snow globe

[itriix]

hello everyone. i want to make a snowglobe. i thought it would be cool because i could showcase a few different effects in one. example: the globe itself, having fluid inside, with little objects floating in the fluid. the globe i was thinking to have hanging from a string swinging around eventually smashing into a wall... or just dropping it on the ground and having it shatter. so anyways. you get the picture. so as soon as i began, i ran into a problem. i'm assuming it definately has to do with collisions but here is what happened. when i created a sphere. and i created fluid from object. and then i duplicated that original sphere, and scaled it out a bit so that it would be larger than the fluid. and then i made that globe a rbd object. everything goes wrong. the sim pretty much comes to a hault. and the fluid wants to try and GET outside of the globe. i'm sure there is something basic i'm missing here.

i also tried extruding the snowglobe to help collisions

and also tried turning the extruded snowglobe into sdf with isooffset. when i do this and make it an rbd, the fluid just passes right through the sdf volume

please any help would be fantastic.

to sum up:

i want an animatable sphere with fluid inside

thanks so much,

J

Edited June 7, 2009 by itriix

[aracid]

hey itriix

the key is, to make any rbd,fluid or dop react to something inside a volume is to invert the sdf,

taken from : http://www.sidefx.com/docs/houdini10.0/nodes/dop/rbdobject

"If you want a hollow box, one method is to build one box inside the other and not use Laser Scanning. A more robust method is to just specify the inner box and use sign inversion. This treats everything outside of the box as inside, allowing the more robust Laser Scanning method to be used."

so you dont need two objects to create the collision boundry, ie one inside the other, but rather using the invert feature, then everything will remain within the object.

hope this helps

[itriix]

so you dont need two objects to create the collision boundry, ie one inside the other, but rather using the invert feature, then everything will remain within the object.

hope this helps

hey aracid, thanks for the reply. i tried what u mentioned but the fluid still just seems to pass right through the sphere as if the sphere was not there.

here are my steps:

created sphere, create fluid from sphere, duplicate sphere, scale duplicate sphere - this will be the actual snowglobe. then inside the snowglobe obj, i used an isooffset, set to sdf volume, i tried inverting and not inverting. i go back to obj level. select the snowglobe - then make it into an rbd obj. everything is set up in autodop. i try to play. the fluid passes right through the sphere. so i tried, inverting in the isooffset. this didn't change anything. i tried setting the MERGE node inside of the autodop, to LEFT inputs Affect Right Inputs. That didn't work either. hmmmm

i'm missing something here....

***EDIT***

fixed it. was trying to turn the globe itself into an sdf, and then inside dops, using volume collision and inverting sign. i just needed to delete the isooffset

Edited June 8, 2009 by itriix