Hello, I have a particle system that has the role of debris. I also have 5 objects that represent small fragments. What I'm looking for is a way to instance those 5 objects randomly on to the particle system. Plus on collisions the particles system should react based on the instance shape.
adrianlazar Plus on collisions the particles system should react based on the instance shape.
I haven't figured that part out but you can use switch sop with copy/stamping to randomize the instancing.I would love to know the collisions part though.
I did something like that using RBD Fractured Object. You use the group mask to identify the different debris (which you must have previously grouped in the SOP context) and then you can use the Point Position Node to copy the debris pieces from the RBD Fractured Object onto a particle system. Once that's done you just have to add an RBD Keyframe Active to switch from the particle animation to DOPs simulation and the debris pieces will retain the velocity at the point they were switched and all should become physics simulation from then on. It takes a bit of figuring-out, but can be done! Like Tony Stark said: once you eliminate the impossible, whatever remains, however improbable, must be the answer"… or was it Sherlock Holmes? They look so much alike!
can you please post an example file, Im lost as I am trying to achieve what you described, or if you can decribed in more details the connections between the pops and dops.
Can you please post an example file, Im lost as I am trying to achieve what you described, or if you can decribed in more details the connections between the pops and dops.
Houdini ships with a number of examples that show you how to get pops into DOPs and attach geometry.
I like the procedural way you create the debris instance geometry. Do you think that if I am gonna put that process in a foreach sop and use rand() on the jitter seed, can I get uniqe geometry for each debri?
of course this possible! But not necessary if you ask me. Debris is usually fast, tiny and with the added motion blur you will never be able to tell if some of the pieces have the same geometry, especially because they're all rotating differently. What I'd do is have like 30 different pieces for the instancing and then stamp different scale values on the pieces, that way you get some variation in size.
My shots are in slow motion which does not give much of motion blur. But on the other hand, there are dust. I guess you are right, there is no need for that.
