# All Activity

1. Past hour
2. ## sort by attribute ?

Hi I'm trying to resample several primitive groups differently. (Marked in red in the picture) the curve comes from an alembic files. The problem is that split then merge seem to break the skin sop. I guess, as you can see on the picture, it's because after the split there is a hole in the prim numbering. That's why I put a Sort sop by a attribute but I can get it to work. (the @pid attribute is ok) I think I'll just lengthen the shortest curves, so I won't have to split the curves, but I'd like to know why this set-up fails. Some ideas ? Coque resample.hipnc
3. ## learning Getting Objects to spawn on the Normal location

This works great for positioning the points, but it won't actually inherit attributes like N from the primitives' points... that's why Attribute Interpolate might be a better way to go, since it'll automatically interpolate vector attributes from the original points that make up each primitive.
4. ## learning Getting Objects to spawn on the Normal location

you can also... cause I do this alot: Use this in a primwrangle: ///Add Center Point addpoint(0, @P); ///Remove Prim removeprim(0, @primnum, 1);
5. Today
6. ## learning Getting Objects to spawn on the Normal location

Primitive normals don't actually exist... they're the normalized average of all associated point or vertex normals that comprise the primitive, drawn from the primitive's barycenter. If you want to create points at those locations, one way to do it with minimal scripting is to facet your polygons to unique the points, then compute point normals, then use a Primitive SOP to scale down the primitives to 0 so they each become a single point (make sure that you remove N from "Vector Attributes to Transform"), then Fuse the points to average the normals. If you're okay with scripting, you could also use addpoint(0, @primnum); in a Primitive Wrangle to a point for each primitive. Then set i@sourceprim on each new point to be the primitive number, and v@sourceprimuv to be (0.5, 0.5, 0.5), which for any quad will be the barycenter of the primitive. Then use Attribute Interpolate to compute the normal for each of these new points.
7. ## Toms "Learning Houdini" Gallery

Some screenshots from the above Circuits R&D: Houdini 17.5 Cheers, Tom
8. ## Use color information to deform a geometry ??? [attribfromvolume] > [peak]

fantastic!! It works! I understand better how the expression functions ... I will be able to advance on my learning. thank you very much Drughi !!!
9. ## Retime simulation

I know retime node has improved in Houdini 17.5. I think you can simulate normally (i.e. realtime scale) then use retime node to speed up or slow down (you might need more substeps to help retime if it needs more data for slow part)
10. ## Toms "Learning Houdini" Gallery

"Octahedral Lines" Combining above with some more VEX and some connect adjacent points/smoothing: Houdini, Redshift, Luminar 2018 Cheers, Tom
11. ## Exporting Transforms to Alembic

I just read the documentation of Guerilla. It seems their instancing system uses a base mesh (called a « scalp ») on which they scatter / instance objects (couldn’t understand if it is instanced on the points of the mesh or randomly across the surface). Guide curves (usually a kind of polyline) are used to determine orientation of instances. it is really similar to what’s happening in any grooming system under the hood. That’s why I suggested using grooming tools, but I haven’t got further in my réflexion unfortunately :-) That being said, it seems that they accept point cache files of particles. But I don’t know how to generate that from Houdini.
12. ## Toms "Learning Houdini" Gallery

"Spiraling Lines" Followed the tutorial by ROMAN PILLAI https://www.sidefx.com/tutorials/spiral-pattern-generation-tutorial-houdini-cinema4d/ Then implemented it in VEX. Houdini, Redshift, Luminar 2018 Cheers, Tom
13. ## pscale flickering due to changing id

point count is always changing, hence using @ptnum for any randomization will always give new result on each frame...try to find an invariant that will always be the same (I know this has not answered your question , sorry ) . I've tried using origpt instead, did not look right though, but I think it should be used as a starting point. Also, another idea (which is slow and inefficient) is to use to use the last frame of the animation where you have the full tree and assign pscale based on origpt and use transfer attributes to transfer pscale to the dynamic points (but again, I am sure it's easier to use origpt in the first place...)
14. ## Toms "Learning Houdini" Gallery

"Organic Circuit" Houdini, Redshift, Luminar 2018 Cheers, Tom
15. ## Toms "Learning Houdini" Gallery

"Her Aura" And so she stood Breathing Feeling the space around her Letting her aura expand Touching the trees, the flowers, the bees Inhaling the fragrances Healing deeply Houdini, Redshift... Cheers, Tom
16. ## Exporting Transforms to Alembic

@Thomas: thanks for input, will investigate "AlembicRef" as I never heard about it before! @Jo: sorry, I totally lost you here, can you elaborate more, I did not get what curves has to do with the orientation? and how it's related to a mesh?
17. ## Exporting Transforms to Alembic

That being said, Guerilla instances based on meshes and guide curves for orientation. Maybe you can use the grooming tools and export these guides as well as the « scalp » in an Alembic. Depending on what you need to instance, this can work...

Particles and instancing of animated ribbons. or a cloth sim with lots of very low rez ribbons and smoothing / point deforming (probably possible to use Vellum). I did that once for a bunch of paper sheets coming out of a building.

please watch this video : https://vimeo.com/172598946
20. ## 17.5 - Vdb To Spheres - Different than before?

Weird, so it's working correctly on 17.5.350 but not on the latest? Hm.
21. ## pscale flickering due to changing id

Hi all, I am currently having this issue of pscale flickering due to changing id every frame, is there a way to predetermine the id before the playback, so that the id will always be the same? pscaleID.mp4 pscaleID_v001.hip
22. ## learning Getting Objects to spawn on the Normal location

Impossible to know what happens inside your delete-node and vop-node. And since its all merged, the screen doesnt realy help either.
23. ## box stacking no interpenetration

wow thanks! wouldn't have thought of frame by frame stacking. Also not how to do that much in VEX. Thanks. This give me something new to play with
24. ## Retime simulation

What is the best way to retime and control the speed of a simulation? My desired effect is high speed and upon collision slowing down like 100 times for 5 seconds and then go back to the original speed. retime.hiplc
25. ## 17.5 - Vdb To Spheres - Different than before?

Here is 17.5.350 Seems to be working correctly
26. ## 17.5 - Vdb To Spheres - Different than before?

As I have my old version always installed I test it. The most notable difference is on the large spheres. As on the old version the parameters are always activated I set it to have the same result as yours. Top to bottom H15, H16, H17 or 175
27. ## Can I use default interpreter with hou?

Hello, My Python experience is rather limited here, so I know my question might be so basic! I am running Houdini 17.5 on Ubuntu. I need to write some tools for Houdini, so my first assumption is that I can just run the default python2 interpreter and import hou, however when I do that python interpreter crashs (first complains about jemalloc library then crashs). So my second guess is to run the python interrupter that comes with Houdini and then import hou, this time, it does crash but still complains about jemalloc library? Now, I go directly and run hython and import hou and things seem to work nicely (i.e. no crash, no complaining about jemalloc). My questions: 1-I, i.e. the company I work for , have a production environment that already uses the default python, how other TDs integrate hou in a company pipeline without requesting to change the interpreter to hython? 2-Why SideFx ships it's version of the python interpreter? is it special? is it different than the default python interpreter? OR is it just to eliminate any external dependencies? As I mentioned above, when I used the shipped python and imported hou, I got still jemalloc warning too! Thanks
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