View Full Version : Hypervoxels/Particles Suddenly Disappear - HELP!

10-22-2009, 03:27 PM
Hi all!

I'm working on a scene where liquid rolls around in a space for a bit, then continues down a passage.

I'm using a particle emitter with Hypervoxels enabled. Object Type = Surface, with blending enabled. The particles begin emitting at frame 70, and the emitter is parented to a null that moves around, leaving a liquid "trail" behind it (it has a 15 frame life time.) It calculates fine, and shows the little preview orbs in layout that show up when "show particles" is turned on.

If I render it, though, the particles appear up to frame 76. After that, GONE. Even other hypervoxels in the scene have disappeared. Why? Does Lightwave have some sort of hidden particle limit with Surface on? If I change from Surface to Sprite or Volume, they show up, but that looks like smoke and that's not the effect I need. I want the particles to blend like water. There are under 10,000 particles... It shouldn't have a problem with that, right? I also packaged the scene and tried rendering on another machine, and no joy! What is going on???

10-22-2009, 04:34 PM
Change your particle lifetime parameter to 0.
Then the particles won't die.... ever.

10-24-2009, 08:14 AM
It´probably as mentioned above, but it could also happen that particles
kinda disappear if you run out of particles, so make sure you
also have enough particles in sync or depending on your birth rate.(set particle limit, I think default is 1000)


10-26-2009, 06:15 AM
If the lifetime was too short, they wouldn't be showing up after frame 76 in Layout, though, right? The problem is they are there, they exist, but they're just not rendering after a certain frame.

Just so you know I'm not being stubborn, I tried taking off the particle lifetime and maxed out the particle limit, it just makes a ton more particles in the Layout preview window, but they still don't render. So its not that my particle setup isn't working... unless there is some hidden value somewhere regarding whether or not to display particles?

I've ordered more RAM for my computer as well and it should be here this week (will have 4GB up from 2,) so I'll come back and let you all know if that was the problem. Meanwhile if anyone else has any suggestions, I'm all ears!


10-26-2009, 12:00 PM
Well I think I figured out what may have been the problem, though I am still really confused as to why this would be the case.

My scene has 2 emitters - one that creates a stream of particles pushed by a Wind animation path to enter the chamber, and then one that "trails" the liquid, as described above. It appears as though the first emitter's particle limit was somehow affecting the limit of the second one. Even if I made the limit on the first one really high, however, it still wasn't enough. And going over 2 million crashed the program. So I simply deleted the first emitter and am using the "trail" even for the entrance of the particles to the chamber. It doesn't look exactly right, as they are now too wide to fit through the narrow opening and so they clip through some geometry, but at least they are visible.

Thanks for the help, guys, and if anyone knows exactly why having 2 particle emitters was such a problem feel free to pop in and inform us! I'd sure like to know!

10-31-2009, 02:47 PM
Sounds like a possible shading problem if you can actually see the complete (and correct) animation in Layout but once you render the're gone.

Do you have any envelopes or gradients setup which could cause the visibility of the particles to drop below 0?

There are several parameters which could drop the visibility of the particles to 0:

The HV Dissolve channel (right below the Object Type).

on the Geometry tab:
Particle Size

On the Shading tab:

If one of those has an envelope or a gradient applied to it which drops below 0 then the HV's won't render ofcourse.

Also, if you parent one emitter to another and have that emit particles from the parents particles (parent-emitter) usually the particle count goes up astronomically if you do not pay attention to the parent emitter's Birth Rate but that shouldn't affect the particles visibility at render time.

11-04-2009, 06:28 AM
Your config is not quite clear. In your first message you say that your emitter is parented to a null that has a lifetime of 15 frames (which might explain the unappearance of the particles as you say that they are fixed to start at frame 76 ?)
In your last message you talk about 2 emitters. Parented or not or do you mean the null of your first message was an emitter ?