Aronstone Posted April 15, 2022 Share Posted April 15, 2022 Hi guys, I am trying to emit color smoke from a shell. I thought a good particle emission will help with the volume source from which I can emit my pyro. But, I am currently stuck at one stage where I am unable to get a nice and smooth particle flow. A lot of stepping!! I've attached the images, the effect I am trying to achieve (for reference) and also the hip file. It might seem like a simple solution to someone out there. Please struck me with some knowledge! Thanks!! Color smoke ref.mp4 Color_Smoke.v68.hipnc Quote Link to comment Share on other sites More sharing options...
Sepu Posted April 15, 2022 Share Posted April 15, 2022 I highly recommend watching this so you understand and he shares some nice tricks. Quote Link to comment Share on other sites More sharing options...
Atom Posted April 15, 2022 Share Posted April 15, 2022 That is an informative talk, but after following the steps I can't see any difference. I have modified the OP's hip file, but the gaps remain. The simple solution is substeps followed up with a light pointjitter, but I really don't like adding substeps to a simulation. ap_Color_Smoke.v68.hipnc Quote Link to comment Share on other sites More sharing options...
Aronstone Posted April 16, 2022 Author Share Posted April 16, 2022 Thank you so much for the link @Sepu. And Thank you so much for your time and hip file @Atom. It was great help checking the file while watching the video. I had to watch it multiple times as a lot of terms just flew over my head. It's a superb approach. But, as stated by Atom, It's not giving me the exact flow which I am looking for. Especially during the ground interaction, it completely breaks down. I'll try with substeps and point jitter but I guess it's gonna be costly. Do you think I can slow down the whole simulation so that we can have ample amount of time for particles to react? And any thoughts of using external forces(pop curve...)? Thanks again for timely response. Quote Link to comment Share on other sites More sharing options...
jacksper Posted April 16, 2022 Share Posted April 16, 2022 (edited) Hello Prasanth, I had made some changes in the emitter and the pop sim and its works well for me 1) i changed the sphere into a semisphere (in reality its like a sprayer so i used semisphere as one side emitter) 2) created a vel using the semisphere 3)jitter birth time to positive and interpolation method to match topology (**** highly recommend you to use match topology when the geometry points and the emitter points before sim are same ******) and added some variance in velocity i hope it might help for you, if you have any doubts please reach me out Have a nice Day ap_Color_Smoke_nagoor_version.hipnc Edited April 16, 2022 by jacksper 1 Quote Link to comment Share on other sites More sharing options...
Follyx Posted April 16, 2022 Share Posted April 16, 2022 Lot of tuts online. I.e:. https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjj-LXCo5j3AhWYRPEDHYJ8CesQtwJ6BAgGEAI&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3Dw0eGwlGyTjE&usg=AOvVaw2Mb6kBuuYNbW8BSCJjfmGZ https://www.cgcircuit.com/tutorial/how-to-fix-particle-stepping-in-houdini?utm_source=youtube&utm_medium=social&utm_campaign=how-to-fix-particle-stepping-in-houdini https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjj-LXCo5j3AhWYRPEDHYJ8CesQtwJ6BAgQEAI&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DriUx1ILoedc&usg=AOvVaw1kdearygh3nJWPunWjhFHX Was just the first three after a google for "Houdini particle stepping". I am sure you will find a lot more online. Also try to change your popsetup before changing the subseps. 2 Quote Link to comment Share on other sites More sharing options...
Aronstone Posted April 16, 2022 Author Share Posted April 16, 2022 Thanks for the links @Follyx. The issue rises only when I'm trying to collide with the shell I have. Without the collision, the particle doesn't have any stepping issue even with single substep. I've used the lerp method many times. But in this case, it just gonna ignore the collisions. I guess I need to ignore collisions for this one. As the motion is happening so fast, maybe I can get away with it or I can simply kill those particles which are colliding using pop collision detect. That seems to be working. Thanks again for your time. I'll try to find more resources. Quote Link to comment Share on other sites More sharing options...
Atom Posted April 16, 2022 Share Posted April 16, 2022 (edited) The lerp approach does work, but it adds a lot of noise to the system. As you discovered, modifying points after the simulation can lead to a collision artifacts. There was a mention in the Luma Pictures video about modifying velocity before it enters the popnet. I noticed your setup is multiplying velocity by 5 inside the popnet. Try returning inherit velocity back to the default of 1 and multiply velocity by 5 before entering the popnet. This may improve collision results and require less post-sim fixup. Edited April 16, 2022 by Atom 1 Quote Link to comment Share on other sites More sharing options...
Aronstone Posted April 21, 2022 Author Share Posted April 21, 2022 Thanks for the hip file @jacksper. Sorry that I couldn't respond quickly. Just saw the reply. I guess it's only for higher input velocities. when the velocity is not enough, the collision is taking over and I am ending up with the same artifacted result. I've ended up ignoring the collisions, placing the emitter a bit outside the shell. It seems to be working just fine. Thanks again for you time! 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.