Dee Posted April 29, 2009 Share Posted April 29, 2009 Hi all! I have a bunch of little debris pieces that I want to instance onto points. I have the instancing setup complete and have the fluid sim working. You can do it with a very high viscosity liquid. That way it looks like sand or jello when the character interacts with it. I want to instance the objects onto the fluid sim points. When I do that, the rotations go insane! I can view the normals and see them flipping all over the place. Is there a way to setup some --sane-- rotations in a fluid sim? I know it's not the normal way to do it, but is there? Or is there a way to fake the rotations somehow? I just need the character to be able to push them aside and have the debris parts wiggle and then settle in a new rotation to match the movement. Does that make sense and does anyone know how? ~Dee Quote Link to comment Share on other sites More sharing options...
Dee Posted April 30, 2009 Author Share Posted April 30, 2009 So I tried using orientation nodes in dops and rotation nodes. I tried orienting to the normal, but no luck. The normal flips too much. The orientation and rotation nodes don't ever seem to make an attribute I can use. Perhaps I'm doing them wrong or something. ~Dee Hi all!I have a bunch of little debris pieces that I want to instance onto points. I have the instancing setup complete and have the fluid sim working. You can do it with a very high viscosity liquid. That way it looks like sand or jello when the character interacts with it. I want to instance the objects onto the fluid sim points. When I do that, the rotations go insane! I can view the normals and see them flipping all over the place. Is there a way to setup some --sane-- rotations in a fluid sim? I know it's not the normal way to do it, but is there? Or is there a way to fake the rotations somehow? I just need the character to be able to push them aside and have the debris parts wiggle and then settle in a new rotation to match the movement. Does that make sense and does anyone know how? ~Dee Quote Link to comment Share on other sites More sharing options...
pclaes Posted May 1, 2009 Share Posted May 1, 2009 errr... tricky. I did something similar for the pieces of fruit inside my jam. I think I just manually defined some random normals in the end though. For you however the tricky part is the correct movement in the direction the character is going. If nothing else I would try to hack it by giving the points a bunch of random vectors and at a later frame define other random vectors and blend between the two. You can use attribute transfer and a sop solver to get a mask that sticks to the points - I don't know how wild your sim is. You can trigger the rotation values of the points based on the distance they travelled between your start frame and end frame. For slightly less random vectors you could do a quick 2d simulation, bring it into sops and attributetransfer the x and z vectors to the points. I've attached a hacked together file - I wouldn't call it a solution though - but perhaps it can give you some ideas. rotation_transfer_02.hipnc Quote Link to comment Share on other sites More sharing options...
brianburke Posted May 3, 2009 Share Posted May 3, 2009 Not sure if you've already gone down this route, but you could perhaps use vorticle geomety as your instance template and use the gas velocity stretch node to give you sensible rotations. http://www.sidefx.com/docs/houdini10.0/nod...velocitystretch Quote Link to comment Share on other sites More sharing options...
spev Posted May 3, 2009 Share Posted May 3, 2009 try embedding particles into the fluid using the shelf tool You will then have lots of particles to do stuff with Quote Link to comment Share on other sites More sharing options...
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