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Found 195 results

  1. Ok, so this is about me (and anyone else interested) learning how to manage particles in groups/streams and I'm going back to the type of growth I've done before, stacking POPs, but never managed to get working in one single POP network. Basically, the groups and/or streams just don't act as I expect them too, I just don't "get it", how the streams/groups are handled through the solver cycle... So this is what I came up with, because if I understand how to set this up, I know I "got it" - so to speak. Here's the "rules". Blue particles are born from the orange input point on the first frame. Blue particles create a trail of red, static particles. At a random interval, blue particles replicate a pink particle. Pink particles create a trail of green, static particles. Pink and blue particles avoid the static red and green particles. Pink and blue particles also travel through a noise field. The noise doesn't affect the red and green particles. Oh, and the colors aren't just descriptive, they should have these colors. And it all seems so simple - if I still was in Max, I'd be able to set this up in PF or TP in 10 minutes - but getting this going in a single POP, I can't even get half way before it "breaks", thus the very basic hip file. No reason to supply the 15 ways I failed to do this... splittage.hipnc
  2. Particle velocity based on age.

    Hey guys. Quick question here. I have a simple particle sim emitting from a sphere in a direction. I want the velocity to decrease as the particles get older. how would I be able to achieve that? Some of the particles are already born at frame 1 (I have a preroll on my sim) and this needs to apply to them as well. Thanks for the help, and thanks for an awesome forum. Cheers
  3. Hey guys, first post here. I'm extremely noob at Houdini and I've got a very basic question. I've got a particle system going, and after the POPs system in the Source Particles SOP it creates, I'm trying to use the Y position of each particle to drive a Blend Sequence that is copied onto the particles with a Copy SOP. What I haven't been able to find is how to query the Y position of my particles. I can find their positions with the Geometry Spreadsheet, but the name of the attribute it gives me is "P[y]", and typing that into an expression doesn't seem to work. I had thought it might be "@P.y" but that errors out as well. I think one of the problems is that I'm not telling Houdini WHAT to find the Y position of. But again, not sure how to find that. I've googled and did a cursory search of the forums here but all the posts I've found are way more advanced than this simple thing I'm trying to find Can you fine gentlemen/ladies point me in the right direction to find how to query this sort of basic data? wk2_copy.hipnc
  4. Hello guys, I work whitewater for splash. I made a whitewater source particle. I want high velocity pariticle delete. So I made a high velocity group made. However, The pariticle are removed from the group while slower speeds. For example is parabolic movement. But If I want to continue to maintain, including once in the group based on the ID. I try it use sop solver. but point count changes does not work. Is there any way what? Many thanks, Hyungi Jeon.
  5. Hey guys quick question, I need to do some operations on two particle streams\groups using point cloud using a pop vop. fist of all, can I put the pop vop after merging the two streams, or do I need to have it connected to one of the groups before the merge, and how to plugin the two in the pointcloud open? Note:I'm really new to pointcloud, but I've been using TP witch has the same method of groups and searching between the groups! Thanks, Mook
  6. Hi all! I have a problem with point normal. In my scene I have a voronoi fractured object represented with one point per fracture. I simulate these points with POP sim, but I can't give a normal direction that follows an (alembic) animation (It's difficult to explain) I attatch two screenshots and the basic scene. Thanks in advance! Test_particles.hip
  7. Hi everyone! I would like to share our student short-movie, we done all the FX with Houdini and some render as well. (PDB, RBD, Smoke, POP Particle) link : https://www.youtube.com/watch?v=7HS6V0S7YbM We would like to thank again all the people who helped us accomplish our goals and make this short film. Without them we would never had won so many prizes (12 nominations, 3 prizes, broadcasted on canal+ & Futuroscope)! Thank you to OdForce, Houdinimatic, Houdini Forum and a huge thank you for the free licences that were provided Houdini We would never be able to do this movie without you! Fell free to share it !
  8. Hi Folks! This is my first post here! I'm returning to Houdini after a break only to find that POPs have changed a lot... I'm stuck on one little thing - POPspin. I have a very simple AutoDOP network - (location - POPsprite - POPsolver) in POPsprite I have a VEXpression (spriterot = rand(f@id)*360) which sets the sprite angle to random. I want to give each sprite a slight random spin which I have tried to do with POPspin but I have had no joy! Should POPspin come before or after POPsprite? (at the moment neither works...) Any help welcomed, Thanks S.
  9. Having an issue with a gap in my Popcurveforce node. Using a basic nurbs curve Circle. Sliced Arc seems to give me the best result but I'm still left with a little gap in the Influence Radius. Any ideas why? Thanks guys
  10. Hello Everyone! I have a Pop source followed by a pop group; i need the number of points contained in my source group to be stored in a variable that i am using in a fit function. npointsgroup function returns 0, (tried also with the npoints function) what am i doing wrong? int npts = npointsgroup(0,"stream_chunks"); float ptprog = fit(@Frame, ch("s_frame"), ch("e_frame"), ch("s_value"),npts); ingroup = (@id>ptprog); PS_i am trying to print the value but also this seem not to work //void printf("npts= %d", npts); Thank you in advance!
  11. Hey everyone, I originally started this thread on the sidefx forums here, but I'm still stuck on how to proceed with this effect. My initial goal is to get particles flocking by color. Once I have that figured out, I need the particles to also flock around a goal geometry so they can take its shape. In the end I'd like to have blobs of colored particles oozing/crawling around the geometry's surface. I've done some research on flocking concepts, so I know that I need to create alignment, repulsion, and attraction forces to manipulate the particles, I'm just stumped on how to execute the concepts in Houdini. I have the cmivfx tutorial on flocking, but it looks like some of the SOPs have changed with the years... preventing me from finishing the tutorial In my previous thread I was introduced to the pop steer nodes, but they're lacking sufficient documentation/example scenes so I'm having trouble getting started with them. I think using those nodes with VEX would be the best way to do this, but I'm open to anything to get me started! Thanks! Mike color_and_shape_flocking.hiplc
  12. Pop Land

    Hi, just a small question,how can i make the particles land nicely in the target geo?,i mean they keep jumping around Thanks! LandQuestion.hipnc
  13. Hey, First off, thank you for taking the time to read this and help me out. I am a bit unhappy with the flexibility of the Voronoi Fracture Configure Object node (from Make Breakable), so I found this: From what I understand, he is piping the first-fractured pieces through a foreach node, adding a centroid point - all done. My problem is figuring out how that centroid point can be divided into more points (eg. by time), thereby also re-fracturing the current piece into tinier bits. If I didn't explain something properly, please do let me know. Thank you!
  14. Hi, first of all sorry if this has already been asked. I'm advecting some particles from a pyro sim. I would like to transfer some attributes from the pyro sim to the pop sim, like density, color, other... I have to use the gasfieldtoparticle node if I'm correct, but I cannot set it up correctly. Here is my DOP network I don't really know the correct way to use this node, could you please enlighten me ? [another question out of topic, do you use win10 on a work machine and do you recommend it?] thanks a lot!
  15. spheres copied on points collision

    Hi, I am stuck in a weird problem for one of my project. In fact there are 2 problems: 1) I have a source from where points are emitting inside pop. Outside pop, using copy sop spheres has been copied on per point. Problem is spheres intersect each other when they collide. How to use collision in this case? 2) When points are emitted they tend to align with them selves so they look streamlined. How to break them so that they look little scattered not so much but little just to give variation? Thanks.
  16. Particle control and render passes.

    Hey Guys, My deadline is coming up and I have a few small problems that I quickly need to resolve. 1. I have a snow covered car. The snow falls off the car to reveal a new body-paint color. The source is a pre-constructed, scattered and point-replicated point cloud on top of the car geometry, revealed based on input particles from falling snow. (I used attribute transfer with a solver node for that) Everything is working fine, except of course that all my particles are dropping from the car, simultaneously. My question is; how do I start them off "frozen" and have them fall based on my input? I was imagining an animated noise pattern so control the activation, of sorts. But maybe an animated metaball setup? I am just not sure what particle attribute to use. The "active" one doesnt seem to do anything. 2. Ideally I would like this snow to be grains, so that I can have clumping and stacking, but since I am colliding with car geometry, the grains always explode. Is there a way to maintain constraints without everything exploding? I am using a vdb collision volume sample of the car. It looks like Houdini automatically adjusts the particles so that there are no intersections with the collision VDB, but I cant seem to get away from the explosion. 3. How the hell do I get geometries with a shadow matte shader assigned, to not cast shadows on one another?! but only from objects that are NOT a shadow matte? I am basically just trying to render this snow out in two passes, and one is a shadow pass. I only want shadow from the snow, affecting my ground and the car. But no shadows from the car affecting the ground & vice versa. Much like Vray's material wrapper. 4. I have 6 licenses but have not yet set up HQ server. Could anyone briefly explain the process of getting this setup? Thanks so much for any help and input! // Mats www.swedeballs.com
  17. Hello, CONTEXT I have a scene in which a character is painting a floor. The paint is transferred to the floor as points and converted into a VDB and then geometry (to fit the style of the film). Here's a video of the scene I'm busy with: QUESTION It would be nice to get some secondary splashes when the character slams down the brush (and randomly when he paints on the floor). My initial thought was to source the brush geometry, and give it a pop collision detect (for the floor). Then replicate the points with an initial velocity, mesh them and presto. A couple of problems though: 1. I want the particles to emit only now and them (randomly essentially) and at high impact times. 2. I would like to set the directions of velocity to match the animation. 3. With the pop replicate the shape of the splashes wouldn't look ideal The scene and its alembics are a bit large for the post :/ Thanks
  18. Drag in one direction

    Hello, How could I go about having drag only affect one direction? I basically want my particles to have drag equal to their velocity (airresist *= length(@v)) but only if they are moving up. If they are moving down I don't want them to have any drag.
  19. Hi guys, I'm relatively new to Houdini and I'm trying to find a fast and easy way to add mist to the already great off-the-shelf wave tank. I have found one video so far: He seems to be adding particles via POP over the surface and deleting geometry with the color attribute. Unfortunately no additional information is given. Any houdini veterans out there that can reverse-engineer this system? Any help, information or examples is greatly appreciated .
  20. Foam tool Creation

    hi all houdini user... i am impressive about this foam tool when i found this link.. i start to archive that fx in houdini...and start to research for these kind foam FX. then i try to make these SOP setup with metaball on ocean grid and i think thats good for start point.. but ends up when I have problem to continued the the foam because the ship is tracking with metaball so, is there any one could help me how these metaball following the shipa and animated ocean grid.. thanks.. i so much appreciate for these one fx..thanks heres's the hip file and FX references.. foam_tool.hipnc
  21. R.I.P.D DeadoDeathFX

    Hello, Not sure you ever stumbled on this work of mine but I wanted to post this anyway. This work didn't make it into the movie the way you see it in the video and although its been inspiring and helpful for other artists to accomplish the director vision it's pretty much remained a solely piece of home work And so I'm sharing a hip/bgeo file of what I did in my spare time before I took it further at work. With the hope there will be something useful in there for anybody here willing to give it a try. After all, sharing is caring! https://vimeo.com/106126363 Alessandro
  22. Hi guys, I've hit a bit of a wall in the new version of POPs. I have a deforming mesh (skinned character), which I have scattered points on. What I'm trying to achieve is a set of particles that are essentially locked onto their source point until a certain time or proximity from some sort of gizmo, and then morph to the position of another set of points. I have been able to achieve this in the old version of POPs using a position node, but it's rather slow. However I can't seem to figure out how to achieve the same thing in the DOP version of POPS. Any help would be great appreciated. Thanks
  23. Hello everyone, I am trying to create an effect for a project where particle is moving in a tube with constant speed. What I need is to particle gets slow down at crushed cross section (shown by red arrow in image ) and then move ahead at normal speed. Any pointers to achieve this will be helpful. I have attached a reference image to get better understanding. Thanks in advance.
  24. Pyro field to POPs

    How can I colour particles based on pyro fields? E.g. colour based on temperature/heat. I'm guessing gasfieldtoparticles? But I don't have much experience with microsolvers and not sure of the setup.. Thanks
  25. My second question for the day in regard to POP's. I'm splitting them in different threads as they are simpler to find for others looking to solve the same problem. So, I'm looking for a solution to spawn particles in all directions with constant speed, like a shockwave, be it a growing spherical form or for creating something like a ring growing on a surface. And yes, I can easily create velocities in VOPs for a point and use it in POPs but I'm looking for an in-POP solution, say you spawn particles from another (using POP Replicate) particle or a collision. Now, you would think it would be as simple as creating a VOP and just putting a constant to the velocity, but noops. Also, why is that? That should just work, imo, or am I missing something?
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