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Found 54 results

  1. Smoke follow (fast) animated curve

    Hey Everyone, i'm hoping someone could help me with this problem. In a nutshell, i need to move smoke down an animated path, so that it sticks really tightly to the paths animation, but with all the dynamism a smoke sim brings to the table, i.e. nice peeling away around all the edges etc - I have a fairly fast moving alembic curve - cached out with 10 substeps. (may not be needed but there if i do) - I am using pops with curve force to fire particles down the path, so they follow the curve closely. - Then im using the particles to source density, and also adding their velocity into the sim so that it makes the smoke move along the curve. - Im using a high dissipation value so that i can tighten up the expansion so you can really get a sense of where the curve is / maintain the shape. My issues lie generally in 2 places: 1. Where the animated curve is moving the most - the smoke / velocities struggle to catch up and i end up with a hard edge. 2. Where the curve is tangentially facing inwards in relation to the curve, the velocities 'add' the other way, also creating a hard edge. To try and illustrate what im after - if i could animate a regular smoke sim down a straight path and then warp it into an animated spline shape / spline wrap effect, this would be the best way to achieve it, but im really not sure if is possible - hence this approach. I have already tried upping substeps - but it didnt make any difference. My gut feeling is that the problem lies within how i am sourcing the velocity. I will point out that i am very much in my houdini infancy, so my ability to problem solve isn't great (yet!) Has anyone worked on a similar effect before, or does anyone have any tips/tricks/tuts on how to achieve what im after? Any/All help very much appreciated! Cheers, C SmokeAlongCurve.mp4
  2. Brick wall tool works when moving the spline in x and z direction but when moved upwards the rotation of some of the bricks is rotated in a strange way. BrickWall.hipnc
  3. Hi, I'm generating curves... I want with the "Group by range" select say the first point and offset it with $F, I have this done... for all curves doing the same.. But what if I want a random, in a way that offset of selection on every curve is different, I was trying to use primnum, but seems not to work... Do I need some "For Each"? And if so, how. Please and Thanks! Bretislav DontKnow.hip
  4. 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?
  5. Hi all, Is it possible to create a curve or a line from an animated object? E.g if I had an animated sphere, would I be able to generate a curve from its trail or path (instead of creating the curve manually) so that the curve follows it?
  6. Change a curve basis in VEX?

    I'm dealing with curve sampling these days and one thing I would like to is to set curves' basis through vex. But seems such is not possible, if I'm seeing correctly that those prim intrinsics are not editable: I can use indeed the Basis SOP to read the current basis and then edit what I want, I guess I could even pass a detail attribute to this field with a string generated in VEX... But not the most procedural way and doesn't allow specification per primitive. Anyone else been through this? Cheers
  7. Hi, i want to convert a polygonal line (created for test by scatter and add node) into a bezier curve with the freehand method -> all points are connected but the path in between is interpolated. (like if you draw a curve with the curve sop + bezier+freehand option) Is it possible to convert it? - i tried to add it into the curve soptoo but it doesnt change anything. Thank you for help, Phil
  8. Hello, excuse my noobness, but i am looking for a way to translate a bulge along a curve path to deform a tube. I have a tube and my curve, i add a metaball, to which i add a "follow path" constraint. The metaball moves along the path as i advance the timeline. then comes the time i select the tube , then bulge using the metaball as magnet. i now have control on the bulge, but now the bulge stays static and does not follow the metaball's path anymore. How can i achieve this? For my needs, it would be even better if i could just translate the bulge on one of the curve's axis, instead of having it animated over time. Thanks for any help ! Pierre D
  9. I have a feeling this might be a dumb question, but I have been stuck on it for a few days now. Or maybe not so, as I've been looking countless treads here, but none really solved my problem. I've got a really simple setup, pop curve force guiding some rbd objects (I also tried doing it with points and copy stamping after sim to the same result). At a point in the sim the vectors start to point outwards: What I would need is for their direction to be always facing forward as they are at the start: I've had some luck with using pop torque, but still not what I need. I've attached an example file and the curve alembic. RBD_Directional_Vectors_Curve_Force.hip curve01.abc
  10. making primitive from closed curve.

    Hi, I'm Edmund and I'm beginner on Houdini. I'm trying to procedural road and block for city. Is there any way to making primitive by using closed curve or something?(attached)
  11. Hello guys, Is there a way to create to dynamically create curve point custom handles ? I know I can create a simple curve in HDA and export the curve handle to the HDA, but I can't animate the curve position and edit the curve after. The curve node doesn't take account of the transform node, so it's a bit wierd to modify the points of the curve when the result is 100 meters away. Any help would be appreciated !
  12. Create Curve Coordinates from a Line

    Hi, I wonder if it's possible to initialize a curve from a line and be able to modify the curve from the Curve node. I'll explain what I'm doing right now. Of course, it doesn't work, but I'm sure it will help you to understand what is my goal. Fist, I have a Null node called curve_setup. This node contains parameters that controls my line. So, the length of the line and the number of points on the line. Next, I have an Attribute Wrangler node. This node creates the line using the parameters in the curve_setup. At this point, I did some research on the Curve node and the documentation says that I can "use a space-separated list of coordinates in this field to specify points". Then, there's a list of different format to specify different points. There's one format that got my attention. It's the Pn format which "copy the coordinates of point number n in the input geometry". So, I said to myself : "Is there a way to copy the coordinates of all the points of my previously created line in the coordinates of my curve ?". Then I did more research. I learned that the Coordinates parameter is a string, so I have to use expression functions. That said, I learned that there is a expression function called pointlist that returns a "space-separated list of point numbers". Since this function returns something like this : "0 1 2 3 4 5 6 7 8 9", I though that I could format the string and add a "P" in front of every number in the list. Since Pn "copy the coordinates of point number n in the input geometry", It would create a curve based on the line I created earlier and since I can see those points from the Curve node, I would be able to modify those points using the Curve node handle. Now, I just need to learn how to format the string within the Coordinates parameter of the Curve node.
  13. Edit a Curve Outside an HDA

    Hello guys, I have a simple question. It is possible to initialize a curve in an HDA and give the user the possibility to edit that curve without jumping into the HDA, select the curve node and modify it ? If so, how may do this ? Thank you !
  14. Align a Curve to a Line

    Hello, I'm working on a school project and I need to align a curve to the end of a line both in position and rotation. My goal is to be able to create a curve, anywhere in the scene, and snap the start of the said curve (point 0) to the end of the line. The end of the line is extracted with a carve node on the line itself, so nothing complicated here. So far, I've been able to simply copy the curve onto the end of the line, but it only work with the position of the curve, not the rotation. It's important to note that I purposely created the curve in -Z axis. I know it will work if my curve is properly aligned in the Z axis, but I want my asset to be the most fail-safe possible. That said, It would be very appreciated if someone could help me with this issue. There is a attachment showing my current network and what it looks like in the Scene View. Thank you !
  15. Hey magicians, I've got an alembic walk cycle cloned on a curve that I need to offset the points in order to make them look like walking forward, its probably a dumb question but I can't figure out how to offset the points. Line sop has offset so I thought I can just deform this with a noise and offset that, but how can I offset points on a hand made curve like this? Something like this Thanks!
  16. Move curve point with Vex

    Hello everybody, before anything I'm going to introduce myself. I am a Belgian Technical Artist working in the game/interactive software industry from some years now. I was more a environment artist after my studies, but moved to development with Unity, Unreal and native C#/C++ software development. I began to learn Houdini one year ago and having a developer background, it was more easy for me to understand how Vex is working. I now try to use Houdini at work to improve our production pipeline with Unity and Unreal. Mostly using Vex. And it is a wonderful tool. I am currently working on a river tool with heightfield and curves. I first put the curve on top of the terrain then resample the curve and project each point on the terrain with the intersect function. (I also remove points that are outside the terrain) @P.y = getbbox_max(1).y + 100; vector p, uvw; int isIntersecting = intersect(1, @P, {0,-10000,0}, p, uvw); if(isIntersecting == -1) removepoint(0, @ptnum); else { @N = @N; @P.y = p.y; } The problem is that a river always flow from top to bottom, but the projected curve on the terrain sometimes go up and down. To fix that I loop through each points and check if the current point height (@P.y) is higher that the previous point height. But it is not working as expected. First try with Point Wrangle Run Over Points if(@ptnum > 0) { vector lastPointPosition = point(0,"P", @ptnum-1); if(@P.y > lastPointPosition.y) @P.y = lastPointPosition.y; } Second try with Point Wrangle Run Over Detail(only once) int ptNumber = npoints(0); for(int pt=1;pt<ptNumber;pt++) { vector currentPoint = point(0, "P", pt); vector lastPoint = point(0, "P", pt-1); float currentHeight = currentPoint.y; //printf("%s %s\n", pt, pt-1); if(currentHeight > lastPoint.y) { vector newPos = set(currentPoint.x, lastPoint.y, currentPoint.z); setpointattrib(0, "P", pt, newPos, "set"); } } What am I doing wrong ?
  17. cloth follow the curve

    i need to generate nice smooth silk ribbon that float in air with control of the motion. and i want follow curve i need to generate nice smooth silk ribbon that float in air with control of the motion. and i want follow curve . use ncloth in houdini. Let me know how please. 1, i need to generate nice smooth silk ribbon that float in air with control of the motion . 2, i want follow some curve. little advice is okay . Somebody help me.
  18. I have a curve where I used the parallel transport algorithm to transport the normal along the curve and then I use this curve as a follow curve fora bones chain. My question now is how can I setup up the twist along the bone chain and also make it twist beyond 180 degrees without flipping? (see attached file below) any guidance and examples will be greatly appreciated. Thanks. parallel_transport_curve_framing_03.hip
  19. I created a Curve SOP and used float parameters on a Null to control the curve's points. Strangely, when the float values are (rounded to) integers, the curve's points are located incorrectly. Attached short video demonstrating the bug. 2018-05-05 15-09-13.mp4
  20. I try to visualize a traffic simulation - therefore I set up a emitter particle emitting box in the poppet and a popvop that makes curves attract particles. They should also follow the curve tangents - that doesn't really work. And the really weird thing is, that a lot of particles are being dragged towards the origin. I am a total beginner and would be really thankful if someone could help me. Its for a visualization for my master thesis. Thanks a lot! curve_attract-follow.hipnc
  21. I'm trying to build out an idea for an HDA that would create a vine along a surface based on a find shortest path SOP and some controllers for where the start and end points would be to control how long the vine is. This is mostly intended to be a tool in a realtime engine with the idea that it would be cooked into a static mesh (so it doesnt need to animate). I have the main branch generating fine but I am attempting to create some branching points from the main curve to create child branches from this main branch. However, I'm fairly new to Houdini and kind of stumped where to go from here. Currently I'm scattering points from the main branch and attempting to drive them away from the main branch while following along the surface normal of the underlying mesh. I've got something really basic(just sending them out at a random vector direction and snapping them to the surface) but I feel as though this method doesnt give me any control. I thought about trying to make the branches use a find shortest path as well but Im not sure how to control where the start and end points would be procedurally, hence why I was trying to create curves along the surface normals in an attribute wrangle instead. I attached a .hip file for anyone willing to take a look. Thanks for any advice, I appreciate any pointers in understanding VEX better. IvyGrowing.hip
  22. Polygon to curves and sweep tools

    Hello ! I'm trying to make sweeps from geometry input, basically a wireframe of a polymesh to use in game engine. Unfortunately I got strange result from ends SOP, duplicates lines. Is there a cleaner way ? Thanks ! PolytoEdge_001.hipnc
  23. convert curve to edge selection

    Good evening to the best forum in the world. got a little problem I need an extra pair of eyes on.. I have some geo I would like to lay out UVs for. I have used the shortestpath node to create curves of where I would like my seems to be created. now my question is, how do I proceed? I am not really familiar with the uv tools in houdini. I think I would want to convert my curves into edge selections on my mesh (which I am not sure how to do), and then from there use somekind of uv node specifying my edge selection groups as seems to flatten it out. any ideas? Cheers
  24. Twistet Stripe / Tape

    Hey guys, I'm trying to create twisted stripes / tapes like on this picture. I'm a beginner and know how to create a stripe out of a curve, but how can I twist it in a certain area? Is there a way to make it procedural? Thank you very much
  25. Fluid Follow Curve

    is there away to control the force along the curve want the force on the end of the curve is much higher than beginning of the curve, iam using Cruve to drive it by curve force, btw curve is not converted to poly or Volume hipfile Fluid_Juice.hip
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