nigelgardiner Posted July 19, 2016 Share Posted July 19, 2016 Hi There I'm trying to create an art directed splash in a flip fluid and am using an rbd object to make the splash. My results to date are a little rough so I have some questions about my set up. The splash needs to happen in real time. I've created a vdb volume for the the rbd object and am using this as the proxy collision volume. In the Rbd solver should I be using volume or point velocity for collisions? In the Flip object should I be using volume or point velocity for collisions? In the Flip solver under particle motion I have under resolved set to use extrapolated velocity and collision detection as move outside collision. In the Flip solver under volume motion I have collision velocity type set to volume. Is using a vdb volume as collision volume the best approach to this? I've tried keyframing the movement and using the rbd object attached to a static solver I don't seem to see much difference in the results, is this to be expected? I've watched the sidefx tutorials and searched on line but can't seem to find any answers relevant to this. I've seen Igor Zanic's work and many others that have beautiful water collisions so I'm really trying to head in that direction Any answers and advice much appreciated. Thanks Nigel. Quote Link to comment Share on other sites More sharing options...
rbowden Posted July 19, 2016 Share Posted July 19, 2016 Post a file, if you can, of where you are stuck at. You need to also elaborate on how your results look rough. What type of splash are you going for here? Is this a building falling into the water? Is this a crown splash? etc. Unfortunately no magic settings really exist when you are doing these types of fx so, it is good to know what you are after. Quote Link to comment Share on other sites More sharing options...
nigelgardiner Posted July 19, 2016 Author Share Posted July 19, 2016 Thanks Ryan Yeah I figured I have a lot to work on, just want to make sure I'm approaching it the best way to begin with. Here's the hip file of my test run. I'm trying to make a large pool splash which then is to travel across talent standing by a pool, if I can get a decent splash I figure I can force it gently with a curve force or something to travel in the right direction and/or rotate the pool horizontally and cheat gravity in that direction. rbd splash.hipnc Quote Link to comment Share on other sites More sharing options...
rbowden Posted July 19, 2016 Share Posted July 19, 2016 So if I understand this correctly, you want to create a splash and then have that splash, while in the air, attract towards a character that is standing by a pool? Quote Link to comment Share on other sites More sharing options...
nigelgardiner Posted July 19, 2016 Author Share Posted July 19, 2016 Yeah, tall order i know, client has seen Igor zanics whale splashes so that's the reference. splash has to start off small and noisy and then gain volume to cover the lower half to hide a costume change. All while lasting 3 sec in real time and not being slow motion. Quite a big ask. I've got some experience with fluids but I'm struggling here, fun challenge tho. Quote Link to comment Share on other sites More sharing options...
rbowden Posted July 19, 2016 Share Posted July 19, 2016 With Igors whale splash, I don't know the specific setup but, I would assume he isn't adding any additional velocity fields and the shape of the splash is reliant on how the whale is hitting the water. With an effect like this, it is not about settings, alot of it has to do with the collision object that you are using to make the splash. Sure you can pump in velocities and shape it additionally but, the base of the splash still needs to work. You can use vdb volumes for collision on this but, you would be using houdini RBD the whole time. That isn't a bad thing but, it can be a little bit slower. I would try and see if you can get it working with bullet first. You also don't as deep of pool as you have now. I would definitely cut the pool depth by half at the minimum. For creating the splash, it depends on how the splash is going to be created. Is it happening from an object breaching the surface or is it happening from something dropping into the water? If it is something dropping into the water and you aren't doing the animation of the object dropping in, you will most definitely need to fake it with forces. The same goes for breaching if you have no control over the animation. If you have control over what is dropping/breaching, I would definitely create some collision geo that is interesting and could give you the shape that you need. Right now, your tube geo isn't going to give you much as far as an interesting splash and it is coming ridiculously fast out of the water.https://vimeo.com/106930270 http://forums.odforce.net/topic/18454-houdini-flip-explosion/ Give those two links a look of maybe some ideas you can incorporate. Good luck! Quote Link to comment Share on other sites More sharing options...
nigelgardiner Posted July 19, 2016 Author Share Posted July 19, 2016 Thanks Ryan, much appreciated. Yeah collision speed is one thing I know is wrong. So there's no reason not to keyframe the collision object? I mean is it only really the velocity of the object as it collides with the fluid that's being taken into account anyway by the flip solver? And yeah I've got to work on the collider shape for sure. Quote Link to comment Share on other sites More sharing options...
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