation time difference if you fix/none in the object supplied)

good luck and lets see the results

03 March 2006, 11:31 PM
cool stuff Lightfreeze! :D you know Im always up for ClothFX :D, but this can also be done with displacements, nulls, alphas and no plugins (except particles of course) like this Ocean I made on my reel at (

if youve got the time though, ClothFX will look alot better :D

03 March 2006, 11:34 PM
sorry no WMV here. DivX or Mov?

03 March 2006, 11:49 PM
sure - (
and if you can get wmv, here are a few other shots that I didnt put on the reel...

03 March 2006, 12:37 AM
Nice stuff Howard and I agree ClothFX looks good but its a pain to tweak

03 March 2006, 03:04 AM
if you need to use one large water object make a weight map to fix the points not influenced by the wake (check the calculation time difference if you fix/none in the object supplied)

I assume by using a weight map that you are limiting the area that LW will use for calculations right? How do you tell it to ignore everything outside of the weight map?

03 March 2006, 03:24 AM
BTW, I edited the path of the collision object, I noticed that the calculations stop in the middle of the water, why is this?

>>> set the playback mode to local and re-enable the texture displacement

how do you do this? I've never done that before.

03 March 2006, 07:43 AM
You use the weght map to select the points you want clothFX to ignore by giving them a non zero value in the weight map and selecting that weight map in the fixed drop down list.

The calculations run OK here, sometimes it might appear that it has stopped but if you give it a minute it will complete ( (

03 March 2006, 04:20 PM
I tried the calcs over and over last night and looked for a reason, but on frame 60 they stop. It doesn't matter really. I think I might have my head wrapped around this. Not too sure though.

03 March 2006, 07:10 PM
Okay, I've done 3 test renders with Cloth Simulation and need some basic feedback on what looks the best or what I need to change.

You need Quicktime 7 as they are encoded H264.

wave test 1 (

wave test 2 (

wave test 3 (

1 and 3 may look the same, but they have different depths for the waves. Of course, the simulation will take place over a distance of 500 metres.

And just for fun, the night time scene with the SH-60...
Hover Test (

03 March 2006, 07:04 PM
An update without the hull...

wave test 4 - long without boat (

03 March 2006, 09:46 PM
These are the last 2 tests for the bow wake. They are 2 slightly different items, but I think that this is it. Give your opinions.

Sea Test 05 (
Seat Test 06 (

03 March 2006, 09:58 PM
looking cool! :D

03 March 2006, 12:11 AM
Quick question, does anybody know of some mpg resources of a helicopter flying over water? I want to see how the air and water is affected.

03 March 2006, 09:39 AM
good resources!

03 March 2006, 09:34 PM
Thanks! I spent some 5 hours last night trying to find stuff. I found out that I have a softbody calculation of 339, 352 polygons. All for 500 metres of mesh. Thank god I'm smart enough to know that I can run the boat a couple of times through the same area without the viewer knowing that it's the same water.

I wonder how long it will take to calculate on the Dual G4 867 MHz system...

03 March 2006, 10:11 AM
Not sure exactly what youre doing, but you can tweak things to calculate faster by playing with your Calculation Resolution....try increasing it and you may speed up the calc, without loosing quality.

Also, did you model your ocean with the dense amount of polygons only where the wake will be?
And as said, use weights or pointmaps to turn off the area that doesnt need calculations?

03 March 2006, 06:06 PM can tweak things to calculate faster by playing with your Calculation Resolution....try increasing it and you may speed up the calc, without loosing quality.

Is that "sub-stucture"? My substructure is set to 200. The number of 2-sided polygons is 326,300 as the clothe simulated object (2m cube 100m x 500m) with a 13,052 poly surface linked with HardFX which needs to be subdivided.

03 March 2006, 06:11 PM
huh what are you using HardFX for?
and why is your sea a cube?

anyway, what you want to do is only model the area where the wake will be as hires, and the rest of the ocean can be minimal polygons, and again use weights or points to asign them to fixed in Cloth so they dont get calculated...

the resolution is under the ETC tab, raise it up and test the sim, and you can find faster sims depending on your scale..

also sometimes too much substruture ends up making the sim take longer without much benefit, so try to lower that too...

03 March 2006, 06:42 PM
Here's what I've done for all the animations.

03 March 2006, 11:00 PM
hehe, who told you to do all that fancy crap? :P

well, you can get away with just the upper set of polys as Cloth and no HardFX nor fixed polys at the bottom...

but if that works for you, great!

Im sure calculations would be faster with just the upper layer, and again, anywhere the wake wont be, make that as few polys as possible, and use a weightmap or point set and name them so you can make them fixed...that way, the sim doesnt take all the extra water into account...

if you can get your hands on Realflow or have a mate that uses it, ask them to make you an ocean model. Realflow has a cool technique where you can make a center circle of dense polygons, that are all connected and taper off to the edge with fewer great in LW....
Or you can model this by hand, but its a pain...

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