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Wire-Solver: Falling fir-branch - Attache wires to another wire-object

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I tried the latice + deltaMush approach and it works! It is still not perfect, but like petz says, this seems the best method if you have wires that do not match your highres mesh 100%. I don't think this is the way to go when you can decide from scratch how the setup will be, but it is a good way if you are somehow locked in on which model and wires you have to use. Thanks alot for this petz! 

I will now try to adapt my setup to use the simulated wires as base of the actual highres model. This method has none of the problems from above, and I think, this is the best way to do it for my case.

Further updates will follow :) Thanks guys!

 

 

firBranchWireSim_latticeDeltaMushDeform_v001.hipnc

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First test for the wire-setup is here. The sim works, the highres is based on the sim-curves, so it moves along without any problems.

What I have difficulties with at the moment is sim-scale. The branch itself is 10units long. When I sim with standard settings (1unit=1m), the sim works out fine, but looks slow motion, because the branch,is actually 10m in size. When I set my scale more towards realworld scale (1 unit = 0.01m = 1cm), the sim goes crazy. I have to do enormous substepping, to compensate, resulting in very long sim times. And the wire-settings (parameters) need to be tweaked all over again. (sim-settings are corrected for the scale -> gravity at 981, solver spatial scale at 0.01). It only works with standard substepping values when I "film it in slow-motion", meaning to crank up the scene-frame rate to about 250fps like you would when filming this for real with a camera. After that, you could save a cache and retime that cache to realworld speed. But I am not sure if this is how you do it. What would you guys say is the best way to approach this?

I attached my latest file for you to play with. (1unit = 1m version).

Cheers!

firBranch_wireSim_v002.hipnc

Edited by Scratch

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Update:

The only way I could get the simulation (branch falling fom 5cm down to ground) to work under real world scale conditions (1unit = 1cm) was as described above, by increasing the scene frame rate (to e.g. 250) and "filming the falling branch in slow motion" like you would when shooting this in slow-motion for real. This has the advantage that the movement - which takes place in less than a second -  can be simulated accurately without the need for heavy substepping.

I can not cache it with Houdini's Apprentice, but if I'd be able to, I'd cache the sim-results out in slow-motion (bgeo files), and then retime the geo-cache to whatever speed I like it to be for the final. I am not sure if this is the right way to do it, but it seems to be a way that works. (The file I worked with today is attached.) Playblasts and breakdowns will hopefully follow during the week :)

One question regarding substepping emerged during the tests today: When do I need to increase substeps on the entire DOP-Net, and when is it enough to just increase it on the particular solver?

Cheers!

 

firBranch_wireSim_v003.hipnc

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Changed the Settings to cm so 1 unit is 0.01m, solver spatial scale results in 0.01 / gravity is -981, density 0.001, Dopnet-timescale 0.1 (for slowmotion look) and around 8 substeps on the wiresolver. Should have the same effect than scaling the Geo down by a factor of 100 (m->cm) without touching gravity, density and spatial scale. Siming it in realtime (timescale=1) also worked, but needed a pretty high substep amount of around 50 on the wiresolver to get good results. But that seems to be right aswell, since timescale of 0.1 is like having 10 substeps, and I am substepping this some further 8 times on the wiresolver (10x8=80 in total). So having 50 steps for realtime seems to be ok. Thats how it made sense to me, and I am really happy with the results so far :)

 

Edited by Scratch

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while this can be done - DO NOT DO IT.

scale your geometry instead - Houdini will work better and there will be less confusion.

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Right, will definitely try it for the next project! Thanks, and thanks again to all that helped me along the way!! :)

Edited by Scratch

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