mesh particle emitter and clipping plane

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andromeda_girl
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mesh particle emitter and clipping plane

#1

Post by andromeda_girl » Tue Sep 10, 2019 11:20 am

i am doing some testing with a water surface, trying to see if i can get the peaks of waves to emit particles.
i haven't found a way to get a heightmap to work for this, so i went basic and added an image plane set to 'is matte' to clip my water surface so the only geo remaining are the top tips of the waves.
all good so far.
but when i set my particle emitter to use that mesh as a emitter region the entire mesh is still generating particles.
what might be wrong there?
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ShadowMaker SdR
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Re: mesh particle emitter and clipping plane

#2

Post by ShadowMaker SdR » Tue Sep 10, 2019 11:36 am

My guess is that it uses the actual geometry, not the optical result of your operations.


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Re: mesh particle emitter and clipping plane

#3

Post by andromeda_girl » Tue Sep 10, 2019 1:08 pm

that is what it looks like to me as well [sigh]

i have switched to placing a camera above my water surface to output a bitmap render and use that for a bitmap region for the particle emitter...
but that strangely generates exactly what i want but turned on its side for some reason and not facing flat.
O_o
if i add a transform 3D i can flip it back again, but then merging that over the water it is 1/4 the resolution, and i cannot find just where this scale down is taking place.
-again: O_o

the output of the bitmap render is 4K, and i was expecting the particle results to at least fit the same as the geo for the water surface.

and if i plug the geo in, it lays flat and matches the scale of the source geo, but just doesn't respect the clipping plane's work.
pretty odd results.

Added in 28 minutes 20 seconds:
cannot find a setting that lets the clipped mesh become the 'actual' mesh...
:(
and,
i cannot find a setting that lets using the bitmap option match the scale of the mesh, either.
:(
i am forced to scale it all up for the bitmap option to work- but then the particle output is terrible because it's all resized.
:(
and if i run the particles through a render 3D, fusion totally locks up and dies.
:(

Added in 4 minutes 8 seconds:
what i think i'd need is something like a 3D channel boolean tool but i. don't think there is one?
the krokopdove tools come top mind but they aren't working ion fu16 are they...
oh sigh!

Added in 27 minutes 6 seconds:
what confuses me about this is that i know it has to be possible because Rony was mentioning using a clipping plane to generate particles where you want them in the anonymous demo- so it must be something simple i am missing here.


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Re: mesh particle emitter and clipping plane

#4

Post by Midgardsormr » Tue Sep 10, 2019 3:16 pm

You might be able to use something like what's described here:
viewtopic.php?f=16&t=1929&p=14968

I haven't looked too hard at it; no time at the moment.


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Re: mesh particle emitter and clipping plane

#5

Post by martinamv » Fri Sep 13, 2019 2:55 am

Hi there, what I typically do in these situations is to use the complete mesh for emitting the particles and use a pKill to kill the particles which I do not want to have. Hope that helps.
Cheers, Martin


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Re: mesh particle emitter and clipping plane

#6

Post by andromeda_girl » Fri Sep 13, 2019 7:47 am

a simple enough solution i guess ;)


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Re: mesh particle emitter and clipping plane

#7

Post by martinamv » Fri Sep 13, 2019 10:17 am

yep…

The example shows a text which is supposed to sit a bit submerged under water (a river).

3DMesh plus pKill.comp

Cheers, Martin

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Re: mesh particle emitter and clipping plane

#8

Post by French_Fry » Mon Sep 16, 2019 8:37 am

Another route ( and possibly what Ronay did) is to render out your clipped plane into a black and white image from an orthographic top down camera . Then you can use that as a bitmap emitter, emitting from the white spots that animate in and out. It should then match up with the geo.
The cool thing I've seen from some comp artists in Fusion, in going in and out of 3D to 2D through a camera and then piped back into 3D. So you don't even need to render the images. Just pipe the 3D render into the emitter.
All theory, but it should work.


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Re: mesh particle emitter and clipping plane

#9

Post by andromeda_girl » Mon Sep 16, 2019 10:15 am

i tried that first, actually.
the result was bizarre:
it put the particles on it's side, forcing me to add a transform 3D after the p-render tool to rotate it flat on the ground again.
but then it got weirder:
it refused to render to the same size as the actual geo output was being rendered to.
nothing i do will make the render output larger and match my render output, it stays at 1/4 the scale of my scene--

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Re: mesh particle emitter and clipping plane

#10

Post by French_Fry » Mon Sep 16, 2019 10:30 am

ugh...when theory meets reality...hmm

would love to take a look at your comp if you had anything you can share. :) very curious, and would love to learn something.


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Re: mesh particle emitter and clipping plane

#11

Post by SirEdric » Mon Sep 16, 2019 10:38 am

This setup sort of works for me...:-)

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Re: mesh particle emitter and clipping plane

#12

Post by andromeda_girl » Mon Sep 16, 2019 11:38 am

i found that just using a plane as a kill region worked :)
-now if i can just figure out the little splashes of foamy wakes......