Magasul Posted November 17, 2014 Share Posted November 17, 2014 Hi! I am new to Houdini and as a first project I am trying to make a cone + ice cream combo drop, hit the floor and shatter, while the cream melts. I have succesfully created the two effects seperately and then put them together. They interact with eachother but the FLIP fluid of the cream penetrates and leaks the cone. The strange part is if I try it with the non-fractured cone, the fluid doesnt leak (same collision settings). Help me solve why please? (The grid melter object is a small grid that transfers viscosity attribute to the particles, so that it melts faster, the closer it is to the ground.) Thanks! 001_IceCream.rar Quote Link to comment Share on other sites More sharing options...
Magasul Posted November 17, 2014 Author Share Posted November 17, 2014 Also worth mentioning is that I would like the cone to influence the cream and the cream to influence the cone vica-versa, not just simulate the cone shatter and then cache it to make it a collider to the cream. (Bonus: I would also like the ice cream to be glued to the cone as they fall.) Quote Link to comment Share on other sites More sharing options...
kleer001 Posted November 17, 2014 Share Posted November 17, 2014 Can you upload a youtube video of your problem? Also, your scene is a little heavy. Any chance you could do a lightweight proof-of-concept that demonstrates the issue you want to solve? Sorry, just being picky. I'm sure someone with more time can help without those extras I'm asking for. Quote Link to comment Share on other sites More sharing options...
Magasul Posted November 17, 2014 Author Share Posted November 17, 2014 https://www.youtube.com/watch?v=d9ioYpOKOEU&feature=youtu.be As you can see, the icecream (its a fairly good pointcloud, penetrates the fractured+glued rigid cone, but it still has an effect on the icecream. I don't understand. Can you upload a youtube video of your problem? Also, your scene is a little heavy. Any chance you could do a lightweight proof-of-concept that demonstrates the issue you want to solve? Sorry, just being picky. I'm sure someone with more time can help without those extras I'm asking for. Quote Link to comment Share on other sites More sharing options...
kleer001 Posted November 18, 2014 Share Posted November 18, 2014 maybe try manually swapping out the unbroken cone with the glued cone on impact? I would make the cone pieces a bit thicker and lower res also. It does look like you have holes in them somehow. Quote Link to comment Share on other sites More sharing options...
Magasul Posted November 18, 2014 Author Share Posted November 18, 2014 The unbroke cone isn't simulated. I pre-shattered it with the voronoi nodes. I made them really thick (the collision geometry) but it still doesn't help. I upped and lowered the resolution and still it passes through. Odd thing is, with the same resolution, thickness etc. the cream interacts properly and collides with the unshattered cone geometry, but not with the shattered. Difference is that one has fragments. Still clueless. maybe try manually swapping out the unbroken cone with the glued cone on impact? I would make the cone pieces a bit thicker and lower res also. It does look like you have holes in them somehow. Quote Link to comment Share on other sites More sharing options...
rayman Posted November 18, 2014 Share Posted November 18, 2014 Make sure you have checked Connect Inside Pieces on voronoi fracture node. Quote Link to comment Share on other sites More sharing options...
Magasul Posted November 18, 2014 Author Share Posted November 18, 2014 Turned it on, still goes through. Make sure you have checked Connect Inside Pieces on voronoi fracture node. Quote Link to comment Share on other sites More sharing options...
Georgie Posted November 18, 2014 Share Posted November 18, 2014 (edited) never mind, scratch that. Edited November 18, 2014 by Georgie Quote Link to comment Share on other sites More sharing options...
Magasul Posted November 18, 2014 Author Share Posted November 18, 2014 I'm really dumbfunded about why this is happening. It is supposed to work... Quote Link to comment Share on other sites More sharing options...
Georgie Posted November 18, 2014 Share Posted November 18, 2014 well, I can't answer why but I can tell you that the problem is the particles 'slipping' through holes in the volumetric representation of your pieces. If you turn off the volume representation for collisions on the RBD Fractured object everything seems to work just fine. No idea why there are so many holes in the volume tho Quote Link to comment Share on other sites More sharing options...
Magasul Posted November 18, 2014 Author Share Posted November 18, 2014 I turned off "Use Volume Based Collision Detection" but it still slips. As you can see on the image I have no leaks. :\ At least not where it slips through... well, I can't answer why but I can tell you that the problem is the particles 'slipping' through holes in the volumetric representation of your pieces. If you turn off the volume representation for collisions on the RBD Fractured object everything seems to work just fine. No idea why there are so many holes in the volume tho Quote Link to comment Share on other sites More sharing options...
eetu Posted November 18, 2014 Share Posted November 18, 2014 Firstly, you need to look at the collision field of your flip fluid object to be sure there is no holes in the collision. The collision object volume representation is sampled into your simulation collision field - and if your flip sim is in a low resolution then the sim collision field might end up crappy in the sim even though it looks good on the object's collision data. Secondly, and more importantly in this case, even though you have disabled the RBD on your cone object, its initial velocity is still copied to your simulation's collision velocity field. This collision velocity drives your fluid through the collision area. In essence, always check the simulation field visualizations (the Guides tab in your flip object) in case of problems. 1 Quote Link to comment Share on other sites More sharing options...
Magasul Posted November 18, 2014 Author Share Posted November 18, 2014 (edited) Hey eetu! Thanks for the reply! Firstly I tried turning on the collision guide and this is what showed up: I also turned on and set the collision separation to 0.05 but still it leaks. The cone is an active rigid body with an active value set to 0 always. (Sub stepping is 2 on the DOP network, but with 4 it's the same) Firstly, you need to look at the collision field of your flip fluid object to be sure there is no holes in the collision. The collision object volume representation is sampled into your simulation collision field - and if your flip sim is in a low resolution then the sim collision field might end up crappy in the sim even though it looks good on the object's collision data. Secondly, and more importantly in this case, even though you have disabled the RBD on your cone object, its initial velocity is still copied to your simulation's collision velocity field. This collision velocity drives your fluid through the collision area. In essence, always check the simulation field visualizations (the Guides tab in your flip object) in case of problems. Edited November 18, 2014 by Magasul Quote Link to comment Share on other sites More sharing options...
eetu Posted November 18, 2014 Share Posted November 18, 2014 Secondly, and more importantly in this case, even though you have disabled the RBD on your cone object, its initial velocity is still copied to your simulation's collision velocity field. This collision velocity drives your fluid through the collision area. Just zeroing out the initial velocities makes it behave. IceCream_and_Cone_002e.hip 1 Quote Link to comment Share on other sites More sharing options...
Magasul Posted November 18, 2014 Author Share Posted November 18, 2014 (edited) Wow! Nice! Just to make it clear. What did you change? Cause by simply 0-ing out the cone RBD object regular and angular velocities still makes it leak in my scene. Odd thing is, I matched all attributes on the cone RBD DOP, the flipfluidobject DOP and the flipsolver DOP and still it doesn't work on my scene. But if I copy your flip nodes and replace mine with them, all of a sudden they work, even though they are the exact and same. That's why I'm asking exactly what you switched on or off or entered, cause I can't seem to find what's different. *edit* Ok. I found that my merge node wasn't on mutual. That solved it, now it works! Also a question would be that since it has no initial velocity, how would I drop the ice cream. What I'm trying to achieve here is that at the first few seconds, the ice cream should settle in the cone, then both of them drop to the ground. That's what I wanted to achieve with the active value animation. Thanks really in advance! Just zeroing out the initial velocities makes it behave. Edited November 18, 2014 by Magasul Quote Link to comment Share on other sites More sharing options...
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