Smoke with stroke brushes and opacity

[heyvern]

There is a cool video about a year old that shows of the new "color offset" stroke shape feature. As a side note towards the end he shows off a wicked cool trick using a stroke with a brush to create a very simple but convincing smoke effect.

Part of the process is how pulling on the end of a point of stroke shape with brush causes the brush to spawn from the base point. So you set the opacity of the end point to 0 and animate it moving and the brushes keep moving from the base point. I've tried and tried to recreate this trick, but sadly, with the shapes I create for a single stroke, the brushes do NOT generate from either end; they always come out of the middle of the stroke. So the opacity on the end point (either end) simply does nothing. The point animates but no smoke movement as the point moves. Is this a change to how brushes work in moho or am I doing something wrong? Is there a specific trick I'm missing?


Go to time stamp 32:23

[synthsin75]

This worked in 14.3 but not 14.4.

[Víctor Paredes]

Hi. I wasn't aware of any potential issue related to this technique and don't remember any addition or modification made on 14.4 that could be changing this behavior.
I just tried to re create the effect here and it is working.
Could you share a file where it doesn't work, so maybe I can find what is going on?

[synthsin75]

Here you go, Victor. It helps to turn jitter to 0%, so you can see the stamps only get added to the curve segment being lengthened.
https://gofile.io/d/GY09wj

[heyvern]

i spent about an hour fiddling trying to find a workaround using only two points. sadly no luck. i ended up using smoke images and particles which worked even better

[Maestral]

I don't know how much does it helps you, but I've managed to recreate the effect, from the video. I've followed Victor's steps, and it works just as it's expected.

However, I couldn't make the stroke generate from the centre, so I was wondering if you'd share the step-by-step on how you made it since I'd like to use that effect (generate from the centre).

[synthsin75]

I don't know how much does it helps you, but I've managed to recreate the effect, from the video. I've followed Victor's steps, and it works just as it's expected.

However, I couldn't make the stroke generate from the centre, so I was wondering if you'd share the step-by-step on how you made it since I'd like to use that effect (generate from the centre).

Does the file I posted work correctly for you, in v14.4?
https://gofile.io/d/GY09wj

[Maestral]

I've made a few tryouts and finally figured out what it was all about - Jitter Angle / larger than 0 - in Brush settings.
Even yours is working when the brush is adjusted.

If Jitter Angle is set to 0, then it acts in "both directions".

p.s.
During the tryouts (with JA at 0) and on the line with 4 points in total, I think I noticed some different behaviour caused by the order of creating points and when a shape is created, but didn't really remember which is which. For example, do you create a line and then add points to it, or do you create a line from (continuous) segments? When is a shape created? Before all points or points and then a shape...

It all manifests while you drag points and where the origin is, from which the brush is generated/filling the length of the line or a given segment.
For example, in one case, dragging one end acts like a passive (gen. is just between the given 2 near points) and if you drag the opposite end, gen. comes from the middle (at least 3 points in play). As expected, I'd say, but the range of the "middle" varies due to the mentioned cases/order of creation.

[heyvern]

I got it to work, starting from scratch with a new file. However, the original file that was not working was still broken even with jitter angle above 0 (it always was above 0, I never changed the defaults). It still generated brushes from one end of two points only. So three points, they pop in from the middle point.

Good news, it DOES WORK, but bad news: if it's broken, it's difficult to figure out how to fix it. Requires trial and error. Make a change, and close the brush editor, test, try something else. I went back to my original file that didn't work. Jitter angle was 360, and it was not working. I randomly fiddled with all the settings, turning on and off, setting to 0, etc., etc. After fiddling, I got it to work. I was not scientific and dont have time to find the actual fix at this time. It took a while, though, and I'm not certain what worked. At some point in the fiddling, I add an extra point. Not sure if this made a big difference.

End result, if you start from the beginning from scratch and don't change brush settings and the starting shape has the correct options, it appears to work as expected. If I figure this out will post it here. But yes, I had a file with above 0 jitter that was only generating brushes from a point between two points and not from the endpoint.

[heyvern]

Here's the final effect I needed this for. It's that thin puffy smoke coming out. The other smoke is particles.
And yes, uh... er... it... uh... well... it represents some illicit use of controlled substances being blown out of a door.