Particle Emitter Random Problem

[Jeanny]

Particle Emitter Random Problem

Can someone please help me with the problem I described in the attachments?
Rather than typing it all out while on line I made a couple of screen shots of my "Pages" document.

I've also included one of my last attempts in which I made a big mess and don't know how to undo the mess.

I kept trying one thing or another and it just "snowballed".:tongue:

My Best
Jeanny

 

[podperson]

You should get your first few requirements for free from perspective / parallax. Just use an emitter with depth and adjust perspective to taste.

Clumping is just a matter of picking the right random number seed or artfully using effectors. This was literally my first attempt with no effectors. All I did was change gravity, initial speed, and spawn rate.

 

[Jeanny]

Thanks for replying Pod
I thought I attached a jas file but I see I didn't.
After giving my post more thought
I don't believe I defined my questions with the specifics of what I'm trying to accomplish adequately.

Also I was asking two questions and I think I should address each one separately.
I am having difficulty articulating my questions; thus I will try to express them better and add a jas file later today.

Thank you for replying Pod.
You expressed it is a matter of picking the right random number seed.
I had tried countless variations of the random seed to no success.
I was hoping their may be another way.
I myself had tried the Gravity effector but found just using the emitter worked better.

The example you posted still has the clumping I am trying to avoid - however
I do appreciate that you took the time to try to help me.

My Best
Jeanny

 

[frank beckmann]

Not sure if this is any better - I use a polygon grid as an emitter mesh:

Cheers
Frank

 

[podperson]

If you want to control the position of the particles use a particle mesh and then use the particle tag to precisely control position randomness.

 

[frank beckmann]

If you want to control the position of the particles use a particle mesh and then use the particle tag to precisely control position randomness.

Yes - when it´s not for animation purpose - but I´m not sure about it. :redface:

Cheers
Frank

 

[podperson]

Yes - when it´s not for animation purpose - but I´m not sure about it. :redface:

I think it works (unless something has changed). My original jellybean bowl example used particle meshes + gravity to fill a bowl with jellybeans. (You'd need to create the entire grid of snowflakes from the mesh in one shot though, which is what I think you're getting at).

Making a perspective collection of snowflakes that never clump is going to be a bit of a pain in the neck though

 

[podperson]

How about using a bunch of carefully positioned, slow emitters? Note that each emitter has a different seed!

 

[frank beckmann]

I think it works ...

I meant I´m not sure what Jeanny wants to have in the end. :wink:

Cheers
Frank

 

[podperson]

I meant I´m not sure what Jeanny wants to have in the end. :wink:

Ah, you and me both, evidently!

 

[Jeanny]

I'm very sorry for not being able to post a reply to your generous attempts to help me today. Life got in the way today. Tomorrow should be a better day in which I can formulate a half way decent explanation with pictures and a jas file of what I'm after and what I have tried.

@ Frank
I don't know if there is something wrong with my computer or my internet server; but the illustration you posted shows as a question mark in a box. I've posted a screen shot of it. I would very much like to see what you posted.

@ Pod
Thanks so much for attempting to help me again. I took a quick look at the file you posted and will comment tomorrow when I've had a chance to experiment a bit. You gave me some good ideas to try.

Again, I am sorry I couldn't get to it today... besides I am slow to understand technical things and I get tired early.

Good Night - Sweet Dreams
My Best
Jeanny

 

[Jeanny]

I'm sorry this post is so late at night. Today ended up being another day that
prevented me from working in Cheetah as much as I wanted to.

My post is so long that once again I thought I'd just submit several screen shots of it.

I was going to attach one of my .jas test files but it was rejected because it was too large.

With my Best Wishes
Jeanny

 

[Helmut]

Nitpick

Hi Jeanny
Snowflakes are all structurally hexagons, due to the shape of the H2O molecules and their bonding geometry. You may have a good reason to show them as octagonal crystalline polys, but some pedantic nitwit (see representative portrait attached) will come along and complain :tongue:

 

[Helmut]

* Getting an evenly distributed emitter with such a small birth rate seems to be very tricky, indeed. Like you, I get a bunch right (or left) but no even distribution without clusters and holes.

* The only improvement I could achieve was by implementing a clumsy trick:
* Increase the birth rate.
* Add dummy particles and set them invisible.

 

[frank beckmann]

How is this?

No trickery - just a birthrate of "1".

Cheers
Frank

 

[Helmut]

* Results seem to be a matter of the ratio size of flake vs size of emitter:
* smallish flakes on a lengthy emitter do not distribute well, whilst
* largish flakes on a smaller emitter seem fairly evenly spaced across the view port.
* Mathematically, this makes sense as randomness combined with a small population, a short interval and widely spaced emission points will hardly ever be balanced.

* My first tests with a long thin rectangle to simulate a “curtain” of smaller snowflakes generated the mentioned clusters and holes.
* Switching to a “close up” of the flakes, i.e. larger flakes and smaller emitter as in Frank´s example gives a quite balanced distribution.
* In the end it depends on how you compose your scene

 

[podperson]

Given your very particular requirements it might be easiest to use a custom (scripted) particle emitter.

Also, I'm puzzled as to why you post your requirement text as images, it makes it very hard to review them while writing a reply

If you don't want much perspective, my "lots of emitters" approach should do the trick; you may actually want to use the SAME seed, or even use a non-random grid particles. You could even create a grid of emitters and manually animate them past the camera (possibly even creating a looping animation)

 

[Jeanny]

Helmut, Frank & Podperson

Thank you so much for continuing to help me! Thank you for your intellectual benevolence!
Looks like a lot of good advise from all of you.
I think I can combine some of your ideas.
I will experiment with your suggestions and get back to you as soon as I can.
It will take me some time to do so.

My Best Wishes
Jeanny

 

[uncle808us]

How is this?

No trickery - just a birthrate of "1".

Cheers
Frank

All I see is the little blue square with the question mark center.

 

[frank beckmann]

All I see is the little blue square with the question mark center.

I have no clue what´s going on:
Which browser do you use? Maybe make a right-click on the square to open the AnimGIF/image in an extra window.

Cheers
Frank