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Found 58 results

  1. Attached hip file, for a sphere with keyframed animation. In CHOPs, using a channel wrangle, I need to extract the distance travelled , in both cases: (1-green sphere) only tz is keyframed (2-red sphere) all channels are keyframed VEX_extract_distance_travelled.hiplc
  2. Is there a way to blast things across time? Short scenario: I have a set of points, and some of them behave badly some of the time. It's easy to set an attribute on the bad points and kill them, but I don't want the pointcount to vary across time. I have an ID on the points. I would like to be able to check if a point is ever bad, and then kill it at frame 1 - so my output has a constant pointcount with constant IDs of only the points that are never bad. Possible? How? Long story: I'm using a FLIP sim to make points wander nicely across a surface. The bulk motion is great, but the border points behave terribly. I can't delete the border points during the sim, because I lose fluid volume and all my points wander off the edge. Most of the border points stay at the edge of the sim, and it's easy to transfer an attribute to them post-sim and kill them off -- but there are exceptions. Some "good" points wander to the edge and get stuck; some "bad" points work their way off the edge and join the bulk motion. If I'm just blasting the border points as a post process, those few points that escape end up ruining my pointcount. How do I smite them? Thanks in advance!
  3. Confusion about CHOPs

    Alright so I'm just starting to learn about C HOPs and now I understand the basics of it. From what I've learned, all my CHOP networks end with either an export node or a rename node. However, when I right click on parameter > Motion FX... …I get this node tree I have two questions : 1) How does it "export" the data without an export or rename node? I checked the wave node and saw this as the channel name : 'run("chopls ../wave_transform1_clip1")' Not sure what this means or how it works as the export. 2) The math node is set to Combine CHOPs : Add. I know how adding channels are like, but what does it mean to add two CHOPs together?
  4. wave-like information transfer

    I am building a flock using separation, cohesion, and alignment, but I'm modifying the alignment variable. Research showed that you can use a superfluid equation to define the speed of the turn information traveling through the flock, and that helps give the flock that really fluid look. I'm trying to figure out how to control the speed of the information. I need to 1. be able to dynamically change the speed of the information based on the flocks cohesion (when they're more cohesive, the information travels faster) 2. be able to send out "waves" of information every frame, so 24 times a second 3. send out non-disappating waves (I tried the ripple solver, but one of the problems was the dissipation of the magnitude of the wave) I'm thinking CHOPS might be the best bet, but right now I'm just finding a lot of CHOPS information dealing with sound and audio. LMK if anyone knows of a good node that could help me. Right now I'm looking into just hard-coding it in VEX (basically storing the velocity of ALL of the boids at 10 frame intervals), but that will be VERY intensive.
  5. Unreal to Houdini Camera axis Fix

    Hi, I'm trying to export the camera from the Unreal to Houdini, the coordinate system is different in houdini(Y-up) and unreal(Z-up), I tried to get the translations correct which is camera should move towards X in houdini, but local rotation for the camera is still wrong, can we shuffle axis here? Scene file and camera file are attatched below Thank You. camera_import_problem.hip camera_v003.fbx
  6. Hi there! I want to do a procedural animation where I randomly change the transformation every second or so. For example at frame 1 posX is 0, stands still and at frame 50 it moves to a random pos within 10 frames, pauses for 50 frames and moves to next random pos within 10 frames, pauses for 50 frames, moves to next random pos and so on. Unfortunately my knowledge of CHOPs is rather limited and I couldn't figure out how to do it with expressions based on @Time. Any ideas? Cheers, J.
  7. Greetings all! I'm a relative noob to Houdini and trying to replicate a CHOP network that was created a few years ago for a Lynda.com tutorial. I triple-checked and with the exception of frame-ranges, all my nodes and settings are identical to the original, though the one critical difference (presumably) seems to be that in some of the old network's nodes, the Mode is set to "Constant Range" instead of "Range" (node info comparison here). I can't find the place to change this setting - hoping some CHOP ninja can help! Here's ink to a reduced version of the original tutorial file: https://www.dropbox.com/s/zlj9uujmpkap46v/LyndaTutorial_Reduced.zip?dl=0 More importantly, below is a link to a file that contains the original CHOP network (copy/pasted from original file) next to my 'built from scratch' new CHOP network: https://www.dropbox.com/s/4k4rd01j1ja97a8/ForEach_old_vs_new.zip?dl=0 I rebuilt the network because the original was a .hipnc. In above-linked file, I've wired up some side-by-side node networks to show how the CHOP net should be working (works fine with the original) and how it's not working (with my rebuild). Attached is a jpg preview of what the network looks like - I'm ultimately trying to use the CHOP to drive an array of points up a surface. Preemptive thanks to any responders! NpF
  8. Shape Key Question

    Hi there, I’m importing a rigged Character Creator 3 model into Houdini using the fbxcharacterimport node in Kinefx. The model has shape keys used to control facial expressions. In the geometry spreadsheet, these are showing up as primitive attributes. However, when I select the Rig Pose node, these each become detail attributes. My question is, how can I go about accessing these attributes, and using sliders on them to animate them in Kinefx? Or do I need to use chops in some way?
  9. Hello, I have a camera with a lookat constraint targeted at the extracted centroid of my simulation (OUTPUT ANIM LOOKAT) I am trying the play around with some chops nodes to smooth the movement of my camera (the output animation is a bit shaky) but this is doing nothing at all. What am I doing wrong? Thanks a lot
  10. I just want To build Setup for puppet controlled by strings....Maybe we Have already this... Didn't see anywhere I have initial setup/watched some Tutorial ..Just to learn how to control points (Constraints) ..need Some Hand (model I have) ...Hm...Yupiiiii Fun Here some interesting info.. https://voxelpixel.xyz/category/houdini/constraints/ ODPuppet.rar
  11. Hi; Is it possible to deform a line using CHOPs nodes (wave) like the image before? Thanks for helping.
  12. Iso Art

    Just showing some video art I had fun making recently. Pretty simple technically. Low res everything. https://vimeo.com/407189184 https://www.instagram.com/p/B-PX0ryDgB9/?utm_source=ig_web_copy_link
  13. Hi; I would like to control the rotation of one object by another one, using CHOPs. My parent object rotation is on the "Y" axis, but the CHOP node, overrides rotation of the "X" axis..! How can I fit this? Thanks. CHOP.hip
  14. Hi; When we add a MotionFX to a parameter, it adds some scripts in that channel. What kind of scripting language is that? (Please take a look at the image attached). Thanks.
  15. i have a simple audio file that is one note from a bass. using a trigger attribute from SOP piping that into a trigger node in CHOPS i can control where this audio will play. how can i change the pitch of each copy of the audio according to some other value from SOPs?
  16. CHOPS question

    I am working on an audio driven animation using a spectrum and trying to pump up my higher frequency spectrum so it activates as much as the bass lines, but I am struggling with a method. I am currently trying to use a Trim to cut out the lower register, then use a math node to multiply the values, then add them back in. Unfortunately the Trim node is setting the area outside the Trim section to an extension of the minimum and maximum values, but when I try to add the output of my Math node back into the original spectrum it is adding this in too, which is causing a stair step in the channel that I definitely do not want. It works beautifully, except for this one glitch. Help?
  17. My first time messing around with Chops outside of just adding some easy adjusting with motionfx. I'm testing it out just trying to move a sphere with some audio, what am I doing wrong? I appreciate any and all help, thanks. My values aren't super small, I feel that they should be noticeable. Here I'm doing " chop("/obj/chop_music_OUT_music/") " is this not the correct way of referencing the node within chops? / getting the audio data ? I feel like I'm making a dumb mistake somewhere but I've been stuck for a few hours, any help is welcomed. If you guys have any links to more recent tutorials covering that topic that would be helpful as well, thanks so much.
  18. creating sound from animated curves

    Hello, I have an experiment where I want to create sounds from a set of deforming curves, like the strings of an instrument. For that I'm driving the pitch control of an oscillator. It works just fine for one curve, and also with several if I set them up one by one. However, in the end I'd like to have a lot of curves and I wanted to get them all in via one geometry node in my chop network. Using the point name attribute in the geometry node I have all my channels coming in correctly. i.e prim_0_pitch1, prim_0_pitch2, prim_n_pitch1 etc. I couldn't figure out how to make use of the channel groups iteration method of the foreach node and ended up iterating over the whole set "over numbers" and deleting all channels I don't want. Sadly I can't feedback like in a sop foreach to get all the channels back again.. I'm stuck and I'd be glad for some hints, or maybe there is a better approach? Thanks in advance! seb soundstrings_test.hipnc PS: Another strange thing - whenever I connect the foreach loop to the out null, the filesize increases to 30mb (from 400kb) and the only way to fix that is deleting the foreach node - in any case, to hear the sound please connect it after opening!
  19. SideFX Houdini Masterclass - Louis-Philippe Clavet Following the Everything Procedural conference, Breda University of Applied Sciences will host a two-day SideFX Houdini Masterclass by Louis-Philippe Clavet. This is an unique opportunity to learn, experience and get acquainted with one of the most versatile procedural content generation tools. Day 1: SideFX Houdini - Procedural Animation Houdini has long been known for its great ability to reproduce the motion of many natural phenomena through its dynamic operators. Even if they are fantastic tools, some movements are hard to generate with these systems. A procedural animation approach seems to be a great alternative to infuse life into a cg scene when artists need more intuitive ways to bend motion to their will. Through skillful attribute manipulations and a clever use of CHOPs, you will experiment what can be put into motion with a limited use of dynamic simulation and keyframe animation. This masterclass is a collection of test scenes built to showcase the versatility of procedural animations in Houdini. It is intended to Houdini users of all levels, but requires a good knowledge of how to navigate the software and its interface. Day 2: SideFX Houdini - Procedural Dependency Graph (PDG) Discover the new context introduced in the most recently announced version of SideFX Houdini. Houdini now offers us a visual management system that handles all tasks and all dependencies in which TOPs (Task Operators) are the new set of nodes tailored to improve workflows and pipelines. Learn how to deal with the challenges of creating and working with a great amount of data. Experiment how this system can also help artists to automate tasks that they do on a daily basis. This masterclass is an overview of the new technology. It is intended to Houdini users of all levels, but requires a good knowledge of how to navigate the software and its interface. The Masterclass is a two-day event (both 9:00-17:00) and takes place on Thursday April 25th and Friday April 26th. The Masterclass will be hosted in a workshop setting with live presentations, demonstrations, hands-on experimentation and exercises. You need to bring your own hardware (laptop is sufficient) to be able to actively participate. http://everythingprocedural.com/ https://twitter.com/everythingproc https://www.facebook.com/everythingprocedural
  20. Error channel Node Chop Network

    Does anyone know why i get this error in mu Channel node i created and attribute , for my chop network? Thx in regards
  21. Hi, I constraint two objects together with chops. Everything works until I use expressions in my parent object. What do I have to do to fetch expression values into chops? kind regards Jon express_chop.hip
  22. Hello peeps, I'm trying to figure out something similar to some sort of ribbon setup in Houdini. Still, lots to do but right now I'm trying to work out rotations, I have twist working by itself such that if I twist the ribbon the bone rotates accordingly and bend working by itself as well, however, if I twist and bend the ribbon at the same time, the rotations become unstable. How can I fix this? Any help is much appreciated!!! Thanks. ribbon_setup_test_01.hip
  23. Hi guys, I'm having some trouble using bone length for squash and stretch as its giving me crazy deformations that I cant fix. (see attached file) if anyone knows how I can solve this, it would be much appreciated. Also, the other problem is, how would I implement volume preservation with the squashing and stretching? In maya, we would use the joint scale but Houdini seems to give weird results if I scale bones. Any help is much appreciated. Thanks. rigging_bone_stretchy_problem_01.hip
  24. My Original Question is still posted bellow, but i have since figured out a solution to get what I want. Basically in CHOPs I have a null with a string parameter with a multi line python expression on it. This expression produces a string with all the channel names in it. refNode = hou.node('/ch/ch1/noise1') tracks = "__TEMPSTRING__" iteration = 0 trackTuple = refNode.tracks() for track in trackTuple: curTrackString = str(track).split(" in ")[0] curTrackString = curTrackString.split("<hou.Track ")[1] if iteration == 0: tracks = curTrackString else: tracks = "{0} {1}".format(tracks, curTrackString) iteration += 1 return(tracks) Just make sure that "refNode" is referencing the node you want to get the channels from and this should work for you as well -- ORIGINAL QUESTION -- Hey guys. I need to be able to the names of all the channels that exist on a particular CHOP into a string parameter field (as shown below). There is a VEX Function called "chnames" which gets me the names but then I don't know what to do with it. I've promoted the names to a clip attribute but I have absolutely no idea how to access said attribute in an expression. So my two ideas are either to... 1) Stick with the Clip Attribute and somehow reference that in an expression OR 2) Somehow execute the "chnames" VEX function in an expression/parameter field (which I don't even think is possible but putting it out there just in case) If anyone knows how to do either of these things or has another method that'd work please let me know. I'm about to explode from the frustration of trying to figure this out!
  25. Hey Guys. I've import some midi files into chops. Each time a key is pressed, it creates a flat peak, and then goes down to zero. So basically I've got a bunch of channels with localised plateau peaks. What I want to do is essentially extend the tops of these peaks until a new plateau is reached, at which point I will extend that plateau out the the next one, and so on. I've gone ahead and done this in SOPs to illustrate what I'm trying to do (cause that explanation above likely made no sense). The pseudo code for what I want to do is: maxVal = value of sample0; foreach sample (excluding 0){ curVal = the value of the current sample; if curVal is equal to 0{ Current Sample Value is set to the maxVal; } else { maxVal is set to the curVal; } } This is the logic I followed in SOPs and it worked perfectly. However I cannot figure out how to do the same thing in CHOPs. My problems are two fold. 1) I can't figure out how to set the value of samples that are NOT the current one being iterated on. The way I've found so far to set sample values is using the global variable V. I tried to do it using the 'chsetattr' function, but either it doesn't set sample values or "V" is not the right attribute to use (and I can't find the correct one). Also tried setting a sample attribute on one wrangle, then on another (with iterate set to channels and samples) set "V" to the value of the attribute. Also didn't work. 2) So far I have found no way of only executing the code once (such as in a detail wrangle, which is what I used for the SOPs example). I thought setting the wrangle to iterate by "Over Channels" would do the trick, as the documentation says, "Runs the snippet one time per channel with the I variable set to zero." but in this this post Guillaume points out that this isn't the case. And even if it was I still would be in trouble because that mode does allow setting "V" or channel data. 2.5) On that note, whats the difference between channel data and attributes? One can be written the other can't. I thought attributes were just data stored on the geo (or in this case channel). Not sure why CHOPs is suddenly making a distinction. So to summarise, I need to find a way to set the values of individual samples and I need a way of executing a CHOP wrangle once per channel (like a detail wrangle in SOPs).