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About Wolrajh

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  1. THanks, I redid it entirely. Probably not a good idea to post under the effects of frustration and COVID vaccine. To be fair the first question was only a few lines into the post, but I definitely put too much context and pictures.
  2. Hello good people! So I have a few questions about VDB, mostly about things that I never cared about - until I had to. - Why are there translations on the fields of a VDB ? Most render engines do not seem to care, except for Vray. Vray apparently requires all those translatations to be the same for some reason - or else it will generate huge bounding boxes in Maya, and maybe even wrongly sample velocity. Resampling fields will "freeze" those transformations but I never had to do it with Arnold, RS, 3delight or Mantra. For extra giggle, putting a simple point wrangle with @P=0 apparently emulates how Vray see things. - Why can't I get rid of the "dopobject" and Cd attributes when saving to file ? The dopobject attribute is only added when importing the fields with a dopimport fields and not with an object merge. But with the dopimport it just keeps coming back from god knows where, and it makes no sense. - With Vray, am I stuck with having to use the same voxel size for all fields, including Vel, which can in turn creater HUGE files ? Doc indicates Vray can't handle vector fields and I can drop a vdb vector split, but there is nothing about voxel size. I have to accumulate tons of tricks to try and lower the file size. A 250mb VDB file with vel resampled to twice the voxel size can turn into a 1gb file with vel at the original voxel size - and because of how vray handles preview in the viewport, this is unbearable. Alternative is throwing the volume quality through the window to try and hope to reduce file size. I'll include a simple scene file with a few scenarios and oddities which just illustrate those quirks. As I said I usually have no issues but complaints from the Maya Vray departement upon long loading/refresh times ( even for mere 250mb files ) or motion blur not working forced me to approach things very differently... VDB_savingToFile.hip
  3. Custom AOV with V-Ray ?

    Pretty sure I don't have these AOV slots at work either, though I can't be sure we've got the latest version deployed ( I was assured so, but you know how ITs can be ). I'm curious...
  4. Hello there, So I'm back on a V-ray project, and I have to scatter a few impact-like VDBs. I was thinking of going the traditionnal way, getting the point cloud, adding instancepath / instancefile, with a made up string including the much needed offset. Classic, right ? My issue is that I just can't get it to work with vray. It just renders nothing with no relevant info in the log - except "render's done". I tried with VDB files. I tried with vrscene files, tweaking the anim_start primintrinsic. I tried with copystamp and timeshift. I even tried by linking a geo diretly into the relevant instance field. Best I could get to render was instancing the same frame on all points. Instancepath and/or timeoffset look dead in the water. With no access to their own forums, I'm forced to come here to ask : How the heck are we supposed to instance from disk files or create a cloud of timeoffseted instances with Vray ? And all of this despite the V-ray beta 1 release notes stating this :
  5. Hello guys So I have this little bump in the road : I'm emitting vellum instances from a surface. Orient, pos, and various attributes like v work OK, but I can't find the correct way to inject pscale. What happens is that the instanced geometry first appear (p)scaled like expected, but it expands back to the original size after a few frames. My guess is that either restlength or restscale aren't affected by pscale hence the expanding back behaviour, so the question is : how should I proceed ? Can I somehow edit restlength on creation but before solve ? Should I do something else entirely ? Thanks ! vellumPscale.hip
  6. Custom AOV with V-Ray ?

    Thanks for that! Unfortunately my trial now expired so I can't go and test anymore :/ Maybe I will ask the company to grab the Houdini plugin one of these days. Sure sounds weird nobody asked during the beta, IMHO AoVs are a pretty big thing when doing rendering ! Guess you're from the dev team then ? Well thanks for taking the time to come back here, it's really appreciated. Don't let those marketing guys get in the way though
  7. Custom AOV with V-Ray ?

    Yeah, just saw a topic asking for exactly that on their forums. I swear it wasn't there when I decided to ask here myself ( since I can't post over there, weird, weird rules, Chaosgroup ! ) So basically what should be a very basic feature isn't really available yet - the op/: path method is a workaround but it's not convenient at all to say the least Kinda screw up my project, looks like I'll have to make an emergency landing on Arnold's highway :/ Thanks anyway !
  8. Custom AOV with V-Ray ?

    A brief talk with a friend and colleague hinted that I was maybe not using the right words. Best to illustrate I guess : funny enough, the friend told me it's super easy in Maya : just blend all branches from all shaders into one extraTex \o/ Well, I have no idea how to do that in Houdini for once ( add an output to the material container ? then at the root of /MAT/ blend all the new output and plug it into an extraTex ? Still, how do I bring that to the list of render channels ? It's very painful with 40+ materials, isn't it ? ) ... Why can't it just automatically pick up that I added a "pattern" output intended to be rendered into a separate AOV just like the other renderers?
  9. Custom AOV with V-Ray ?

    Would you put that into the shader ? It doesn't seem to acknowledge the render channel in the VFB when I do so... On the other hand, putting it into the Render Element Network generated by the ROP prevents us from linking it to branches of shaders, with the intended purpose obivously being to reproduce the behaviour of the other renderer : export result of a portion of the shader to parameter / render parameter as AOV Of course, I lost contact with my computer and I can't manipulate remotely to test and check some more...
  10. Hey people, Quick and simple question : anyone figured out how to setup and render a custom aov / render channel in Vray for Houdini ? I've been trying things but I can't for the life of me find how to do it. I'm beginning to think it's just not possible, and that would spell doom for the renderer which is otherwise quite okay as far as I'm concerned.
  11. "standard" pyro and deforming mesh

    Ah yes, indeed it works better. It's not entirely flawless, though - there is still that annoying lag behind as if the flames were pursuing the model limbs rather than being attached to it. Fun fact, I did try to crank up the Burn Rate a lot higher but I never tried settng the maximum, and the result is faaar different between 0.99 and 1.0 ! Anyway, in the end, after letting it rest for the night and trying to make it work for a few days, I'm quite dissatisfied with the provided pyro workflow. I'm quite sure I'm not entirely wrong about how I'm doing things but it requires so many patches and fixes to work 'well' that it ends up taking too much time simulating only to get a clunky result. I guess I'm better off with the 'fake' fire methods, temperature field manipulation and all that jazz. I mean, it's like building a house from scratch rather than trying to plug the leak in an old manor. Or something like that. I may be wrong though, and I'd be curious to hear about people successfully getting nice and realistic fires using the pyrosolver model...
  12. "standard" pyro and deforming mesh

    Hey there, I have some panicked people to set on fire. Most of the methods I've seen so far ( and used myself ) were 'hacks', meaning direct temperature field manipulation and/or advection of a custom field. HOWEVER I decided to give the standard combustion model AKA Pyrosolver a try in the hopes I would get more natural and physically correct burning. And well I'm running into quite a lot of issues, one of the most annoying being that the fuel field doesn't 'stick' to the animated / deforming mesh, resulting in the fuel staying up in the air like a trail until it's all burned out. Likewise, temperature and burn do not seem to follow, resulting in flames not sticking to the deforming mesh either, lagging behind since the leftover fuel ignites with a delay. In short, it's a mess, and it's also super slow. So basically I guess my question would be : is the Houdini Pyro combustion model a good fit for burning the hell out of screaming, kicking, little CG people, or is it just too complicated and slow and "locked" ? I've been getting correct results on props and set elements but it looks like a struggle for animated meshes. That's maybe why so many people would rather manipulate temperature ? And if pyro is actually very capable in this situation, how can I make sure the fire correctly sticks to the mesh ? Add a few advection nodes ? Summon an old god ? Summon an old goat ?
  13. Hi there good folks, So I've been asked to make that famous effect of various colored paints layered upon each other, dripping to the ground. The dripping? No biggie. Getting the colors to NOT mix together? Urgh. Or rather, as the flip sim goes, particles spread under / over the other layers, resulting at the end of ends in a spotted mesh with no real foreseable tricks to get all those to look like sharp separations. Here is a good reference : https://www.youtube.com/watch?v=P6TnO_Rr3G4 And another one would be : https://vimeo.com/225438054 How my work looks so far, you can really notice the spots : Aaaand joining a scene. So how could I proceed to prevent the colours from mixing together too much? I've thought of getting a particle force to repel/attract based on color, but it will just make weird things happen. I've thought of getting a texture in there, but I do'nt see how I could make it look right or apply it correctly to the mesh. I've thought of manipulating various fields, adding some kind of divergence, etc, but really I'm not sure what to do. Maybe it's just a post sim trick, too... Paint_drips.hip