Jump to content

Search the Community

Showing results for tags 'expression'.



More search options

  • Search By Tags

    Type tags separated by commas.
  • Search By Author

Content Type


Forums

  • General
    • Lounge/General chat
    • Education
    • Jobs
    • Marketplace
  • Houdini
    • General Houdini Questions
    • Effects
    • Modeling
    • Animation & Rigging
    • Lighting & Rendering
    • Compositing
    • Games
    • Tools (HDA's etc.)
  • Coders Corner
    • HDK : Houdini Development Kit
    • Scripting
    • Shaders
  • Art and Challenges
    • Finished Work
    • Work in Progress
    • VFX Challenge
    • Effects Challenge Archive
  • Systems and Other Applications
    • Other 3d Packages
    • Operating Systems
    • Hardware
    • Pipeline
  • od|force
    • Feedback, Suggestions, Bugs

Found 44 results

  1. Emit Time Range till End Point

    Hey Guys, i got a question. I got a vellum sim and i am emitting every 8th Frame one sphere into my sim. I did it with -> $FF % 8 == 1 but now i want that emission just between Frame 1 - Frame 48. So between F1 and F48 i want every 8th Frame an emission. How can i get this with an expression? Cheers and Thanks!
  2. Hey all, I've been trying to learn more about how loops work, right now I've got a faerie, its wings are expression driven (Sin function tied to a controller) and I have the main build in one shelf with a point cloud that it's instanced to in another. I needed to figure out how to randomly reverse the sin function for points/particles so that they aren't all flapping in unison. Right now I'm close to starting over because I learned maybe a for-each point loop with a timeshift could help, but I feel as though there's a simpler way. Granted this is my third project total in houdini so I'm VERY inexperienced with this. I have the Tokeru site up to help kinda learn how loops work but I'd love some guidance on how to get this to work. Also, what am i screwing up? I tried to export the animation so I could just re-import the baked animation to a particle source so as they spawn in they're offset from each other just based on life, but it doesn't save the animation. Do expression driven animations get baked to disk? To clarify my focuses: I need to completely offset the flapping wings of the instanced copies so they aren't in unison PS: Thank you to anyone who helps, I appreciate it. test_Navi.hip
  3. get orient attribute from point normals
  4. To create a round fencing around house, every cube is aligned in same direction, how can we make to face towards the inner circle like real fence...????
  5. Hi, I am studying python to set a parameter of string (cachePath) by script. After executing the code, ideally it pastes original, "`chs("resouceA")`_`chs("resouceB")`", instead of expanded result "G:/Projects/RnD_000_001/geo_element " So far, I am thinking two methods: A a = r(\"\`chs(\"resouceA\")\`_\`chs(\"resouceB\")\` ") # this way is too many back splash and so confusing B resA = hou.node('.').parm('resourceA').unexpandedString() resA = hou.node('.').parm('resourceB').unexpandedString() a = resA + resB # this way is ok, but when there are 5-10 parmeters, it would be too much work. Do we have a simplest way or special command?? Ideally something like this: a = unexpandedExpression("`chs("resouceA")`_`chs("resouceB")` ") Thanks
  6. Hi everybody, I have one question I'm creating procedural stairs so I have created an attribute name(Steps) and another is (NumPillar), so what I want is, in edit Parameter Interface we can set range but I want the max range should be same as steps value as you can see in image. Blue color indicates steps and red indicates pillar in image file Pillars.jpeg
  7. For loop expression

    Hello, i trying to do something simple but i am knid of new to houdini so i dont know the tricks yet. i have a float number in a for loop that i want to divide by two every iteration. What is the appropriate expression for that?
  8. Hi just wondering if any one could give me any advice on how to write an expression which would set the gravity to 1 for the first 30 frames, back to 0 for until 180 where i would turn back on. At the moment i have if($FF >= 30,0,1) which sets the first 30 frames to active but I'm struggling with re-activating it at frame 180. Any help would be appreciated.
  9. Expression

    Hey, I got a very Basic questin regarding an Expression. So this one: point(stamps("../applyrel1", "SOPPATH", ""), ch("ptgroup"), "P", 1) I´m kinda wondering where "ch("ptgroup") Points to. Ist aiming to a Group Expression Node which contains two Points. But I cant see any actual channel Name called "ptgroup". Is it something inherent or hidden? Ist working but I would like to know why.
  10. Hi, I've tried to cache out .obj files which have the same naming as their import counterparts. I managed to write their original name into a string detail attribute (for example "one200_300-236-58_korpus.obj") - next I thought I could reference those attributes in a filecache node ($HIP/`detail("filecache1",attribute1,0)`) but nothing happens - I just get a file called 0 without any .obj Does someone know whats wrong with my setup? Thank you
  11. I want to get number rounding to the second decimal place. like this -1.2345 -> -1.23 i was do that in Houdini 16.0 : But I cant do that in Houdini 16.5 how can I? sorry, I did not write that I used it Font node. i'd like to use this on Font node. roundDec_example.hipnc
  12. 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
  13. Cant Find "Missing Point"?!

    I've been working on trying to simplify how I can make tear drop shapes (bombs, fuselages, etc). So I got most of it figured, until I stumbled on losing a point during the copy sop. Im always missing the last point from my ramp. Any help would be appreciated. I find myself fighting my brain over "value" and "pos" till the cows come home. HAA. TIA Bill odforceExport.hipnc
  14. Hi guys, As i have pre-roll in my simulation, i am starting my sim from 1000th frame. but this is creating a problem, when i am using the "$F" , because i know it is recognising as frame 1. so that is the help i am looking forward here. how do i fix that ?? i want this $F to be the 1000th frame not the usual first frame. if suppose, there is no solution for that , then all i want is... """i have 100 rigid pieces, and i want each frame to have different pieces staring from 1000.""". i type in piece$F in the blast node, and its starting from frame 1.
  15. I'm trying to drive a BlendShapes' SOP blend parameter using a point attribute, @fade. The @fade is a point attribute and have it's value animated. But the blend parameter doesn't appear to read this animated values and keep showing 0 instead. The question: the blend parameter doesn't work with point attributes? I tried VEX and Hscript forms (@fade and $FADE). The second crashes.
  16. Hey, I got a really stupid question but I can't get it to work ATM. I want to put an expression in e.g. a fluid source node in dops. Something like "if($FF)<225, 1, 0)". So when smaller than frame 225 take 1, else 0 (or another expression like a sin curve). What am I missing here?
  17. I'm using Houdini to render point clouds from depth images, and have everything working for a single frame, but can't get it to evaluate each frame in a sequence. I'm using an expression in the parameter that reads in my image files, so the file path looks like this: D:/UNREAL_WORKING/Brush_VR/Video_Captures/Character_Front/Point_Cloud_Map_01SceneDepthWorldUnits.$F4.exr The $F4 is correctly becoming '0001' on the first frame, but when I slide the timeline around, nothing changes. When I click Expression->Expand String Value, I can see that at each frame it is producing a string that should be reading in the correct file - if I write that same string manually, it pulls in the right file - but it's not actually evaluating the data from the image. What do I need to do to make sure the network is cooked each frame?
  18. expression for cache path

    hi, I have a question about filecache node. Basically I want to construct folders - project folder - HIP folder (save hip file here) - geo folder (cache here) I think 'project set' set $JOBS a file path, then we can use $JOB to make relative path. However, I try to skip that process because I don't like so much, also most productions don't use it. Then I use this expression in file cache node > geometry file `strreplace("$HIP/geo/$OS.bgeo.sc", "HIP/", "")` It seems to be working well, but I wonder if anyone knows a smarter way, let me know.
  19. Currently I wanted to change some rops´s image path parameters with python. I have the problem that python converts my strings with e.g. "$F4" or "$JOB" expressions in it to absolute paths. Can I avoid that? e.g. : c.parm("vm_picture").set("//testDirectory/teststring_$F4.v001.exr") turns to: //testDirectory/teststring_0079.v001.exr How can I set this up with keeping the $JOB or $F expressions in it? is this possible?
  20. Hi there, First time post here. I'm relative new to Houdini and I really love already it but there are some things that (probably) are really simple but I just can't figure out. I must admit that I have very little experience in expressions and python (which I'm already working on) but for something I'm currently working on I'd hope to have some help before I get proficient enough in that. I have a volume source which emits in the Y axis and I wanna use the gas disturb fields but only on the voxels that are being emitted for the first second, after that I want other microsolvers that I have in the scene to take over. What kind of expression should I use for that? Should I first add some kind of life-attribute and then refer to that or is it much simpler? I looked at the local variables in the gas disturb microsolver but as far as I can tell they all refer to the simulation step time which is in the beginning of the whole simulation. Some help ore pointers are really appreciated. Thanks!
  21. Hi, when creating channel defaults inside digital asset I can set it as a value or hscript expression. Is it possible to set it to python expression? A way would be to create OnCreated script which will assign expression to a channel, or use some hscript for executing python command. But I am curious if there is another - better way Juraj
  22. particles path circle

    Hi guys! I've made a sim with particles but I would like to keep them rotate in circle for some seconds and then use their inherit velocity. how i can keep them rotating? i've been trying to add angular velocity with cos ($T * 180) ty = sin ($T * 180) this expression, but doesnt seem to work. any suggestions? thanks!
  23. Hi to all! I'm just starting to study Houdini, and I know I'm only at the beginning, but when I'm following some basic tutorials I see some (weird) expressions that I've never seen before. Ok, thanks to those tutorials I can get that if I need to replicate that exercise I need that expression. But how did they get it? Why that one? Why not another one? Will be I able to do that too one day, without just referencing to another exercise I already did? I'm getting scared that maybe I'm just memorizing random stuff instead of really understanding why of those actions. Was like that for all of you? I will just get use to all the expressions or if it's difficult for me now, so it'll be also in the future? Thanks for sharing Any tips or advise is well accepted
  24. Hello, how can I force a channel in a sop to evaluate my python expression as an expression (not as the final value) ? With hscript it is simple I write : `mycode` But with Python I don't get it, sometimes I write something like : frame() or hou.frame() or hou.pwd() And it is recognized immediately as an expression and is evaluated (blue/cyan background), sometimes the very same text is considered as the final value (background black). I sometimes need to enter the code many times in order to have it recognized as code. I do not understand why ? Any help is very welcome (I am on houdini 15.5.565 on Windows 10) Thanks, Nicolas
  25. So I have a scene that composites a bunch of meshes together. What I want to do is build a descriptive filename based on parameters I have set. For example if the mesh is male or female, what version of pants, or shirt is it using etc. I have a ROP with a two expressions in it. The 2nd expression `chs("switch_LEG_Manual/input")` seems to work fine because it is just concatenating a numeric value (0-5) based on a slider position. However trying to add the string prefix HMM, or HMF I'm not having luck. First I tried to use an IF statement, but could not replace the true, false values of 0 and 1 with strings. So I made some detail - string attributes with the prefixes, and then a switch node to pitch the appropriate prefix, but cannot seem to place that detail string attribute in my filename. Aslo tried a local variable $ATT without success. I have tried, $HIP/Clothes_Fitter_Output/LEG_output/`chs("GENDER/string1")`_LEG_Default.`chs("switch_LEG_Manual/input")`.obj - i get nothing.. _LEG_Default. $HIP/Clothes_Fitter_Output/LEG_output/`chsraw("GENDER/string1")`_LEG_Default.`chs("switch_LEG_Manual/input")`.obj - I get the $ATT local variable but not its actual value of (hmm or hmf) $HIP/Clothes_Fitter_Output/LEG_output/`details("../GENDER","GENDER",0)`_LEG_Default.`chs("switch_LEG_Manual/input")`.obj - Any ideas? or a better approach to making dynamic file names in a rop? Thanks.
×