View Full Version : ClothFx Flag tutorial LW2018

James Moore
03-07-2018, 01:33 PM
I've been trying to do the flag tutorial in LW2018. the tut is the dynamics tutorial https://www.lightwave3d.com/learn/article/dynamics-creating-a-flag-blowing-in-the-wind/

I've noticed that the interface has changed since they made that tutorial and I think that I have managed to do most of what is specified in the tutorial through the different menu locations but I can't seem to get the fix points portion to work at all like what occurs in the tutorial. My flag just falls with gravity. The wind will blow it away but I can't get it to stay in a spot and flap in the breeze.

I've tried adding a pole to the scene and parented the flag to the pole but that doesn't seem to help. I can't seem to find a way to fix the points to the pole either.

I must be missing something. How would one make a flag fly in the breeze attached to a pole in LW2018?

03-07-2018, 06:02 PM
I've not tried this on 2018, but I just watched the video and the only thing I can think of is to ask are you using ClothFx or are you using Bullet. If you're using Bullet, you have to use a different method. Use your selection set to help you create a weight map that you can use in Bullet to anchor the side of the flag to the pole.

Good Luck,

03-08-2018, 05:08 AM
check this flag scene, should work

rightclick to download

James Moore
03-09-2018, 05:05 PM
Thanks for the suggestions! I took a look at that tutorial and he created a selection set to fix the flag. He then cuts to the animation and the points are fixed. When I do that it doesn't fix. It just falls.

I am not currently using Bullet for this effect but rather with ClothFX accessed through the object properties window -add modifier. There you add ClothFX to the object. You can then access the variables in the tabs as mentioned in the video by double clicking ClothFX in the list. Under the Etc tab you can set the Gravity and select the type of Cloth you want. Under the basic tab is where you select Fix. I can select the Section set I created in Modeler. Unfortunately when you click "calculate" the Flag object just falls in the direction of the Gravity. Nothing gets fixed.

I'm not sure how using the weight map method as suggested in that other Flag Tutorial. He Fixes the flag the same way with the selection points.

I did at one point try attaching the flag to a pole using Bullet but I couldn't figure out how to do it. My understanding and use of weight maps is not very good. It is something I'm trying to grok. For example, when I create a weight map in modeler the map falls off through a 1 polygon radius. I'm sure there is a way to control this but I haven't sussed it yet. How would you attach a flag material to a cylinder? The pole should be a kinematic object I believe and the flag a ...

03-09-2018, 05:29 PM
should work, at least in LW11.6 (no audio)


...did you test the scene i linked?
if no, why not.

03-09-2018, 06:18 PM
IMO, Bullet is the way to go.

In my Asylum VFX Reel from 2015 (https://vimeo.com/209695539), there's a flag being pulled by a plane towards the end of the reel. This was done back when LW 2015 was still in beta and it worked out well. I only had a couple of days for these shots, including building the environments, mocapping the robot (using iPi Studio in my living room!), animating the plane, lighting the scene, and building the flag stuff...so I didn't want to spend a whole lot of time messing with the dynamics. Fortunatly, these Bullet sims only took a few minutes to run.

The only issue I ran into was that I was using the new (at the time) Point-to-Point constraints with bones and I found that I couldn't sim both the tow rope dynamics and flag cloth dynamics at the same time. What I wound up doing is running the Bullet rope sim first, then scanning a point at the end of the rope using SoftFX, and baking the point's motion to a null. (There's a command in the SoftFX panel for this.) Then I attached my flag contraption to the null and ran the cloth half of my sim. Easy peasy.

As mentioned, I was using the beta version of Bullet Constraints, so the double pass trick it might not be necessary these days.

In any case, the flag part was pretty straightforward with Bullet. To pin the corners, just apply a weight map to the points and set them in the Mesh filter. Also, make sure cloth mesh is has suitable density if you want small folds and wrinkles. For wind, I probably just used a turbulent texture in a Bullet Wind effector and dragged the flag through it using the baked null. If your flag is on a pole, you can skip the 'dragging' part. :)

Hope this helps.

03-09-2018, 07:01 PM
for Bullet also check >

James Moore
03-10-2018, 09:11 AM
I am wondering if the problem with fixing the points is a bug in LW2018.

I didn't load the scene the first time erikals as I didn't realize you'd setup a scene and stuff. I downloaded it and it worked. However, on loading, it warned me it was made in an older version and it would be translated and things would be lost. The ClothFx Ect tab is set up different than what you showed in the video - there is no gravity set in the Ect. tab. I noticed that you have weight maps on the object Plane2. Your video didn't show you setting up weight maps.

The video you posted is the basic set-up I am doing:
create Plane in Modeler. Select points on edge of plane, create selection set called "Fix". save object. Load in Layout. In object properties add ClothFX. Under Basic/Fix select "Fix/pointset". In Ect. tab set Gravity to -9.8 in y direction. click calculate and plane falls with nothing fixed.

James Moore
03-10-2018, 09:40 AM
welp, I got it to work. It puzzles me though.

The change that made it work was I need to model the plane in Modeler in the XZ axis portal. Then the points fix. If I model the plane in the XY plane the points don't fix.

That sounds like a modeler bug to me. Is there a way to report bugs? Or am I missing something...

Thanks for all your replies and thoughts on this!

03-10-2018, 10:17 AM
hi, good to see it sorted out,
could be a bug

in LW2018, go here to report bugs


03-11-2018, 11:53 AM
The thing with ClothFX is that it's old, and I mean really REALLY old. I first used it for a creature effect in a B-movie way back in 2000 or 2001, and there's been very little development with ClothFX ever since. I relied on CllothFX for about 10 years for cloth and hair sims in video game cinematics and TV commercials, but after Bullet Deforming came out for LightWave I really haven't bothered with ClothFX. Bullet is easier and faster to set up, and the result is more predictable.

Anyway, what I'm saying is that you can submit a bug report to LW3DG for CothFX but I wouldn't expect them to do much about it. Any request for improvements in cloth dynamics in LightWave is more likely to to happen with Bullet or in a more modern system in a future release.

BTW, for flag animations, a good 'quick and dirty' trick is to simply drag a fractal displacement through the material. This is an old school trick but it's pretty convincing when the flag doesn't need to interact with anything--which is most of the time for decorative flag effects. I still use this trick when I think it's appropriate and I don't have time to mess with dynamics. (You'll still need a weight map to grad the falloff at the corners and edge attched to the pole.)

Another good alternative to ClothFX for realistic sims is the third party Syflex, which recently got an update for 2018.

James Moore
03-12-2018, 03:03 PM
I just discovered that the variable that caused the problem is not what portal you model the flag plane in but whether you use the 'tab' key or not . If you tab it (metanurbs? - I see it changes subpatches) Anyway if you tab it and save the object then the fix points don't fix. Note: I was just informed via my bug report that if you put subpatches ahead of ClothFX in the modifier stack it'll work as expected.

I've been away from the details of Lightwave for a bunch of years and only dealing with LW in a supervisory role. Now I'm getting my hands dirty, having some fun - well trying to anyway and I've purchased LW2018 to do it. I am a bit of a noob.

One thing that interests me is the use of 'real world' physics in the 3D universe of lightwave. I am most interested in trying to get real world like physical behaviour happening in Lightwave. I realize making it 'look like' is the most expedient way to go especially when deadlines loom and often it is the only way to get what you want in the end.

I've enjoyed your posts Greenlaw and now that I've figured out the fix point thing I am exploring fixing the flag to a pole so that when the pole is moved the flag responds as it would in the real world. I'm not sure this is possible... I will also try baking in the motion and then attaching it to the pole.

03-12-2018, 03:21 PM
Thanks for posting your info. That's very interesting about the order requirements for 2018.

FYI, be aware that Bullet calculates using actual geometry, not Sub-D surfaces. For example, if you're using Sub-D surfaces, the collision may not be accurate because it's actually using the un-subdivided geometry. Sometimes this isn't a problem, but if you really need the accuracy, use a 'frozen' divided version of the object for the calculation.

James Moore
03-12-2018, 03:33 PM
I was just hacking away at it - you need to put ClothFX ahead of (on top of) Sub-d in the stack. I also found that if I parent the flag to the pole and turn off bones the flag with the ClothFX active will go with the pole.

James Moore
03-12-2018, 05:14 PM