Pancho Posted October 6, 2015 Share Posted October 6, 2015 I'm doing fine so far with the magnet force. Assign it to a metaball, activate it via an expression and on the specified from everything is shattered. So, that's one force. But imagine I have 20-50 fractured objects and I want to blow them up with a force more or less in the center of each object. How would I do that? I could use particles for spawning objects and forces, but even if there would be one metaball inside of each object, how would I activate the foreces randomly or on slightly offset frames? Is magnet force the way to go and if yes, how to activate the forces independently/proceduraly? Cheersand thanks in advance! Tom Quote Link to comment Share on other sites More sharing options...
Pancho Posted October 8, 2015 Author Share Posted October 8, 2015 A hundred views and no ideas or tips? O.k., I make it a bit easier: Is there an alternative to the magnet force which can be used for RBDs? Can I assign a magnet force to points/particles and scale the force by the particle size or color? Like I said, there are many rbd objects which need to explode slightly offset/randomly. Cheers Tom Quote Link to comment Share on other sites More sharing options...
Farmfield Posted October 8, 2015 Share Posted October 8, 2015 (edited) I think you haven't got answers because your initial solution seems as personal as any I've seen, not uncommon in the Houdini forums, so if I read that and it's not the way I'd go, if I want to answer, I gotta start figuring out what you are doing and why - which sometimes is interesting, but often not, hehe... In this case I'm not going to bother about what you are doing and why but present how I'd do it - and I'd use point clouds, because I've done that, set it up, and not only does it work well, it's so immensely "directable", you really have full control over everything from timing to how your stuff explodes, in what direction, etc... And to set this up for multiple objects in one go, just create your point cloud velocities, then set it up with a VOP in a SOP solver inside your DOP's, merge in your velocities and use switches to control when you want the velocities to act on your objects. Controllable and very directable, as you can sculpt the velocities... Demo and scene file here: www.vimeo.com/115202251 Edited October 8, 2015 by Farmfield 1 Quote Link to comment Share on other sites More sharing options...
Pancho Posted October 8, 2015 Author Share Posted October 8, 2015 Vop in a Sop in a Dop? I guess I need mental treatment. This makes me fuzzy! Well, your explanation and video seem to shed a bit more light. First of all, to give you a better idea: One nice voronoi example is to blow up columns, usually antic ones. If you you think of the Pantheon, there are quite a few of them. For what ever reason some maniac wants to blow up these columns. Since there are many, using the Metaball/Magnet Force is a no go. Since they should explode randomly, I guess a point cloud with the explosion centers would be a good start. But probably I think too much about blowing up stuff and not about what's happening under the hood. I guess you want to tell me that blowing up stuff is just a velocity force transfer from point (or mesh) to my RBD objects. I can't look at your scene right now, but is the Dop Network just working in this manner in your file? That a switch is enabling the force? Hope your scene gives me an idea how to do that for multiple points? In SI I probably would have an array with booleans to check if the column explosion is enabled and another array when this happened. So SI could check for how many frames the force has been enabled. I guess after 2-4 frames the force could be switched of. Repeat nodes in SI are in general a bad thing to do. What about H? Would you handle each explosion in a for each node? one could check on each frame whether the explosionStartFrame attribute matches the current frame. If this is the case transfer, the velocity (attribute transfer?)? In terms of ideas how to solve stuff, I'm not so bad, but coming from SI and "working" with H for only a short time, i'm not so good at "writing" it down with nodes, or even worse, with vex code. Hope your example will give an answer to most of my questions. Thanks in advance! Tom Quote Link to comment Share on other sites More sharing options...
Farmfield Posted October 8, 2015 Share Posted October 8, 2015 (edited) Hehe, this is the life in Houdini, at least so far we have no need for COP's or CHOP's though you probably need to use SHOP's and ROP's further down the line... But about how I would set it up - breakdown in four steps. 1. Create your model, pre-fracture it and add constraints to the point your model keeps together. (SOP's) 2. Now you create point clouds with directional/velocity values placed in the scene, where you want the explosions to happen. (VOP's in SOP's) 3. Play the sim and it'll just "be", hang on it's own weight, supported by the constraints. (DOP's) 4. Feed the velocity values onto the fracture pieces, you can use expressions or you can use switches (SOP solver in DOP's) Boom. Edit: I also left SI. In 1999. Last version I worked in was 3.8... I am an ancient creature. Edited October 8, 2015 by Farmfield Quote Link to comment Share on other sites More sharing options...
anim Posted October 9, 2015 Share Posted October 9, 2015 (edited) ... Since there are many, using the Metaball/Magnet Force is a no go. ... that's exactly the way to go, or one of them you can simply create pointcloud copy metaballs on and randomly be turning them on and off based on frame and some duration then just keep only active every frame so that your Magnet force gets different metaballs each frame therefore will be producing random explosions but since hipfile is worth 1000 words, here it is: I used POP Metaball Force instead of Magnet Force, but they work the same way so the important step (SOP level setup) is the same ts_random_explosions_metabal_force.hip Edited October 9, 2015 by anim 3 Quote Link to comment Share on other sites More sharing options...
Diego A Grimaldi Posted October 9, 2015 Share Posted October 9, 2015 Love the gif, Tomas Quote Link to comment Share on other sites More sharing options...
Pancho Posted October 9, 2015 Author Share Posted October 9, 2015 Thanks for all the input! Will disect your file as soon as I can get hands on Houdini back in the office! Cheers Tom Quote Link to comment Share on other sites More sharing options...
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