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Found 195 results

  1. So when I started migrating to Houdini a couple of months back, I really didn't get into the really simple stuff in POPs because I just didn't think that would be a problem - now it turns out that what I thought would be really simple really isn't very simple at all. or perhaps it is and I'm just too stupid (or too locked into my TP/Pflow thinking) to see it... Lets say I have a couple of particles shooting out from one point and I want to have particles "spawn" of these particles at random frames, inherit the velocity but shift the direction a tad. Final step is just have all points create trails using a POP Replicate to spawn stationary particles - but that part I get fine. Oh, and solutions using VOPs, wrangle nodes etc. isn't an issue, any solution will do. So we're just talking about creating simple growth pattern, something that is ridiculously simple to do in TP or Pflow in Max. Like this setup I did in TP 1-2 years ago, the secondary growth patterns.
  2. Points as force in RBD

    Hello, My name is Atilla. I'm a new member of this forum and also new in Houdini. I wanted to introduce myself as it is my first post here. I made a pop sop which includes some particles spawned from a sphere and gave them an outward velocity. Now what I'm trying to do is using them in a basic rbd setup containing a ball and drive the ball with those particles like it's exploding. I've searched the forum but because I'm new I think I coudn't even search for what I was looking for . Can anyone show me a way to do so. Thanks;
  3. POP forces and Bullet sim

    Hi everyone. I've come across a little hurdle, that I'm sure must have a simple solution, but I can't quite figure it out. I've created a simple scene to illustrate what I'm after (see attached). Basically I'm using the POP Attract force to drive the animation of my RBD objects (I'm using the Bullet solver), and I'm getting the result that I'm after. My predicament now is that I want to vary the effect of the force on a per object level. So in reference to the example scene I've attached, have the torus objects be less effected by the attract force than the teapot objects. Like I said, I'm sure there must be a simple solution for this, and I'm hoping one of you clever people can point me in the right direction. cheers! bulletAttract.hip
  4. Trouble with debris shelf tool

    Hi All, I'm relatively new to Houdini and I'm working on a destruction sim of a car hitting a crystal/ice statue. I'm really close to getting a result that I'm happy with but I've hit a brick wall trying to get a fine spray of particles as a secondary effect. Here's what I have done so far: 1. import statue GEO and use a combination of cookie SOPs and Voronoi Fracture to pre-divide the mesh into groups. 2. create an RBD sim using the RBDglueObject node, bring in the low-res car proxy and use it as a collision object. 3. smash car into statue. 4. cache out the RBD as a .bgeo sequence. 5. read in the cache and everything works fine! 6. press the debris shelf tool, this is where things start getting confusing. so I'm getting several odd results, firstly I have to run the sim from frame1, despite having set the debris_sim node start frame value to the correct frame (512). I'm also really confused about the relationship between the constantBirthrate attribute of the POP_replicate node and the constantBirthRate attribute of the POP_source node. My end goal is to use the particles to instance some very simple geo with a copy SOP, however when I do this I find that where I thought there was just one particle, there are actually a load of particles, all occupying the same space, resulting in loads of copies of geo overlapping each other! I haven't uploaded a scene file because my scene is a little heavy but if anybody needs one I'll upload a simplified version with the cache as a .zip Many thanks in advance and any advice or help at all is much appreciated. M.
  5. Bottom of Sim Pops

    Hello. has anyone run into this problem before? the flipbook looks perfectly fine. When it comes down to the render though, theres a small jump on the base of my smoke. its subtle from where my cam is, but i want to know whats causing this. ive tried disabling auto resize, disabling all lights, the rest fields, played with volume quality, shadow quality, i think every parameter in the mantra node (micropolygon rendering), raised substeps in Dop, removed all keyframes in the shape tab and in the source noise, disabled collisions with my ground... the only things i can think of it being, is the enforced boundaries of -Y? but how is this debugged/fixed? X_X id really appreciate your help. im beat. the attachments rendered in alpha and cropped. no rest fields here either.thanks in advance. Smoke_pops.rar
  6. POP H13 Self Collision

    Hey everyone, I know this question has been asked before but I don't think the answers have been really satisfying. So here it is again: I'm trying to create a self collision effect like the way that nParticles do so easily (see link below) http://youtu.be/gfkDZQD-Hbo I'd like to be able to do it without RBD or FLIP, just by using the new POPdop, because I know how to do it in the old pop but it's quite slow and I like the new POP system much better. It'd be great to be able to consider the radius Per Particles so copy stamping could be simplified. I think it could be even used to make snow/sand sim. Would it involve writing some codes in a wrangle POP? Thanks everyone for helping
  7. cell animation Pop&Dop ?

    how can I realization appending mov feeling.? please give me a tip & work process ㅠㅠ Microbiology-HD.mov
  8. Hi, everyone. I have a pop, there is something not working right. I take a sopsolver in new pop, initial a "s" attribute to 1, and then jump in sopsolver created a pointwrangle with f@s +=1; But it just increase once, then not increase at all. I just begin study the pop. Any help will be appreciated. Thanks. pop_sopsolver.hip
  9. Hooke's law

    I am trying to create a basic particle system with spring-mass constraints based on Hooke's law with the aim of creating some granular simulations. I am still learning Houdini so i'm just trying to assess the options to achieve this.. Could I just use a popWrangle to update forces and velocities inside a popnet? Or would it be better to use gas microsolvers? The ultimate goal is to achieve this!: baby steps first though..
  10. Hi everyone! I'm working on a project and I'm trying to create a custom life attribute for a group of particles. I've created a particle groupn using the random option and created an attribute node called "life" as a float type and a value of 0.2. But it's not working. Any ideas or suggestions will be appreciated! please find attached the file, colour_force_group.hipnc
  11. Hi everyone, I need a little bit help. I want to scale by velocity an rbd packed object drive by pop and keeping collision between objects. I want all the cubes collide each other and keep scaling based on velocity. To be more clear i've joined an exemple file from Next step procedural animation. Thanks for helping. pop_bulletforce_scalebyvelocity_400.hipnc
  12. Pop align to ground when hit

    Hey all, I'm playing with Pop to create a confettis setup. I had some difficulty to figure out how to make particles align to the collider object when they hit. I did some test with a vop pop and playing with orient attribute but I had problem mixing 2 orientation together, the vop node is still there but inactive. I've linked a scene so if someone can have a look, that could be nice. Thanks Doum Confettis_falling.hipnc
  13. Hi All, I'm currently facing a simple problem: Does the POPs object able to collide with Packed fractured objects ? Attached is a simple file all created by shelf. I thought it collides by default but not. The only way came up to my mind is to unpack the packed object and make the POP simulation inside another DOP, collide with unpacked SOP. Houdini 13.0.288 Thanks. popCollisionWithPacked_H13.hip
  14. Hey guys, I'm trying to create an effect, where spheres move from the centre and after a certain frame, they all fall on the ground after each other. I've created pop net which drive the movement of spheres. I've tried to achieve the falling of spheres in two ways: 1., force and collision in popnet - works nice, but the rotation looks funny when colliding with the ground + I can't come up with a way, how to make the spheres fall after each other (so they don't just fall on the ground at the same time) 2., rigid body for spheres - I can't find a way how to mix the velocity from pop with rigid body. What I did was, that put a switch node and after a given frame - pop driven spheres are invisible and the RGB spheres become visible, but I suppose that is a very nooby way of doing it There is a visible difference between these two ways, because the popnet driven spheres fall down nicely and the fall looks more natural. With RGB spheres you can see when the movement is switched. Is there a way how to take the velocity form the popnetwork for each particle driving the sphere and blend it with the RGB simulation somehow? Or in other words, could I make the rigid body simulation of spheres make look like the one I created with the popnet? Sorry if there already is a topic explaining this problem, but I wasn't able to find it yet. Thank you RGB_POP.hipnc
  15. Useful Pass for Particle effects

    Hi everyone! Am working right now on a shot. It's a sort of ink effect with a mix of millions of particles and wispy smoke. Am pretty PEON to particle rendering and I was wondering if anyone could tell me what are the most useful pass for particle effects. For the moment, the pass I will use are: -Beauty (constant shader) -Depth of field (grayscale) Technique based on this thread -----> http://forums.odforc... field__st__12 -Age (grayscale) -Shadows (still searching a good way to fake shadows) -RGB(3 lights) What is the best way to use this pass? Do I have to use those three channels separatly as a Mask? What are the most useful pass for particle rendering? Thanks ODFORCE.
  16. Hi! I'm trying to create a leaves generator to attach to a fluid simulation and I'm doing this way: Create a particle system, create the geo (planes) with the copy sop, import it as cloth and then make it work with the existing pyro simulation. It work well, but I have a problem: I can emit particles just the first frame, otherwise the cloth give me an error, as the initial geo has changed. How can I emit particles/geo on every frame I need? Other point: is there a way to pass the particles ID info to the cloth object, so I can vary the mass attribute per object?
  17. Have been searching around a lot on Google and don't find a working shader that works for particles point color and point alpha. Only one I found is the Clay shader in 12.5, I got this working. But it doesn't have any Specular or Reflectivity. Not skilled enough yet to make my own that does work. Newb. Anyone who can help? Thanks M.
  18. Today I compiled the POP_Circleforce( which is in HDK samples/POP/ ), but the node has no effects to particles. Later I found the problems is that the function "checkActivation" always return 0. I checked the hdk document. There is one line that says: "checkActivation() returns 1 if the POP should be active and 0 otherwise.",which does not make sense to me. Finally I removed this function from .C file and the node works well now. I am wondering if any one know what the function actually means and when we need it in POP node. Thanks
  19. alternate version for particle wave

    Hello all, I'm using Peter's great Tutorial "particle wave" as reference but I'm not trying to replicate it. I'm using a vopop to add $CR value to the position of the particles, but it look like the particles are NOT going back to their original position( 0 in Y). what am I doing wrong? thanks for any help or link to previous post.. EDIT: if someone can think of a better way to do this, without pop, with an attribute transfer, a vopsop...anything, that would work too. I'm mainly trying to get the bar to scale up in Y. They will drive something else later. curve_wave_01.hipnc
  20. I am nearly there with this system. I have been able to get the points to run the circuit around the turns as long as i start them from the prim center, but when I switch it to start from random surface points so the points are varied, there seems to be some issues with my calculations. There are two nodes in the network that are giving me trouble, both are attribute nodes. The first is simply trying to map an attribute that I calculate in a VOP POP to a local variable, something that I shouldn't even have to do, and have used elsewhere in the scene successfully, but this particular variable is being pesky. It will work for a few minutes, but then break without any modification to it. It is being unstable and I am unsure why. The other is a node that calculates the point at the center of the turn so I can get a turn radius and radial velocity further down the line, but it seems to be grabbing the wrong points and I am struggling with figuring out why. The calculation should work logically, as long as the previous attribute does. I have turned the two nodes with problems red in the POP network inside the main SOP. Anyone with any explanation for this behavior would be welcome. city streets fullTurns.hipnc
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