JaydenDP Posted March 9, 2013 Share Posted March 9, 2013 Hi guys! I'm trying a couple things to do some particle multiplication for a FLIP simulation. I'll propably just end up running a few rendertime cvex noises on a delayed load FLIP cache, but I also wanted to try resim some particles based on the FLIP simulation so that I could maybe write out a bunch of pop sims with different seeds and read those back in a delayed load and try rendertime multiplication like that. One thought was to use a VOPPOP and "inherit" the velocity from the FLIP sim onto the particles, it almost works but not quite... Any ideas what I'm doing wrong? or if anyone can think of another way, any help would be much appreciated! There's a simple test scene attached if you want to see how the VOPPOP isnt quite working ;P Thanks in advance. Jay particleFluid_VOPPOP_test.hipnc Quote Link to comment Share on other sites More sharing options...
CeeGee Posted March 9, 2013 Share Posted March 9, 2013 Hi, Maybe you can try advectByvolumes in popnet, using flip vel field. particleFluid_VOPPOP_v002.hipnc preview.mov 1 Quote Link to comment Share on other sites More sharing options...
JaydenDP Posted March 10, 2013 Author Share Posted March 10, 2013 Yeah thanks man, thats a lot better! I thought about using advection for a few seconds and then for some reason thought it wasn't going to work... I'll have a go with this then and try it on my shot, might give me what im after. And now, just out of interest, why would'nt the pc lookup velocity work the way I expect it? It seemed to almost work...anyway, more out of curiousity at this point. Thanks again, Jay Quote Link to comment Share on other sites More sharing options...
JaydenDP Posted March 10, 2013 Author Share Posted March 10, 2013 It actually works quite well... Attached 2 quicktimes, one is the FLIP simulation and the other is the advected particles based on that sim. Jay FLIP_ONLY.mov FLIP_with_POP_MULTIPLIER.mov Quote Link to comment Share on other sites More sharing options...
CeeGee Posted March 10, 2013 Share Posted March 10, 2013 Yes work realy nice, and also its fast for simulation. Maybe you can add more viscosity and also noise on viscosity, maybe this can look like sand then. Quote Link to comment Share on other sites More sharing options...
JaydenDP Posted March 10, 2013 Author Share Posted March 10, 2013 Yes work realy nice, and also its fast for simulation. Maybe you can add more viscosity and also noise on viscosity, maybe this can look like sand then. Yeah my sim at work has variable viscosity, and sells the sand look quite well. Was just messing around at home with this quick sim to figure out my rendering problems before I get back in tomorrow. Quote Link to comment Share on other sites More sharing options...
CeeGee Posted March 10, 2013 Share Posted March 10, 2013 I was using this workflow for flip waterfall, just to upres main flip sim, so for example main sim was 5h - 10mil particles, and this upres workflow 13mil - 20min. Also good thing is that you can generate normals on this particles from main sim, and use for spec and reflection if you need. Quote Link to comment Share on other sites More sharing options...
JaydenDP Posted March 10, 2013 Author Share Posted March 10, 2013 Ooo yeah, thats a good point. I'll definitely be doing that too then! Thanks ;P Quote Link to comment Share on other sites More sharing options...
johner Posted March 10, 2013 Share Posted March 10, 2013 (edited) Here's an approach that uses DOPs for a particle multiplication effect. The advantages to doing it in DOPs are: - the GasAdvect DOP is faster and more accurate than the AdvectByVolumes POP - handle collisions roughly the way FLIP does - support emitters - support closed tanks - staying in DOPs is faster than doing anything into POPs In general it should take longer to draw the results of this setup than to "solve" it. This uses the lo-res surface field to stop too many particles coming from the emitters, just as it works in the lo-res sim, but it's not really accurate enough at hi-res. You can turn off Kill Inside on the emitter if you'd rather just have tons of particles (which is kind of the point, right?) Also, it might be worth setting the Collisions Separation smaller (like equal to the Particle Sep) for the lo-res sim, so you can provide the upres-ed sim a better collision field. Edit: one more thing, it can be useful to turn the FLIP Solver substeps down to 1, then substep at the DOPNet level on both the lo-res and hi-res DOPNets. This just lets them both substep for better accuracy. upres_advect_dops.hip Edited March 10, 2013 by johner 4 Quote Link to comment Share on other sites More sharing options...
JaydenDP Posted March 10, 2013 Author Share Posted March 10, 2013 Ah yeah thanks John. I did wonder whether doing it all in dops was an option too. The point is definitely to throw as many particles at this as possible. I'll take a look at your file when I get in in the morning. Jay Quote Link to comment Share on other sites More sharing options...
vbk!!! Posted March 26, 2013 Share Posted March 26, 2013 ... good thing is that you can generate normals on this particles from main sim, and use for spec and reflection if you need. hmm ... maybe it's a newb question but how can you get spec and reflection on point ? Quote Link to comment Share on other sites More sharing options...
JaydenDP Posted March 27, 2013 Author Share Posted March 27, 2013 Hi Guys, So I'm back onto this now. I'm moving ahead with the POPNET multiplier for the time being. Running into some issues though, Igor maybe you could shed some light on this? For the past few sims i've been doing I cant get the advected particles to match the FLIP particles in terms of "volume", seems something is leaking in the advect by volume step? the particles just keep sinking. Any help with this whould be greatly appreciated. Unfortunately I cant include the HIP at the moment but I've attached a .mov to demonstrate. FLIP is blue Advected POP is white Thanks in a advance... Jay FLIP_POP_ADVECT.mov Quote Link to comment Share on other sites More sharing options...
JaydenDP Posted March 27, 2013 Author Share Posted March 27, 2013 Hi Guys, So I'm back onto this now. I'm moving ahead with the POPNET multiplier for the time being. Running into some issues though, Igor maybe you could shed some light on this? For the past few sims i've been doing I cant get the advected particles to match the FLIP particles in terms of "volume", seems something is leaking in the advect by volume step? the particles just keep sinking. Any help with this whould be greatly appreciated. Unfortunately I cant include the HIP at the moment but I've attached a .mov to demonstrate. FLIP is blue Advected POP is white Thanks in a advance... Jay This happens with the DOP method as well it seems. Guess there's something else going wrong here on my end. Will need to investigate. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.