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Everything posted by Kaprolactam

  1. Hey everyone, so I've set up a scene with a principled shader and it rendered fine when I exported it to ifds and rendered it on our farm. But then I needed an extra AoV for an attribute to mask out parts of the object that has the shader assigned. In order to get that to render, I opened the principled shader and did a simple bind->bind export setup for that variable which then rendered fine locally. But from then on, no matter what I tried when exporting the scene to ifds, the object with the open principled shader would always render as if it has no material assigned. I tried forcing VEX shader embedding, which made the ifds quite a bit bigger and made me hopeful, but to no avail, all I get is grey shading. For now, I render the mask as a constant material in a separate mantra node but there has to be a way to output an attribute in an AoV when using the premade shaders. Any help is very welcome!. Thanks in advance, Paul
  2. Rhythmic particle emission

    So it happens like it usually does, right after posting my cry for help, I discover the checkbox for probabilistic emission, unchecking which is exactly the solution I was looking for. So in case, anybody else looks for it, the pop source node has the option in question.
  3. Rhythmic particle emission

    Hey everyone, this seems like a rather trivial thing, however, I'm a bit stuck. I'm currently working on an AA gun-asset to create tracer fire for a couple of night shots, but I'm having trouble getting the pop source to emit a constant stream of particles. It works if I set the emission to once every frame or once per substep, but for all other combinations of timings I tried, I get a stuttered particle stream with lumps and gaps. I must be missing something here. Surely there is a way to quantize the particle emission to be more regular? Thanks in advance! aa_asset_dev_v001.hip
  4. Reflection with alpha

    Hey everyone, I've got a question that, even after lengthy research still has me stumped. I've got a pyro fireball and a ground geometry that reflects the fireball. The simple question is: How do I set up the ground plane and its material so it reflects the fireball, including alpha, and just gives me a black alpha where there is nothing to reflect? I've tried to force it to phantom, that just makes it invisible, other, somewhat hacky workarounds like this one are rather old and in the SHOP context. Nothing I tried seems to work. When I'm working in 3ds max and Vray, I use this technique all the time (vray object properties -> reflection/refraction matte), I just don't get how this can be this much of a faff in Houdini, so I'm probably missing something pretty obvious. I'm grateful for any and all help, thanks in advance!
  5. How to cache a really heavy flip sim ?

    You're correct. The sim files go in the initial state of your dop network. Also, be wary of the amount of sim files you dump, since they contain all the simulation data, they tend to be on the very large side. "Checkpoint trail length" (the number of checkpoint files to be kept simultaneously) and "checkpoint interval" are your friends here.
  6. How to cache a really heavy flip sim ?

    There are two options: One is doing a distributed fluid sim, which enables you to slice your sim into chunks that you can simulate on different computers at the same time. This should get you up to speed: https://www.sidefx.com/docs/houdini/dyno/distribute.html If you just want to be able to continue simulations, have a look at checkpoints that you can set in the properties of your Dop network: https://www.sidefx.com/docs/houdini/nodes/obj/dopnet.html These will enable you to continue your sim from the last checkpoint, as opposed to having to redo the sim from the start. Both techniques have their advantages and disadvantages, you'll have to see what works for you.
  7. Fire on the ceiling

    Hi everyone, I'm currently trying to create an effect of fire burning under a ceiling, looking something like this: http://footage.framepool.com/en/shot/774901137-explosive-flame-fire-disaster-ceiling-fire-blaze As far as I understand the phenomenon there is a layer of gas floating between the air below and the ceiling above. It gets ignited and starts burning at the interface between air and gas. The flames rising up create this kind of nodule structure by constricting the gas into little pockets. This is the theory but I'm completely stumped on how to create the actual effect. I've tried creating little pockets of fuel but the pyro sim simply burns into them, disregarding the fact that there should be no air that makes combustion possible. Does anyone have some experience with this kind of simulation or at least an idea how to tackle it? Any help is appreciated. Thanks in advance Paul
  8. World Space Position?

    Oh joy of joys, I found the solution, as usual, right after posting the question, and it is indeed rather obvious. A Transform (matrix) node (the one with the red icon) with its default settings does exactly what I need, i.e transforming the current space to object or world space and the noise stays in place.
  9. World Space Position?

    Hi everyone, I've got a problem that has me stumped. In my setup, I'm flying with a camera through a volume that has its density modulated via a couple of noises in the mat context. But whatever I do, I'm unable to make the noises stick to their position, it seems like the P attribute from the globals node is always in camera space. I must be missing something obvious since a lengthy internet search didn't give me any meaningful results. I've attached my file, to observe the problem just render a frame and then jump to another frame, the camera will have moved but the noise pattern is in exactly the same place. Thanks in advance Paul world_space_noise.hip
  10. Modulating Motion Blur

    That's exactly what I was looking for! I didn't know, that there actually are render settings hidden in the parameter interface that don't show up by default. Thanks a lot!
  11. Modulating Motion Blur

    Hello, you helpful people, I'm currently doing snow VFX and I'm a bit bothered by the tube-like look of the mantra motion blur. I'm also using VRay quite a bit which has some helpful features to make the motion blur look less sterile, especially two settings, as shown below. The first setting allows me to move more samples towards the centre of the time interval, simulating a shutter that's not instantly opening and closing. The second setting allows me to move more samples towards the front or the back of the interval. Using the two settings combined, I've quite a lot of control over the look of the motion blur. Is there anything comparable in Houdini or are there some tricks to emulate that look? I think I've diligently read what I could find about motion blur and mantra but I couldn't find anything comparable. Thanks in advance! Paul
  12. Granular Sheet - Moving Pin Constraints

    Hey everyone, after unsuccessfully scouring the web and the two big Houdini forums I finally brought myself to asking directly. I'm currently trying to animate a sheet of cloth using a granular sheet since the FEM approach is just excruciatingly slow. I've found three methods for pinning parts of the granular sheet in position (@stuck, @mass = 0, @targetP) but I wasn't able to find a use either of these methods for an animated pin constraint. I'm obviously still not really proficient in Houdini since this problem has me completely stumped. So if any of you lovely people would point me in the right direction, I'd be immensely grateful. Thanks in advance! *edit: After searching some more, I came across this thread: While the file attached to the thread works when I play it, when I try to copy that setup into my scene, it just refuses to work, even though the @targetP gets updated. Obviously, I'm doing something wrong but even comparing the node settings side by side I can't for the life of me figure out what that something is. *edit #2: Okay, I finally figured it out. I didn't realize that the sop solver node is empty by default and you have to create the sop structure to update every frame by yourself. Now that I've figured that out it is perfectly reasonable, I just didn't think of that for quite some time. dia3_dmo_001_010_cgfx_setup_v003_pj_stripped.hip
  13. Granular Sheet - Moving Pin Constraints

    Yes, it works. I've got several other things to figure out but this, fortunately, isn't one of them anymore. And yes, I knew that the sop solver would have to update the targetP every frame, it just didn't dawn on me that I have to dive inside the solver until I noticed that it doesn't have that little icon of a closed padlock next to it. After that, it was blindingly obvious. Oh well, you live and learn.
  14. DOP Checkpoints disable simulation

    Hello everyone, so we finally got the full FX license for Houdini and I merrily went about rebuilding a setup that I built in the apprentice version, some FLIP shenanigans. The apprentice version wouldn't simulate when I enabled checkpoints, I thought that was so you can't simulate in apprentice and use the cache in the full version. But now I've got the paid license and the problem persists. I set up the checkpoint file name but no matter what interval or trail length I set, all it ever does is simulate frame 1 and write it to disk, then stop simulating the DOP network, showing me memory cache blue in the playbar and just playing the animation. I'm stumped. Is there anything I'm missing or is it a bug in H16? Any help is appreciated. Thanks in advance Paul
  15. DOP Checkpoints disable simulation

    Okay, I'm a complete and utter moron. After much fiddling without any results, I resorted to reading the manual on the DOP node again. Carefully. And I found what I was doing wrong, namely using $F4 as numbering variable, not $SF as stated in the manual. I guess that could have been made more clear in the interface, maybe with a warning or something but you live and learn. Won't make that mistake again, that's for sure.
  16. Trouble with POP Proximity

    Hi all, I'm currently trying to simulate droplets running down a box that suck up (kill) droplets in their path. So I thought that the proximity node should be perfect for this, only to realize that it's giving me a lot of trouble. If you kindly have a look at the attached file, there are plenty of particles around so that all particles should be triggered by the POP proximity and thus added to the group that in turn colors them red. But it just doesn't happen! What I see here is that over a couple of frames the proximity is triggered for more and more particles but not for all of them and they should be plenty close enough to each other. I'm completely at loss as to why that is the case. Maybe someone of you would be so nice and enlighten me what I'm doing wrong. Thanks in advance!
  17. Trouble with POP Proximity

    So, after much faffing about I found the solution, albeit I can't say I understand why it works. Apparently there is a difference between plugging scattered points into the popnet and then emitting by points and plugging the geometry straight into the popnet and then using the source node to scatter particles onto the surface. The latter works with the POP proximity, the former doesn't. Pretty weird.
  18. Unrolling road

    Hello gang, I've been lurking for a while and learning a lot from you, but now the time has come for me to ask for your help. I'm currently trying to animate an unrolling road that is swerving through the landscape. I've already got a setup that somewhat works, although it's probably pretty convoluted and unnecessarily complicated. This is what I did: - Create a spiral curve - Animate a carve-SOP to cut it down from edge to center - Position the carved spiral at the end of my path curve that's also animated with a carve. - Fuse the two and create a sweep. My problem is, however, that I get lots of issues with the UVs and the fusing at the transition between the two. Maybe one of you experts can have a look at my scene and give me some suggestions as to how to improve my setup? Thanks a lot in advance Paul rolling_road_v004.hip
  19. Unrolling road

    Thank you for the explanation. Most of it I understood just by looking at your setup, but every bit of information helps. I noticed that I tend to use too many VOP SOPs even though there is a node that does just what I need, for example the PolyFrame that I never used before. Cool stuff. Cheers and thanks again!
  20. Unrolling road

    Thank you so much, yongbin, this is perfect. Now I'll just have to figure out what you are doing in there... :-)