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About freejonah

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  • Birthday 07/14/1971

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    venice, ca
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    keeping it together

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  1. Redshift IOR Glass issue

    Thanks Atom. No my refraction and reflection limits are quite high. It's just refracting darkness around it
  2. Redshift IOR Glass issue

    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.
  3. modifying vellum constraints over time

    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.
  4. modifying vellum constraints over time

    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?
  5. 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.
  6. Animated colliding objects

    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
  7. Animated colliding objects

    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?
  8. Animated colliding objects

    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
  9. inflatable wind sock

    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
  10. 6 axis robot arm rig

    I'm looking for a good solution for creating an IK rig that behaves like a 6 axis robot arm like one would see in a modern car factory. This means each rotation axis would be heavily constrained to it's own rotation axis. My target that the rig will follow is a matchmove so it needs to follow it exactly. In theory a six degree robot should be able to follow any point in space, but the math escapes me right now. Have any of you done something like this? Curious to see what's been done in the community. Thanks in advance, Jonah
  11. Looking for floating object ideas

    Genius Houdini Community! I'm having a hard time wrapping my head around something so I thought it best to ask the experts out there. We're about to do a project where a rigid object ( like a box or a tea kettle ) is floating weightlessly in a room. It is being blown around by wind and bumping into objects as it goes. What we would like to do is loosely keyframe the object for basic choreography and timing but have the dynamic object "follow" it, like a target. This way you get the benefit of having keyframed motion influencing the dynamics. Would a sop solver be the right way to go here? Field force? It's been a while since I used dops so any advice or examples would be appreciated. I'm sure there's an elegant solution out there but I'm just not able to think of it. Thanks very much!
  12. altering scale with ODE objects

    In an attempt to simulate the way bubbles in a head of foam grow and push each other around, I'm trying to use the ODE solver. The problem is a lack of any kind of scale control on each individual sphere primitive. Toggling on "Use Deforming Geometry" seems to do nothing to the influencing radius as the simulation runs. The goal is to have lots of little spheres pushing against one another, but with some of them getting bigger and pushing the others out of the way as the simulation grows. I can't figure out how to do this, unfortunately. Advice, or better yet, example hip files are welcome! Thanks in advance Odforce community.
  13. Camera UV coordinates in a Shader

    HI there, Sometimes I find myself doing projects with lots and lots of prebaked geometry data that is a hassle to go back and recook. In these cases I really wish I could tell my surface shader to look up some coordinates from a projection camera ( OTHER than my rendering camera ) that I've set up without having to go back and bake in UV coordinates on the points or vertices. I see that you can do something in Light_NDC space, which is cool. I would like to do the same transform in a camera_NDC space.
  14. sculpting volumes

    Here is a quick demonstration of what sort of thing I'm building. In the hip file note that I've made a slightly modified version of "billowy_smoke" to properly utilize the uvw volume, plus it treats the noise a bit differently. If anyone has a better way of doing this uvw buffer stuffing thing I've doing, like in the volume vop, please share. Thanks! post.hip volume_test.mov
  15. sculpting volumes

    not sure. what am I looking at?