Cache Operator - Memory limit?

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  07 July 2014
Hi thanks. I appreciate my scene is unusual... The two worlds was the only way I could get it to work. The scene involves a few hundred blood cells flying through a vessel which start to collect around a blockage.

It starts with a normal/old style flow, then uses the mP Switch to convert to mParticles physx for the coagulation, using Glue. For some reason the blood cells wouldn't bind to my collision object in the same world, the only way I could get it to work was to send them to a new event with a new world - then it all worked. I spent hours fiddling around, and this worked!

I do have a fast SSD drive, but the disk caching operator didn't solve the problem. Unfortunately I don't have budget right now for any 3rd party plugs, otherwise I'd be all over XMesh!
 
  07 July 2014
Maybe post a screengrab of your flow. I am curious to see what you setup looks like. You may be having other issues. It would be best if you could post your scene to help troubleshoot but I can understand if can't.
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poof ~>Vimeo<~
 
  07 July 2014
Perhaps the cells that aren't involved in the MParticle coagulation could be regular particles with shape instances? Then you could cache just the particles positions (not shapes, which makes for a much smaller cache) and replace those realtime with a post-cache operator like JohnnyRandom helpfully demonstrates here:

http://vimeo.com/95607037

(JohnnyRandom, your Vimeo video appears to not be embeddable.)
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--Pel
 
  07 July 2014
Got moved onto something else... but had a chance to come back, thanks for replies.
Johnny Random, I can post a grab of my flow, but can't work out howto post an image - [IMG]Screengrab[/IMG] - what am I missing?!

So, I tried caching just the 2nd World (the one with the glue). When I cached both worlds, and baked the glue it all stopped working.

Caching the 2nd World worked, as far as there were no weird thing happening in the animation, it played from start to finish and lloked good. However, when I did an AO pass from the same file, it came out slightly different, particles in different places.

I'm guessing thats because I didn't cache the 1st World... So back I go to try that.

PelDaddy, all the particles need to be in a phys X sim, even the non coagulation ones, as they bounce off each other, and off the blood vessel wall. Useful video though, I hadn't seen Johnny Random's videos - excellent resource!
 
  07 July 2014
Just attach the image with Attach Files below in the Reply page->Additional Options (I think you need 10 posts though before it becomes active)

Or use an image host like imgur
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poof ~>Vimeo<~
 
  07 July 2014
I had not seen that! Cheers.

It may not be the most efficient flow, I'm fairly new to Pflow. It starts with a normal flow rather than birth stream, as I originally had the particles moving along a speed by icon though a complicated path - I want to keep that option in there.

Then I used a switch and an age test (some one told me it's better than a 'send out'?) to send the particles into a physX event, so the collide with each other and with the vessel wall.

Ages test again, and into another event where there is a collision. Looking at it now, I'm not sure why this is in a separate event - it may have just been for clarity; so I could see the particles change colour.

That then goes to the final event where is the glue and the collision event again. I wanted the particles to also stick to the collision object, and the manual said it would have to be in the same event as the glue, which is why it's repeated here. When using the same world as before (world 003), the particles didn't glue to the collision object. When I made a new world in that event (world 009) it started working - so I stuck with that!

I can't upload the scene as is, but it might be possible if I strip the assets... I might be able to do that later!
Attached Images
File Type: jpg pflow_glue.JPG (73.0 KB, 10 views)
 
  07 July 2014
Ah okay, you are breaking some important rules, nothing horrible but they will effect the way everything works.

First off, this seems simple, if you want massFX physics in an event you need to have a "mP World Operator". This is different from an "mP World Helper". The difference being the operator is an event node, meaning it is used in Particle Flow within the Particle View and the helper is a scene node, meaning it resides in the Viewport. You should one have only one "helper" in the scene and as many "operators" as you need in the Particle Flow. For example, in Event 003, your mP World operator is accessing a totally different mP World Helper, it should be using "mP World 003" as all of the others are.

Secondly you cannot legally change shapes in an mP Flow. The PhysX engine currently only allows a single mesh instance per particle. You can change the "look" of it with a different mesh but the collision hull will always remain the same. You typically only need one Shape Operator followed by a single mP Shape and all shapes will propagate downstream.

Same goes for mP Shape you only need one per flow the workflow is to put it in the same event as the first mP World.

mP Switch only works in the event that it resides in. For instance since the PF_START event does not contain a mP World the mP Switch has no effect.

Somewhat shameless plug, I would suggest going through the Box#2 Visual Guide (what it was called before mParticles) It is a good resource to get you started in properly using mParticles with PFlow...
http://www.orbaz.com/visualguide/pa...flowtools/box2/
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Last edited by JohnnyRandom : 07 July 2014 at 08:44 PM.
 
  07 July 2014
Thanks for that Johnny. I should have said, I'm not that new to Pflow, I've been using it, and mParticles for a while, just not a master!

I understand most of what you wrote, but for some reason, that flow works! I cached both worlds, and now there are no weird freakouts, and I can do multiple passes. It's not perfect; there are some intersection with the wall and stuff, but the main coagulation effect works.


As I said, with only one world operator, the glue doesn't work on the collision object. The only way I could get it working was to filter that info into a new event with it's own world.

I don't quite understand what you mean about the shapes... Do you mean you only need one mP shape operator in the entire flow? I thought you needed it in each event where you needed PhysX.

I put the switch in because I thought I needed to switch between 'normal' and PhysX - but I take it it's only needed to switch the other way around?

Appreciate your help!
 
  07 July 2014
Originally Posted by OllyV: Thanks for that Johnny. I should have said, I'm not that new to Pflow, I've been using it, and mParticles for a while, just not a master!
No problem, It is always hard to tell a user ability when all you have to go by a a low post count and a very new membership date
Originally Posted by OllyV: I understand most of what you wrote, but for some reason, that flow works! I cached both worlds, and now there are no weird freakouts, and I can do multiple passes. It's not perfect; there are some intersection with the wall and stuff, but the main coagulation effect works.
It is always supposed to work! The idea being if you want collisions/interaction within the same system, no matter how many different Sources/Events, you use the same World Helper. You could have a different World in every event if you wanted to, particles just wouldn't interact with the previous World.
Originally Posted by OllyV: As I said, with only one world operator, the glue doesn't work on the collision object. The only way I could get it working was to filter that info into a new event with it's own world.
That is strange, I would have to see your Glue, Collision, and Collision Shape modifier settings to determine the issue.
Originally Posted by OllyV: I don't quite understand what you mean about the shapes... Do you mean you only need one mP shape operator in the entire flow? I thought you needed it in each event where you needed PhysX.
You only need one mP Shape per mP World Helper, so yes, for the most part is is true of just standard PFlow, shapes propagate downstream.
Originally Posted by OllyV: I put the switch in because I thought I needed to switch between 'normal' and PhysX - but I take it it's only needed to switch the other way around?

mP World Operator determines whether you have PhysX in an event or not. The mP Switch will turn off certain particle attributes within a PhysX event.

Originally Posted by OllyV: Appreciate your help!
anytime

Even if you don't read it all, you should go through the Visual Guide link I sent you earlier, it makes me feel good for all the time Oleg, Jeff, and myself spent putting it together, that it actually gets used. It explains a lot of basic to moderately complex usage for mParticles.
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poof ~>Vimeo<~
 
  07 July 2014
Hey Johnny,

The guide definitly get's used! I referred to it often, back when it was all Box Tools. I think I did every tutorial, even the spaghetti and falling sheets of paper ones

Appreciate everyone's help on this - it finally did get sorted and I learnt a lot on the way!
 
  11 November 2014
Sory for resurrecting this old thread, I just wanted to mention, that I in fact didnīt know the visual guide! Great ressource!
 
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