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anthonymcgrath

transform pieces not behaving and neither is the dopimport trick for low res sim to high res sim

so I have a scene -a character running through some simple walls - that was all setup fairly easily and seems to work sweet.  But i want to transform some high resolution pieces by the low res ones.

there is of course the transformpieces trick but all that happens is my pieces get shifted over from their original position as if re-centred and then the pieces seem to inherit some sort of double-transform or move much faster than the original low res sim.

I tried this tutorial below as well and the same result occurs.

can anyone help here its winding me up - I'm doing something wrong but i've followed a few tutorials and read the help docs on these nodes and it seems i'm doing whats needed :(

cheers
ant


 

 

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Hi again ant!

 check this out

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Maybe your name attribute is not matching correctly...

Make sure you have made the output prefix in the voronoi/assemble unique to each part..

Or you will have pieces that have the same name attribute and transformpieces will be confused

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@derjcmp cheers Jaou i've watched that about ten times in the past lol!

 

@Yon Anadeyo i'll check that out in a bit thanks it might be something as daft as that.  i'm always a little confused with the name attribute simply because one or two sops have it- i'm sure the voronoi fracture does in there seomwhere so i'm not sure if i'm creating a 2nd with the assemble or replacing the old one .

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at wits end with this now - attached a scene file - dont know why the sodding thing doesn't just work when everyone on tuts is like "oh just drop this in and it does it"  it bloody well doesn't :(

building_collapse_v001.hip

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Hey Anthony, there's really only one thing you need to pay attention to and that's the name. It's using the name that the sop manages to transfer from and the low geo to the high geo. That means necessarily you need to have the same names in both of them. If you check your hip, you'll see that your high res geo doesn't have any name, let alone the correct naming.

Another problem is that because the voronoi isn't outputting the same geo, so the naming becomes wonky. If you isolate like the piece12 from the sim and the one from the high res version, you'll they are different pieces, that's a no go. They need to be same

I think the easiest way to fix this is to do only one voronoi, break it and then edit as you want, be making it a high res version or making a low res version. That way you'll guarantee the names are all the same

Alternatively, you can use the new "RBD Sphere Objects" from the shelf in your high res geo and it will create a low res version for you with the naming already sorted out. If you gonna do this manually, pay attention to the collision you're getting inside dops, you need to check "use compound objects" or something of the sort in the rbdpacked dop

 

 

 

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Here you go mate. As vtrvtr says above it's way easier to just worry about your high res gubbins after the voronoi and the name creation, that way all your pieces match up down stream and transform pieces is happy. Only thing I'd say is that although transform pieces doesn't seem to have an issue with it, might be worth refusing your high res chunks back together - You can see from the exploded view that the external and internal geo becomes separated. 

 

 

building_collapse_v002.hip

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hey guys thanks for taking a look sorry i haven't had chance to look at it sooner till now - i've been away all week at home from London (working on animation on Thor Ragnarok at Framestore) so not had much chance... came home for a rest... just chased the 5 year old around (to be fair tho he LOVES playing with houdini... proud dad lol!)


so i FINALLY found the tutorial i was looking at.  heres the prob - this setup requires me to do a voronoi fracture in between the restore_init_pos wrangle... this seems to work and create jagged edged chunks that i can control nicely.

however i cant seem to get that to work via the above file supplied by @adrianr  - building_collapse_v002.hip  - it transfers the anim to the pieces ok and that works ace.. but i've lost the pre-fracture jaggy edges now :/

I tried adding another assemble node but it doesn't seem to work.  And i couldn't suss out how to get a sort node to help me out :/

I've included a scene file - the nodes in question are marked red with a red sticky!

 

building_collapse_v003.hip

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Ahh bugger sorry chap I thought I'd covered that already. Rushed it out on a Friday between usual tasks - Lemme have another look. 

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38 minutes ago, adrianr said:

Ahh bugger sorry chap I thought I'd covered that already. Rushed it out on a Friday between usual tasks - Lemme have another look. 

no prob it makes sense what you did passing the low res chunks into the hi res but i couldn't get that pre-fracture distortion to 'stick' as such

I think what was also confusing is that when i created another voronoi frac with the same settings and an assemble i would have expected the exact same pieces which i do get but its like theres a different value for chunks in the low res frac and another value in the hi res ...even tho they are effectively the same fracture!  weird.

cheers for taking a loook tho much appreciated!

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Yeah you're really creating a headache for yourself with two voronois. Even feeding them the same fracture points doesn't guarantee the same output because you're feeding it a different mesh. 

Regarding this specific scene I have 2 quick solutions. One is doing an attribute transfer after packing the geometry, then unpacking it in the high res stream to do your inner noise stuff. Reason I pack is because then you're transferring the names by proximity from the center of each chunk, so it's way safer than trying to do each chunk where it rests (check the add sop). This does highlight the problem with the two voronois though, as even with the same fracture points the eventual chunk count doesn't match. Fortunately it just seems to ignore it but it doesn't feel very clean. Second, if you were happy with the edge wobble you're getting from that level of divide it's not *too* bad keeping that on your sim geo and chucking it in. Yes your collision geo will be a bit less accurate and it's a few more points but maybe that's ok for you. If it sims stable then it's no worse than the non-collisions you would get transferring the low res sim to the high res chunks anyway. v004 and v005 scenes attached. 

In my opinion I'd look at another route. If you wanted big chunks but with more detail along the edges I'd fracture into smaller pieces and then use clustering with glue constraints to hold those big chunks together. This has the added benefit of allowing secondary breakups when things hit the floor etc. You can then still do the high res stream and add detail to those chunks for even more detail, you can sub-fracture even smaller chunks, or create some displacement vectors to use in a shader for crazy pixel level detail. You get good collisions back too because even with all the edge jagginess to bullet it's still all convex hulls. 

building_collapse_v004.hip

building_collapse_v005.hip

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