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Found 48 results

  1. Well, I went out into the RBD Constraint Forest Unprepared, and now I am lost in the woods. Any help would be appreciated. I'm trying to do something that should be fairly simple, and most likely is, but I don't have the combination to the Houdini lock to get the setup to work. In the example file I have an rbd box that has 10 faces per side that have been made into unique faces. They have glue constraints holding them together and are a rbdPacked object in my dopnet. There is a low rez smoke sim that pushes this rbd box into a collision sphere that is above it, and when the geometry collides with the sphere, some of the glue constraints start to break. All I wish to do is apply either a gravity force or a popForce to these rbd pieces that have lost their Glue constraint. I want the main chunk of the rbd box that still has a bunch of pieces glued together to keep on moving with no gravity or popforce. I might be trying to go about this the complete "wrong" way since I have very little experience with Glue constraints, But I see data in the geometry spreadsheet while in the dop net called ConstraintGeometry and this has a primitive group called "broken" which contains the glue constraints that have been broken due to collision. I would think I would want to try finding out which rbd piece that broken constraint belongs to and then use that to create an "applyGravity" group of rbd pieces so that I can do what I want to do. I just don't know how to do this in dops. Is this something that needs to be done in a sopSolver or geometry wrangle or....? I'm not to familiar with how to read data from the ConstraintGeometry and apply it to the Geometry data. When I middle click over my rbdsolver, it shows the main rbdpackedobj1 with Geometry and then CosntraintGeometry below it. They are like separate entities and I'm not sure the best way to get access to both in one node, if this is even the way to do it.? For example if I change a geometry wrangle to point to "ConstraintGeometry" instead of the default "Geometry", I can then read and manipulate data on the ConstraintGeometry, but then don't have access to the main rbd "Geometry" that I am use to normally working with. Like everything in Houdini, there are probably dozens of ways to go about this, I tried about 20 yesterday, without ever getting one to fully work. I ran out of search phrase ideas to try throwing at google after about the 6th hour of searching. Maybe using some of those copyData and applyData nodes would get the ConstraintGeometry data onto the Geometry stream so they can both be read in one wrangle or maybe that too is a completely wrong direction to take. I don't want to speculate any further since you could try things for a week and not get it to work if it just isn't the right approach. I love Houdini for its vastness and unbelievable tool set, but man, it can destroy you if you don't know how to do what you want to do, and can't articulate it well enough for a search string.! Thanks for any help. E rbd_constraints_v01.hip
  2. Hello! I fed a simple grid to a voronoi fracture node (fracture points and geometry source both from the same grid object) & it made some pieces. Great! How can I group the pieces in order to use it for a followup extrude node? I want to extrude and slightly inset the pieces... like a brick pavement or stone wall type of operation...
  3. Group rbd packs that broken

    Hi all. i did this tutorial : http://shortandsweet3d.blogspot.com/2018/06/animated-constraints.html now i'm wondering how can i make a group of shattered piece and mask them on some forces. for example in the tutorial, detached pieces don't affected by impulse force. Thanks.
  4. POP Wrangle Group

    Hello, I want a second age ("myage") for particles, when they are in the group "active". Very simple? But it don't work
  5. Vdb grups?

    Hey magicians, I have a setup that make some blobs growth, but I need them to growth in a different speed each one, I tried making groups out of vdbs to control each one by time offset with no luck, also tried playing with different vdb names. Any tip on how can I affect the speed of each blob separatedly? Plan B will be making each vdb growth separatedly and then play with vdb combine, not sure if I'll get the same effect but will give a shot. Here is a sample gif and file to illustrate my issue Thanks in advance! growth_hip_for_offset.hip
  6. Group in dops [SOLVED]

    Hello ! I'm trying to apply a force in dops to some packed geometry based on some rule. For the test, I use a group that have "@P.y<2.5" in its expression box, and use this group inside of a drag node. But for some reasons, it's not working properly. I never used the group node in dops before, so maybe I'm missing something. Not working properly being the force still applied to the geometry, even though the geometry is clearly above 2.5 in y position. Anyone have an idea ? Thanks ! group_in_dops.hipnc
  7. Is it possible to use at point group from sop level, to constraint points in a dop (wire sim) with the "SBD Pin Constraint", instead of manually typing in all the points, that has to be "Constrained Points"?
  8. I'm creating a group from the box sliding over the fractured grid and assign the Color from Black to White in that group. How would I randomly delay setting the color in this example, so it's not a straight line of assignment. I tried creating a random offset when it gets assigned into the group, however unclear how to increase the offset counter per frame, so I can assign a formula in setting the Cd.
  9. Hey Everyone! So the issue is... I am using Voronoi to fracture an object. The inside and outside faces are in two groups named 'inside' and 'outside'. I'm using the 'assemble' node to pack the primitives however, doing this, it looses the 'inside' and 'outside' groups which I need to use later on. Is there a way to use the assemble node and keep the groups? Any advice is massively appreciated! Thanks All!
  10. Group combine pattern syntax

    Hello ! I’m completly lost with group syntax and wildcards. I try to combine every second primitive group. Looked at the doc (http://www.sidefx.com/docs/houdini/model/groups.html#syntax) but it doesn’t help me sadly. Any advice ? Thanks group_problem.hip
  11. new parmTemplateGroup

    i am creating a new HDA with python and unfurtunally doesnt use the parms that are in the subnet, so how can i create a blank new parmTemplate so later on i can add the spare parameters to it? thanks guys.
  12. flip reseed group new particles

    Hi all, I was wondering if there is a simple way to group newly seeded particles during a flip sim. The reason I would like this option is that I have a sim where I'm not meshing the particles but rendering them directly and the seeded particles pop into existence in an unpleasing way, so I was hoping to somehow scale them up gradually over a few frames. Thanks in advance
  13. In older versions of Houdini I could add a point to a group's selection. Has that changed in H16 because I can't seem to get it to happen? Any advice would be appreciated. Thank you David
  14. Hey guys i have an group of edges , i want to make another group and add just one of those edge from first group to it . is there any trick for doing this ? thanks
  15. Houdini User Group on Steam

    If you're on Steam, join the Houdini User Steam Group here: http://steamcommunity.com/groups/houdiniusersgroup
  16. Squashy effect

    Hi node guys! I have a question that i breaking my non-programing head. I have this points selected based in the bounding object, I would like to push them out and make it look like is Squashing against any object in his way. I'm not using FEM because it didnt work in this case, actually dont know why. Thanks for any help or idea you can give me Jason.
  17. Facet SOP ignores group selection

    Hi, i wanted to use the Facet SOP on a certain selection of points. The node network looks like this: The group parameters are as follows and select four points. The Facet SOP parameter are as follows: Every option I select in the Facet SOP (e.g. Make Planar) effects all points and not only the selected points. Has anyone an idea why ? Thanks in advance
  18. Hi I can successfully group unshared edges to get the boundary edges of a flat grid. However, how might I procedurally remove the very inside enclosed hole edges (such as the three holes in the attached image), and only have the very outside perimeter remain in the group? Any advice appreciated
  19. So, i tried something from scratch for the first time, albeit very simple... almost there! That being said i did got stuck up... 1. SOFT SELECTION GROUP: i am trying to apply some animation to a bunch of lines through a pointvop. i want the animation to be limited to all the points but the ones at the ends of the lines, i create a group of those points... it works,- but could be better if i could make the animation blend to the static points at the end. 2. FADING TRAILS: At the end i added a bunch of trails with some lag and or jiggle. i am coloring them with the width attribute through an 'attribute create' node. Is there a way to make each trails less opaque than the previous. (if this can't do the job, any other tips?) 3. NOOB VOP NETWORK CRITIQUE: I am pretty sure my vop network is far from efficient, i would appreciate if anyone has some tips to make it more logical/ efficient. I hope i was able to explain myself. (i have attached a screenshot for reference) d.
  20. By default, when selecting components or make groups, houdini shows those selections as "light cyan" color... but the background of the viewport is almost the same color.. bright cyan. Sometimes dificult to distinguish. I want to change the default selection color to another one(green or orange), but not stablishing them in Group and attributes window. ¿¿Where is the menu or option in preferences to change this parameter?? Thanks in advance.
  21. Can I get a group from PolyCap?

    Is there a way to define a group of primitives based off the faces created by PolyCap?
  22. Custom Group SOP in VEX

    Hi guys, here are the files I used for the last Vancouver Houdini User Group in case anyone wants to take a look. My presentation was about writing the Group SOP in VEX and trying to optimize it. I wrote everything in a wrangle, and it works great as a preset in a point/prim wrangle. I also made a Digital Asset, although it's not a VEX operator because I couldn't figure out how to make it work purely in VEX because I need to use the group bindings from the Wrangle and I'm not sure how to implement that in VEX. Anyways, the OTL is just the wrangle with the parameters promoted. In the presentation file you can take a look at the speed tests of the Group VEX vs the Group SOP. The difference in performance is pretty similar if you have a few points/prims, but once you go above 1 million the performance difference really starts to kick in. The Group VEX becomes exponentially faster than the Group SOP the more points you have. The difference can really be seen when you group by object and when you group by volume. I also made those 2 modes work with primitives. Here are the files in case anyone wants to take a look at the code. Feedback is greatly appreciated! group_vex_jeronimo_maggi.hipnc vhug_presentation_jeronimo_maggi.hipnc group_vex_jm.hdanc custom_group_sop.vfl
  23. I have primitive groups set up in SOP level, something simple like a box with a voronoi fracture applied with the inside and outside primitive groups. How can I access this primitive group in shop context? I am trying to compare whether or not a shading point belongs to a specified group so I can create a mask. I can create a attribute at sop level to store the group information on the points and that works, but I want to do this in the shop context because the geometry will be heavily subdivided and displaced and I need the accuracy. Any thoughts?
  24. Hi guys, a friend was asking if he had some moving points and for example there's a group by bounding box, so some points enter the group for a few frames. Is there a way to delete those points from the entire sequence? I was wondering the same thing myself, so I gave it a go using a SOP Solver. Check out the example file. delete_red.hipnc
  25. POP Group Center

    Hey guys, Hopefully this is a quick one. I was wondering how I could find the average position of a group of particles (and store the position as an attribute on the particles in that group)? Say I have two groups, A and B, and I want to find the average position of the particles in group A and create a force on the particles in group B to go towards that point (center of A), and at the same time have all the particles in group A move towards center of B. POP Group A -> Center of POP Group B POP Group B -> Center of POP Group A Thanks
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