sylpaco
Hi there,

This is a rough test to generate, proceduraly, particles between 2 objects.

Now, particles are generated by a curve based on point cloud coming from bounding object of the surface and point cloud from the other one.

My question is : is it possible to use pointcloud as an input geometry in the bounding object node ? because now, my collision detection depend of the mesh density and not of the volume or the surface.


thanks




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pshipkov
Very cool tests man.

Yes. The bounding object nodes can accept mesh, curve, surface and point clouds (listed as "particles"). I am not 100% sure how you generating the point clouds, but in SOuP there are nodes that can extract that data and you can pipe it as vector arrays to boundingObject.inPositionPP (under "particles"). Then set boundingObject.mode to "geometry".

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sylpaco
Thanks, also, are there news about pointCloudParticles emitter ?

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pshipkov
I never planned one really, but we can talk about that here if you want. Do you have any specific requirements, or just like the way the pointCloudFluidEmitter works and think that similar approach for particles will be good too ?

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sylpaco
nothing specifics, just the same parameters than the nParticles and particles emitters :O) dont hesitate to let me know if you want a tester :)
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pshipkov
Got it.
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toho
I want  pointCloudParticlesEmitter too  :crazy:
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pshipkov
I have a question for you guys - this can be "hacked" with scatter and standard particles real easy, even with standard particles only. Is that not good enough for you, or the workflow is clumsy, or there are other limitations that you feel are a deal breaker ?
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toho
You mean bake point cloud to curve an then emit from curve? or other work flow exist
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pshipkov
Ok, let me explain little better.

To emit particles from particles we have two options - to use the first point cloud as standard Maya emitter. That's easy but very limited.
The second option is to use the "emit" command in dynamic expression attached to the first particle shape. This way we can make the second particle shape inherit PP attributes from the first one. This is powerful but the workflow is very unintuitive and requires a bit of setup.

Another problem is if we want to emit from mesh surface, to say, and want the mesh point properties to affect our emission. This is the common procedural workflow that Maya so badly lacks.
In this case you will need SOuP to ease the pain, otherwise we have to scatter one set of particles on the mesh surface using randomized UV goal attributes. Then the only option we have is to read vertex colors using the colorAtPoint command (very slow). If we need to sample more data than the R G B A channels things go bad.
Finally using the "emit" command we make the second particle shape do the right thing we are after.
So this sounds like very negative overview, but in the most cases it is ok.
With SOuP we can simplify this a lot. We can use the scatter node to scatter some points on the mesh surface then use attributeTransfer to transfer some of the mesh properties to the points. Then we can use this point cloud to emit particles and finally we can use second attributeTransfer node to procedurally pass data to the second point cloud.
We end up with few more nodes in the scene, but no scripting particle expressions that can get quite hairy and slow in many cases.
There are few examples in the "scenes" archive (mainly from Sergey) that show few of these configurations.

Basically, what i am saying this can be achieved already in Maya but on the expense of bad workflow and you are right that pointCloudParticleEmitter can be very handy in many cases.

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DickyT
I get asked to make a lot of small dust elements, and I think pointCloudParticleEmitter would really save so much time.

:p

Segway all the way!
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toho
Thanks for such deep explanation.
What about me just want more straightforward work flow.
I if it difficult to implement or more prioritized tasks exists I would give up
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pshipkov
I consider it valid request and have it on top of my to-do list.
I am going in vacation for 2 months so, this may take some time.

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pshipkov
I consider it valid request and have it on top of my to-do list.
I am going in vacation for 2 months so, this may take some time.

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