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Roque
02-15-2016, 10:59 AM
Hi all! (excuse my english)
I need generate droplets on the surface of a bottle.
I want to use instances to distribute drops on the surface, this has the advantage that instances perfectly follow the animation squatch and strech of the bottle.
On the other hand, I want to use HyperVoxels for rendering. Thus nearby drops stick together.

There any way that HyperVoxels can be applied on instances?

Thank you,
Roque

erikals
02-15-2016, 11:54 AM
nope   http://erikalstad.com/backup/misc.php_files/smile.gif

you can (somehow) clone points in the same locations as the instances, the apply HyperVoxels, but that's about it...

MonroePoteet
02-15-2016, 12:56 PM
What I'd do is create a "Droplet" layer / object in Modeler containing points on the surface of the bottle by using Random Points, BG Conform, Jitter and Twist.

Here are the specific steps I used:

1) Create a hi-res version of your bottle with a lot of points on the surface
2) Switch to Layer 2
3) Put your bottle in the background layer using ALT-1 (assuming the bottle is in Layer 1)
4) Use Create=>Points=>Random Points to create however many droplets you want, say 300 in a sphere
5) Move the Points to center on the Bottle
6) Use Modify=>Translate=>BG Conform to line up the random points with the points on your hi-res bottle
7) Use a small Jitter in the Y axis to offset the droplets off the actual points in the background layer
8) Use Twist on the Y axis to offset them radially a small amount
9) You'll want the droplets layer parented to the bottle layer for FX_MetaLink in Layout
---- you can cut-n-paste the droplets layer into a separate object, which is what I did
---- you can do this in Modeler using the F7 Layers panel to name and parent the layers
1-) Send the object(s) to Layout
11) In Layout, parent the Droplets to the Bottle if you didn't do it in Modeler
12) In the Droplet's Properties Deformation tab, add FX_MetaLink
13) In the Bottle's Properties FX tab, add Hard (this sends the bottles points to the FX subsystem)
14) Use Hypervoxels to set up whatever water droplet surface on the Droplets that you want
15) FX_MetaLink will cause the points of the Droplets to deform with the Bottle's points as it is stretched, bent, etc.

Attached is a sample scene. I cut-n-paste the Droplet point array to a separate object instead of leaving it in a separate layer of the Bottle object. Remember you have to use VPR to see the HVs.

Note that although the position of the Droplet points will conform to the deformed Bottle, the HV's themselves will retain their original shape.

Good luck!
mTp

MonroePoteet
02-15-2016, 01:07 PM
P.S. More experimenting shows the Jitter and Twist in the above description are extraneous. FX_MetaLink lines up the points of the child with the exact positions of the closest point in the parent, so offsetting them doesn't matter. Just make sure you have plenty of points in the hi-res version of the Bottle so the Droplets don't look aligned or too regular.

mTp

Roque
02-15-2016, 05:24 PM
Thanks erik, the problem with this method is that it can not keep "editable" the distribution of instances. And the main problem is that the drops are not "stuck" to the surface deformations.

Thank you Monroe!, honestly I never remember that I have metalink among the possible tools :)

However, it would be that simple if hypervoxels read instances of an object, as do with the particles, hey developer team! a "simple" idea here! ;)

Thanks,
Roque

erikals
02-15-2016, 05:49 PM
looked at it some time back, it's actually quite difficult to animate...


https://www.youtube.com/watch?v=iggHE-xTkw8

jwiede
02-15-2016, 08:58 PM
looked at it some time back, it's actually quite difficult to animate...

It's an insanely complicated dance of surface tension, condensation rates, and gravity. Simulation is a painfully complex proposition (though the field lines notion is interesting). Getting droplet formation/growth/runoff behavior that looks "adequately realistic" can be, as Erikals notes, quite difficult.

This is for animation, then, not stills? Thats... tricky. You might almost be better off capturing video of real condensation, and somehow using that as an animated texture to drive things.

erikals
02-16-2016, 02:03 AM
You might almost be better off capturing video of real condensation, and somehow using that as an animated texture to drive things.
+10
thought about making a paid tutorial about that some time back, but then again... > time...

Julez4001
02-16-2016, 12:18 PM
What about that old tutorial (cgtalk) where you see the blood droplets outside of the egg shell?

Anyone else remembers this, I have a .pdf of at home somewhere. It was hypervoxels but photoreal.

erikals
02-16-2016, 01:07 PM
those didn't blend though...
but maybe that could be an option, can't recall the technique...

Julez4001
02-16-2016, 06:27 PM
http://www.altyna.com/lw/droplets.htm

Found it.

jwiede
02-16-2016, 07:58 PM
http://www.altyna.com/lw/droplets.htm

The technique described above isn't likely to work well for something like a cold can or bottle -- droplets forming semi-consistently across the entire surface, growing and coalescing, then running down as drops. Instead, the cited technique in the link is more for when a big drop or splatter lands on a surface and slowly dribbles down the surface, singular or in small numbers. Even for that, calling it realistic-looking is going a bit far, IMO.

Julez4001
02-17-2016, 09:56 AM
well I mean it as a starting point.

You could make a series of tightly close points to form a stream and have other voxels intersect from a different group. You could also have morphs on the points to change length and shape.
A lot more work than a liquid sim but maybe a little technical imagination.