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About freejonah

  • Birthday 07/14/1971

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    venice, ca
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    keeping it together

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  1. Hey this is really helpful. I loaded your file and rendered it and it looks correct, so that's great. I have a couple of questions. I don't see "Create Cryptomatte Material IDs From Not Available Materials" anywhere on the .obj properties area. I assume that's because I'm using Houdini 18.5.633 ? Anyway it seems to work so the default must be fine. But this is a really interesting methodology. I am not actually doing any instancing, but the methodology works fine when you just add a random "shop_materialpath" primitive attribute to the primitives themselves. Here is the pig head copied without any instancing at all. Just 88,000 polygons copied on points. Works like a charm. Obviously it screws with your actual rgb pass but as you said you can run out separate passes.
  2. When rendering in Redshift, in the rop under the AOV section you can select cryptomatte as a custom output. There are four ID Type options you can choose from: Node Name Material Name Object ID Custom Name ID Does anybody know how to make option #4 work? It seems like there's a very powerful component to the cryptomatte functionality that nobody is using, unless i'm mistaken. There's no better program than Houdini at making carefully placed and named attributes, but what do you do? I tried making a primitive attribute called "Name" but that did nothing. Is this even implemented in Houdini?
  3. Hi folks. I have a pretty rudimentary question about rendering Redshift with cryptomattes out of Houdini. When you choose cryptomattes as part of your AOVs, it creates a separate file like this: element_v01.$F4.exr element_v01.$F4.cryptomatte.exr I would prefer to have all the channels in the primary image, but if it has to be a separate file my issue is that the Flame can't read that cryptomatte as a sequence because the ".cryptomatte" is between the framenumber and the extension.
  4. Thanks Pirminus. I do actually want the fragments to fall. I just want them to stick together a bit before doing so. Kind of like crash glass for a windshield. I tinkered with it a bit with some guidance from you and some others. I have the constraints wired properly I think and also I realized my name attribute needed to be promoted. The problem is still that I can't get the behavior I want. The constraints either connect everything together into a big garlic knot or they do nothing. Attached is a new hip file with some adjustments. Still not great but better. Any advice on settings and tricks would be appreciated. moving_constraints2.hip
  5. Houdini community, Hoping to get some advice with something that has me stumped. I've attached a hip file to demonstrate the situation. I'm attempting to create a controlled shatter on a moving object using the Bullet_Solver sop. I've gotten as far as animating my pieces to be active or inactive so they release from the animated object as required, collide, etc. My big issue is how to make use of constraints here. I want to have glue constraints keeping things sticking together in a more interesting way but I can't seem to get them to do anything. Should the constraints themselves be moving or static? Does that matter? Should I create them a different way? Any help would be appreciated. Thank you. moving_constraints.hip
  6. Gentlemen, just wanted to mention that this saved my ass. Ectomaniac, you are correct that there is very very little documentation about this very problem. I struggle with the whole "animated to sim" jump. Drives me crazy how many attributes and influences cannot be changed per frame to build a simulation.
  7. Thanks Atom. No my refraction and reflection limits are quite high. It's just refracting darkness around it
  8. I was hoping somebody could help me with a render of a glass bottle filled with fluid. I am using the RS_Material node with the stock glass preset. I'm attempting to get the refraction of the fluid to function as it would in real life where the liquid appears to go right to the edge of the glass. None of the IOR settings get me there, unfortunately. My model is double sided and the normals are correctly pointing outward on the outside and inward on the inside. The fluid is slightly backed off of the interior surface so we're not penetrating. No matter what I do I can't get the refraction to bend "out", but it will bend "in" no problem. I have a few images attached that show what the different settings are. As you can see, an IOR below 1 ( IOR_0.85.jpg ) correctly pulls the liquid inward as you would expect. An IOR of 1.0 causes the glass to disappear altogether. Nothing I do above 1.51 gets the opposite effect, so you're always seeing the glass thickness represented as a big transparent border. Any advice would be appreciated. Thank you.
  9. I get it. You're saying that I should generate a bunch of my own attributes that won't be modified during the sim as persistent containers. Name them whatever I like so I have access to them in the Vex expression area. That makes great sense. I get it's time to put my wet suit on and dive into that HDA and see what's going on in there Thanks for taking the time to help me out. I appreciate it.
  10. Thanks Tomas. This is great information. I kind of feel like an example file in the Vellum Constrain Property section of the Houdini help would be really helpful. I have been digging for a while and I've never found anything in the documentation about using "orig" suffix on standard constraint attributes. Also this separate base and exponent component phenom is a bit of a black box as well. Would you happen to have a lead on documentation about this sort of thing?
  11. I'm building a relatively complex Vellum DOP setup using multiple objects with different constraint arrangements. The issue I'm having is my usual Achilles heel with this sort of thing: modifying attributes and values mid-sim. My specific issue is that I have a Vellum cloth object that is using the Pin to Target constraint option to follow some geometry I'm animating in SOPs. I created a point attribute for the target weights and that's working fine. My problem is that around halfway through the sim I want to animate down the target influence for this specific pin constraint. I have partially solved the problem using the Vellum Constraint Property DOP and animating the "Remove" value from 0 to 1 at the frame I want the pins to disengage. This works nicely as long as you're careful to select the specific constraint geo in the Group field of that DOP it will work. It's working so I'm going to get through this project using this method, but I'm having a really hard time figuring out how to modify my existing per-point constraint values using these fields. My questions: There are a bunch of specific vellum constraint attributes represented like Stiffness, Damping Ratio, etc. in the Vellum Constraint Property DOP that I can play with over time. Are these scalars that multiply by the point attributes I already have? Or are they values that will override the ones I've already set? Assuming they are overrides, is this why the VEXpression toggle and field is there? If I do something like "stiffness=stiffness*(fit($FF,50,100,0,1)" will this remember the original value of stiffness or is that being reset each frame? There is also the SOP solver methodology where I can modify the definition of the Constraint Geo over time. I can always fall back on that but it's also kind of tricky to setup. Hoping for something simple and effective that can just be wired into my DOP network. I really rely on the Sidefx example files to guide me through a lot of these setups, but I find that these kinds of constraint modification setups are in short supply. Would love to know how everyone handles this sort of thing. If anyone has guidance on this sort of thing, let's discuss. Thanks community.
  12. Hi guys. Thanks for the sidebar help and private messages. I realize now that it was a lot simpler than I was making it as usual. I found that using more than 4 constraints on a piece of furniture was overkill so I created a string that allows you to easily pick which ones you want to engage the sim while bypassing the ones you don't. Attached is the demo file we discussed. It's simple but I'm pretty sure some of you guys will know of a cleaner way to do it. If you have something to share that would make this work better I'd be happy to take a look. Hip file here bumping.18.hip
  13. Sorry I guess I wasn't clear what I'm talking about. I wanted to just have 3 rbd objects bumping into one another. My thinking was that I could animate the objects and then have pin constraints created based on that animation. Each of the 3 objects would then be attached to their relative constraints. The DOP network would have an RBD object for each piece of furniture that is doing it's best to follow the motion. does that make sense?
  14. I have a project coming up that will require me to hand animate objects but get them to collide with one another. I'm an experienced Houdini user but setting up DOP simulations has never been my strength. I've attached a hip file with the basic situation here: moving_furniture.hip Furniture will be sliding around, probably animated by hand. The objects need to bump into one another and react naturally while doing their best to follow the target animation. I had assumed that this would be some sort of combination of RBD objects, proxy Geo & pin constraints, but I've been unable to understand how to wire it up. There are so many great examples using this sort of thing but nothing that really explains how to combine following constraints that are animated in world space. Thanks so much
  15. Hi everyone. I'm looking down the barrel at a very cool project that involves creating a CG wind sock and blowing it around in the air. After poking around in Dops for a while I decided it would be a good idea to involve the expert Houdini community. Essentially I need to create a wind sock that has air flowing through it, bending it, flapping it, etc. I also have to animate it like a character. My idea was to create a soft body simulation of some sort that uses a sop animated cage as a target. If anyone would like to prototype it I am attaching a hip file that sets an example scene up. My intention was to post an example of where I was at but my attempts have been so unsuccessful I didn't want to contaminate everyone's thinking. The sop "TARGET_FOR_DOPS" is just a stand in for the keyframed animation I will need to follow. Thanks in advance to anyone with any ideas they can share. I'm very grateful as we are a bit of a pickle here. wind_sock.hip
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