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Found 83 results

  1. Hi all, I've been practicing and experimenting with VEX in Houdini and I challenged myself to see how far I can go with only VEX and VOP. I did successfully manage to create this simple effect without any use of dynamic simulation (DOP). https://vimeo.com/375250070 Basic Summary: A particle system that computes at frame-basis. I can jump from frame 1 to 700 without waiting for simulation. Instead of the traditional age/life computation, this system uses travel speed to compute. Trajectory generated with polar coordinate + Flow Noise on sphere section. The graph mainly consist of VEXs. There's still room to be improved definitely, if anyone is building more upon this, please share it, would love to see it. I think at the end of the day, this kind of system is probably not entirely practical tbh, but it's a great practice and study on coding with VEX. (SHOUTOUT to a best friend of mine who's studying mechanical engineering, helped me to find a way to calculate the spiral length.) HIP file here: FX_Rasengan_v01.hipnc Happy Coding!
  2. Hello, Can you please help me a little bit? I would like to animate the direction of my normals based on the anti aliased flow noise in point vop. Can you tell me which nodes should I use to get this result? Thank you
  3. Custom Velocity with Volume VOP

    Hello there, I'm making a classic Ship Sailing Effects (ocean guided). I'd like to add a custom velocity to the bow of the ship in order for me to have a good turbolence like this: Through a Volume VOP (please see the hip attached) I created the following velocity: The shape I had it's what I want (straight velocity to the front and curved ones along the sides of the ship, so they can push the water for having a classic V shape). However, I'd like to invert the value of it: having higher velocity in the center e gradually less on the side. With my solution I have to much velocity on the side and less on the center of the bow. Basically I need the trails to be red (high) at Z=0 and blue (low) at the Max Z bbox. Furthermore, is my solution right? I blast a part of the bow, scattered it and then use a Volume Rasterize Attributes for creating the velocity. And, lastly, what kind of operation do I need to use in DOP in Volume Source? Somebody says "Add", somebody "Pull". What is the correct way? I hope you can help me. Any suggestion will be really appreciated. Ship_Body.obj Ship_Custom_Velocity.hipnc
  4. Curl Noise functions in voplib.h

    Ahoy there!!! A quick question... I'm writing VEX noise functions but is a bit confused with Curl Noise functions. It's not like that I didnt get it. Of course I get it but is stuck in this weird functions in voplib.h. Here's what I'm stuck with.... Down below is the Code. why is xDiffNoise yDiffNoise and zDiffNoise there anyways. I couldnt find a function that's making use of it. Maybe I'm missing some. But please somebody explain it to me. Just to say... I'm writing a Curl Vex Function with all the Noise options. Thanks. noisevec = onoise(pos*freq - offset, turb, rough, atten) * amp; xDiffNoise = onoise(xDiff*freq - offset, turb, rough, atten) * amp; yDiffNoise = onoise(yDiff*freq - offset, turb, rough, atten) * amp; zDiffNoise = onoise(zDiff*freq - offset, turb, rough, atten) * amp;
  5. Hi All, I'm looking for some help. I'm digging into shading VOPs and want to set some conditional switches. Unfortunately, I could not find relevant references for this particular case. I want to check if the Texture node (Opacity) has a valid link and switch to a constraint if not. Two-way switch is set to RGB color. It does not work the way I thought it should. What do I miss here? Maybe is there another, more obvious way to achieve it? Thanks a lot!
  6. OceanVortex question

    I'm trying to simulate WaterVoltex with Houdini. This is a tutorial on sidefx that is not ours but a credible site. I do not understand, so I ask here. I have set up like a video but the results are not the same. Heap files and video links, I'll leave time Thank you for your help. The reason for this simulation is to create a water simulation using the ship. I will attach a reference video on this If you have any other approach, welcome any way. I will show my enthusiasm to learn Houdini. Thank you for your interest. Plz.. Related Videos Link (19:21 ~ 25:49) Reference Video (4:21 ~ end) voltextest.zip
  7. Hello I am trying to mix/combine the density and colour of two different VDBs into one VDB in Houdini (image 1, file attached). For the most part, this is working as desired but there are two main issues: 1. Pink fuzzy edges around the blue VDB - How do I get nice clean edges where the blue VDB smoothly fades out to transparent? (image 2) 2. Blue VDB does not go all the way to the border of the pink VDB - How do I make sure both VDBs finish on the same outside border? (image 3) I have tried adjusting the voxel size, changing the set up of the VDBs (ie. the exterior/interior band voxels, fill interior) but I can't seem to get it working the way I want. Can anyone please help me? I have only been learning Houdini for just over a month so example files would be helpful. Thank you! Mix VDBs.hip
  8. Non-Simulated Flame (+hipfile & notes)

    Thought it would be cool to share some R&D i worked on for creating a flame FX without doing any simulation purely through deforming geo. A pretty simple FX nothing too crazy but i though i should share it as some people might be trying to do similar things. I've included the Hip file as well as notes explaining the vop workflows. I'm very much a novice to Houdini's more technical side so excuse any rookie mistakes, critique welcome as well if you think i can improve my workflow. Non_Simulated_Flame.hipnc
  9. how to import point (attribute VOP)

    Hello guys! Can U help me with small problem? I dont know how to import all of the points from scatter to attribvop (to get to an same gradient for all of them)?? Can u give me any advices? Thank you so much! hip. hile in attach how_to_import_all_points.hip
  10. Hello guys! Can U help me with small problem? I dont know how to import all of the points from scatter to attribvop (to get to an same gradient for all of them)?? Can u give me any advices? Thank you so much! hip. hile in attach how_to_import_all_points.hip
  11. hello, i have a curve in 3d space with an organic shape and i want to resample it so it becomes jagged but maintaining its features. So i was thinking i should compare the tangent value of each point with its next one and if the difference is big it means the curve is changing direction so i keep that point. If there is no big change in direction i remove points. But i have no idea how to implement this in Vop or Vex, i am new to Houdini. Any ideas?
  12. I'm running a for-each-connected loop, and need to rotate separate shape such that the largest face is down, for example the one marked L is the largest for the shape in the image. I have a theoretical idea, no clue how to implement it, and not sure if there is a faster or simpler way: (1) get the largest face (no idea how) (2) rotate till the normal of the largest face is facing down Again it's too theoretical, but if you have a way that would turn these flat on they largest face I'll be grateful
  13. Hi, I am just a newbie start learning Houdini. I am following Side FX's tutorials from very beginning. I was watching PWQUINT's 'Sop Solver' tutorial and having trouble. Tutorial show me using SOP Solver DOP to control attribute. So, I did create custom point attribute 'heat' and using for loop and if loop to increase 'heat' value frame by frame, also increase neighbor points' too. There is example file by PWQUIT but For Loop and If Loop vop was different and I tried to follow it with H17 but not working. I cannot find which part I missed. Thank you for reading my question. sopsolver_v001.hipnc
  14. Hi Guys I have a question for chramp function I moved RampValue using Addvop or Add function wrangle worked Look like repeat and vop worked clamp I don't know why two output is different (Left image uses Wrangle Node and the right image uses Vop Node) I think Solution is same , but result is different I wonder why this results chramp.hipnc
  15. Hey! Could someone help me understand this? I have noise going into the vector displacement of a principled shader. Why do I have change the amplitude of the noise in z-axis to affect the y (up/down) position? If I do the same at sop level I can just adjust the amplitude in the y value. I tried messing around with the transform vop, but I didn't get anything working. Thanks displace.hiplc
  16. Hi everyone! I need to do a local rotation using an Attribute VOP for individual points of a grid and just can't get my head around this... If I e.g. rotate along the Z-axis and THEN rotate along the Y-axis it again rotates over the world's Y - not the shifted local Y-axis with a new orientation after i rotated over Z. What I basically need is taking the newly oriented "local" axis into account - the Y-axis should always point upwards from the upside of a cube. No matter how the cube is oriented. I hope you guys know what I mean... i attached an image to clarify. Also I attached a very simple example with 3 Attribute VOPs for rotation over each axis. No matter how the cube is oriented, it always rotates over world-axis. Maybe somebody can point me in the right direction? testrotation.hiplc
  17. I have searched the web for an example on how to use the Rounded Edge VOP http://www.sidefx.com/docs/houdini/nodes/vop/roundededge.html [www.sidefx.com] But was unsuccessful. I have a 3D model which is very reflective and has sharp edges. It looks dark in the environment, because the edges are too “perfect”. I want the edges to be rounded just enough to catch light and reflections. Can any one provide a simple example on a cube? thanks
  18. Lately I have been trying to wrap my head around transforming point positions with the use of matrices in VOPs. To do that, I tried the following: Lets assume I have 3 points with their position vectors A, B and C which come from an alembic and are constantly changing values. I use a time shift and set it to $F + 1, and extract the same points position vectors, which are now called D, E, F. Then I set A,B and C into a 3x3 matrix, transposing it (to get the vectors in columns instead of rows) and do the same with D, E, F. After all this, I multiplied the inverse of the matrix containing ABC with the one containing DEF (this was not inverted). The resulting matrix was multiplied with new Position inputs, but the resulting transformations didn't match the original ones... What am I doing wrong? Thank you.
  19. Noise in particles

    I sim a particle system, I want to put some nois after sim but Cd color is not baked at the particles, how can I baked it ? does Anybudy have clue ?
  20. HDA | VOP | NormalBias

    Longest Axis, Octant, Boxify, Hexplanar Mapping
  21. HDA | VOP | Bend

    Multi-context Bend.
  22. Noise in mat custom shader

    Hey guys, I'm struggling to understand some things in mat-level custom shading. Reading the manual and watching the masterclass didn't really help. I'm trying to use noise VOPs to drive the color (or displacement ...). But for example plugging a unified noise to basecolor yields no result (as most other noise VOPs, except bump noise). What am I getting wrong? Why do some nodes work, even though I'm plugging a float output in a vector input, and others don't? Thanks in advance. Cheers, Yulyan
  23. Hello All, I'm newer to Houdini, and working to jump into setting up some simple/fast solutions for wrapping particles around a mesh. Not sticking to the mesh, but flowing over. I'm a professional Nuke compositor with general experience in Maya, so will understand most terminology, but certainly completely new to Houdini, so open to all suggestions and breakdown's of the principles. The end goal is to drive a curl noise vortex up in Y, and place geo within the field that the noise will wrap and flow around. I have attached my test HIP file. I've been trying to combine this tutorial's use of the cross product and XYZ distance, with the VDB setup from Entagma's Curl Noise tutorial. Other than there being a good possibility I'm on the completely wrong path for this type of effect, it seems I may be confused on properly using the cross product in the VolumeVOP. The attached file doesn't touch properly adding or multiplying in the curl noise, because I want to correct my issue with the field to begin. Thank you all for your time, patience and help. My Best, Josh curl_noise_trailsTest_003.hipnc
  24. Hello, I was following a tutorial on how to create a sun in houdini, and I came across a technique used to keep advected points bound to the original surface where they were scattered from (in this case, a sphere). For the purpose of advecting the points, it was created a popnetwork with a curl noise affecting the velocity. To keep the points moving on the surface, the instructor did 2 things: -Turn the sphere into a mesh and convert it into a VDB. -Create a POP VOP, with a Volumesample and a Volumegradient, reading from the vdb converted sphere. After this, the gradient was inverted and multiplied by the output of the Volumesample node and added to the original positions, inputing into the new positions. This last point got me lost. The instructor referenced in some abstract drawings the utility of both this nodes, the Volumesample and Volumegradient and I tried to cross check with Sidefx's Houdini documentation but it didn't have that much info on the subject. Can some one briefly explain what is happening inside both this nodes, and their respective outputs? Thanks.
  25. Hello People, I have been trying to produce a Boolean value i.e. 0 or 1,So that i can use it as condition for my (IF Block) in pointvop. But whenever i am dividing Ptnum by 2 using the node modulo is always leave a value of 0. Help!!
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