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Found 46 results

  1. 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
  2. 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)
  3. 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 !
  4. 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.
  5. 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 !
  6. 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 !
  7. 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!
  8. 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 ?
  9. 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.
  10. 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
  11. 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
  12. 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
  13. 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
  14. 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
  15. 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
  16. 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
  17. 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
  18. I have a curve with 1203 point , and now i want to resample it to exact 800 point , is there any solution for this ? i want to use it for polypatch or bridge between two curve , currenty i have lot of error after polypatch/polybridge , because there is difference in point number between two curve. thanks
  19. Extrude along Curve

    Probably the mother of all dumb questions but how do I extrude along a curve properly? I've tried all the options I can think of in the polyextrude node.
  20. I am trying to mimic a rail spline like you would use in Cinema4D. Essentially I would like each point normal to look at the point with the same index on another curve. From what I've found on getting a direction from two vectors is to simply subtract B from A. However, this does not seem to be the case. (See attached file) Is there more to it than simply subtraction? Align_Normal.hip
  21. Hey guys, Kinda Intermediate at Houdini and a recent full time convert from the 3DSMAX/TP world. I have been working on a tool, where the user can easily plug-in curves and generate art direct able particle flow along the input curves. Its about 90% done, and it works great with curves that are not too close to each other or don't intersect each other at too many points. How ever in certain scenarios. like multiple inward spiral curves intersecting each other, since the POPVOP system is based on Particle Cloud Search : - PC Open to look for particles close to the curve points. - Use those points and push them along the length of the curve using the curve tangents. , the particles get attracted towards either curve based on the search radius and no. of search points. This is definitely understandable, on why its happening. But is there any way to lock/tie the particles to specific curves only? The Radius and No. of Points parameters give it a lot of control for most scenarios, but the one mentioned above. Obviously there are a lot more parameters that i have added for dictating the flow behaviour. But the main solution that i can think of is to have the “found” particle only follow the curve and be affected by the parameters along that curve ONLY. Maybe have a POPVOP decide groups for the curves/particles? TLDR; Need to make the particles only flow along the curve it chooses/gets attracted to at the beginning. I have never worked with groups in POPNET, so im pretty much lost. Unfortunately because of my limited knowledge at Houdini i haven't been able to figure out how to achieve this. Would really appreciate some help on this.
  22. Hi all, I'd like to animate the progression of an L-system like curve, similar to how sliding the generation parameter works. I thought the carve SOP would be the best approach but each primitive's U value starts at 0, causing all the curves to draw from the start. Is it possible to modify the U value of a curve, so that each prim can start at the same value of the shared vertex (where it branches), or can I carve by an attribute? One idea is to duplicate the point where the branch splits on any secondary branch, enough times so that it offsets the order of vertices to be in time with the main branch - I will try to implement this in the meantime Attached is an example file to help explain lsystem_carve.hipnc
  23. Hello, I'm new to Houdini. I am trying to get particles to follow a curve and end up filling a bottle but I cannot get the bottle to fill or the curve to work effectively. I've tried a bunch of different things but the closest I've gotten is with these two files. I used an OBJ of a bottle and turned it into a VDB. In the first file (particle_flow_v07) I used a popnet to get particles along with a popcurveforce to flow along a curve into the bottle. It looks like it worked ok but the bottle doesn't fill up all the way. I thought it was because they are particles and not flip particles but was unsure how to convert them to flip particles. In the second file (v13) I tried using a sphere as a flip fluid emitter instead. The particles follow the curve ok, some of them fly off the curve even though I increased the force of it; and the particles that end up in the bottle only fill it to a certain point then they just spill out everywhere. I tried modeling a funnel to get more particles in the bottle but it didnt seem to work. in v13 theres also a torus I was going to try to use as a sink object but I couldnt get it to work correctly. Any help or advice would be very appreciated. EDIT: So I tried a bunch of tests and I still get the strange purple collision box through my ground plane; not to sure what that is; maybe its the particles colliding with the ground plane? The particles flow along the curve beautifully so thank you for the tip about my particle separation. Particles are still leaking though my geometry and I have a bad feeling it's because of the obj I found online but I am still unsure. particle_flow_v13.hipnc Glass Bottle.obj particle_flow_v07.hipnc
  24. is this possible to make this curve with expression ? tnx
  25. Spiraling curve from curve

    Hi guys I'm new here. First of all I wanted to thank you for having such an awesome community. I'm pretty new to houdini, but have learned a lot by lurking on this forum. I would like to create a spiraling curve(like a phone cord) from another curve(not a straight curve). I already saw some other solutions by just making a helix and deform that along the curve. I also saw a solution about making an arc and sweeping that on a curve and later join the pieces together. I was wondering if there would be a more procedural/mathematical way by using the curve and a point vop or point wrangle? Maybe with a cross product and using the point number as a variable to control the twists? Unfortunately my math knowledge is pretty basic. I would be very happy if someone could post a sample.
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