ikoon

If those tunnels are not animated, you could separate it into more steps: - somehow manage to keep the particles inside the tunnels, and make them reach their goal, even if their speed and behavior is not exactly what you like - generate their trails (Timeshift to the end and loong Trail) - finetune these trails in SOPs (Smooth, Resample, Point jitter ... and VDB Advect Points can also help to push them into the center of tunnels) - finally Slide points along edges, so you can art direct the speed l am curious about other approaches, this is interesting topic.

SDF is a scalar field. You could add a Volume Analysis SOP (Gradient), which will give you the "normal" direction of your SDF, and then use this normal vector to push the particles to the center of your sdf (POP Advect by Volumes) http://www.sidefx.com/docs/houdini/nodes/sop/volumeanalysis.html You could also generate Collision from your sdf, to keep your particles inside the tunnels. But I think, that those forces will be too tricky to keep the particles in the center of those "tunnels" and art-direct their speed. I would rather fake it in SOPs ... generate centerlines, smooth, multiplicate them, give them some position noise, Slide points along edges (as Matt does it here) The "generation of centerlines" issue remind me of this link: https://houdinigubbins.wordpress.com/2017/07/22/fiedler-vector-and-the-medial-axis/ Unfortunately I am not skilled enough to reproduce that "centerline" setup and source is not included there.

Please, is there any way to view the "time spent on this file (or project)"? Or have you heard about such a tool for Houdini?

The Stash SOP should help you? Quote: You can modify or overwrite the cached geometry with hou.Geometry objects through scripting. You can link the geometry parameter to a parameter on a parent asset. This allows assets to inject geometry into a network without making the contents editable. http://www.sidefx.com/docs/houdini/nodes/sop/stash.html

In vex, we cannot specify geometry as relative path. a. You may wire the MUDGUARDS into the second input, and the vex will be: point(1,"name",0) b. If you don't want to wire (or you cannot), you can add a spare input, and change vex to: point(-1,"name",0) c. Another solution, worse than b. Rewrite your vex to this: point("op:/obj/yourgeoname/MUDGUARDS","name",0) But this is probably bad, because if you rename anything in the path, vex doesn't update the code automatically, so this path gets broken. As regards spare input, it is described here: http://www.sidefx.com/docs/houdini/model/compile More is here: http://www.sidefx.com/docs/houdini/io/op_syntax.html

Hi Marian, EDIT: sorry for the previous code, this one is better: $HIP/render/${HIPNAME}_`opname(chs("RS_renderCamera"))`_$F4.exr Those curly brackets are needed, because without them $ searches for the variable HIPNAME_ ... because _ can be included in the variable name.

Hi Pancho! I am glad that I helped. I like the Houdini Animation Editor a lot, there are many "hidden" features to all those handles ... which made me confused at first. But they are useful. To make my answer more complete, for bezier keyframe, you may also select (or drag) the tip of the bezier handle or the "line" of the bezier handle. Then, for example, with Ctrl pressed, each of these partial handles give you different behaviour. Good luck with your work!

Hi Tom, as regards the greying out. I am not sure if I understand right. The "keyframe" can be selected as time, when you click on the vertical handle: as a value, when you click on the rhombus : or as both value and time, when you select both (most often by dragging a marque): I have this setting, because I don't like nonselected handles visible: As regards the scaling. You can enable "box handle" for selected keyframes and pivot here with these icons, default hotkeys are Y and Shift-Y

Btw maybe the "overwhelming" feeling is good for us, as our brain needs to embrace the complexity. I am no guru, but smart ideas and good solutions in Houdini come from utilizing the complexity. Sometimes using CHOPs is the simpliest solution, sometimes vex, python. Sometimes smart SOPs before sending the geometry to DOPs. Sometimes SOP solver inside DOPs. Houdini is complex, but it becomes joy.

Hi Abhigyan, welcome! I think that the "overwhelming" feeling is inevitable at the beginning. Or ... I don't know a way how to avoid it, I was there also (and I am, often, still). I wish you the best luck. Sepu mentioned very good resources. Here was similar talk, so maybe some more tips: https://forums.odforce.net/topic/30359-tips-suggestions-and-strategies-for-learning-houdini/

Hi Antoine. Try to compare your settings to these I post below. And also, after you Apply the settings ... create new Scene View, to be sure, that you are trying the new settings:

It is possible to pick colors outside of Houdini, MMB and drag the colour "preview rectangle" https://houdinitricks.com/sample-colors-outside-of-houdini/

Petr this looks amazing!!! You did exactly what I wanted! We should have "donate" button here, not just emoticons I will dig into it. I want to use it in cases, when I build an effect in sops (motion design, videomapping to music), when I branch the SOPs a lot. For example I animate geo, I use it for sourcing particles. I also convert the geo to VDB, and morph it slowly to another shape. Calculate velocity field, swirling around the morphing shape. Then volume vop the velocity field to music... etc. and I still emit particles on each music beat from the initial animated geo. I have filecaches along those branches, to be able to preview and iterate. But if I have to update some "far" upstream parameter ... then I get lost what filecache should I recompute. You really REALLY help me to save a lot of time and nerves I will PM you!

Ben, thank you very much!!! I also plan to use .sim checkpoints for additional animating of forces, or amounts of dissipation, sourcing... Lets say I have simulated 300 frames. Until frame 150 the sim looks fine. Then the particles should stick more to the moving geometry ... but they fly away, so I will animate the attraction force, and slowly increase drag, from frames 160 to 200. Maybe it is not the right attitude, to patch the simulations like this. I am DOP beginner, I do quite simple motion design and learn, so far. Technically it should be fine, as long as I only animate the channels?

I got an answer from SideFX (twod) so I just repost it here: You can't use it directly. Packed Alembic and Packed Disk Primitives/Sequences can cache geometry there, and all currently displayed geometry will use the cache until it's deleted. But there's no way to manually cache things. With HScript we may set the memory limits: http://www.sidefx.com/docs/houdini/commands/glcache.html