# All Activity

1. Past hour
2. ## Learning VEX via Animated Gifs - Bees & Bombs

Clif- 1. In my network, I create a circle and use the ends sop to get rid of the face (n-gon). The "unroll" option gives you a polyline with coincident points at the start/end. Then I copy it 4 times. This gives me 4 primitives, each of which is an open polyline. I use \$PI/2 * primnum (90 degrees) to initialize the 4 corners of the square cross-section. All the way up to the skin SOP, there are 4 polylines--each one a primitive. They just look like a single curve because of the way I've rotated the points. You can see this by doing something like @Cd=random(@primnum)... So-- there are primitives here-- and they are actually polylines. 2. Yes--but you need to be careful. In the case of a quad poly surface (poly grid, for instance)--each quad will have a vertex at each corner, but each point will be a collection of 4 verts, each belonging to a different poly (primitive). So--in a pointwrangle, which primitive number will you get with @primnum? Guessing here, but probably the lowest one. 3. modulo is super-useful! 4. Trig, vectors, linear algebra, analytic geometry and calculus are all super-useful. And Houdini/vex makes it much easier to get a handle on these things. The reason 1/@numprim doesn't work is that your numerator and denominator are both integers. I'm lazy--and rather than cast them with float(), I just type: 1.0/@numprim. The 1.0 is a float, and you will get a float. There may be a reason for not doing this, but I've never had problems with it. Hope this helps Cheers -m
3. Today
4. ## menu pan/scroll with wacom pen?

I had hopes that adoption of newer versions of Qt would resolve this issue. Wouldn't surprise me if the problem is mostly Wacom's fault. Technically, there is a way to enable MMB panning within parameter panels using Wacom's "Pan/Scroll" navigation setting. But doing so also breaks MMB navigation in 3D and network viewports altogether. The limitation would be easier to accommodate if Houdini offered more flexibility for viewport input remapping, like Blender, Modo, and almost everything else out there.
5. ## Learning VEX via Animated Gifs - Bees & Bombs

Thanks again, henderthing. It took me forever to notice that you used @primnum. For some reason I kept seeing it as @ptnum. Once I did notice it, I had no idea why there would even be primitives. I'll admit, I've used the 'ends' node before, but had never notice that it leaves behind an invisible primitive. In fact, the idea of having a primitive that exists as neither a surface nor an edge (line) threw me, too. I didn't know that was a thing. These exercises are actually the first I have ever used the modulo operator, so it also took me a bit to dissect how your 'cu' equation was working. This is much cleaner than my @k method, but certainly a lot more difficult for a beginner to grasp! After I figured those parts out, the rest fell into place and I was a little embarrassed that I had stared at it for so long, wondering what the hell was happening. LOL. What I learned: 1. You can have primitives that exist as neither surfaces nor lines. 2. There is a relationship between points and primitives. By which, I mean, a point seems to 'belong' to a primitive and you can use this to manipulate the points. Probably should have known this, but didn't. 3. More elegant usages of the modulo operator. 4. Got to brush up on some pretty basic trigonometry. Question: Why can't I do: float divp = 1/@numprim; [returns 0 instead of number expected] and instead need to do: float divp = @numprim; divp = 1/divp; I also noticed your method opened up the possibility to very easily make the number of sides procedural, too. So, I've attached that here. RainbowRing_03.hipnc
6. Yesterday
7. ## Smoke Solver | Tips and Tricks

Thanks a bunch for the detailed setup! Im genuinely curious, where does one start if they want to learn these things?
8. ## Smallest-circle problem to bound points?

I was expecting the input on the Sphere SOP to allow me to get the smallest bounding sphere of a mesh (in this case a polygon). But that's not what I'me getting the the picture below, even with Accurate Bounds turned on. So is there any known solution for this sort of problem? Here, since 2D, smallest circle problem: Scene: PRB_Bound_Sphere.hipnc Cheers
9. ## How to load in UDIM textures?

diffuse.%(UDIM)d.tif ...
10. ## Substance Painter to Principled Shader

Do any of you experience with replicating 1 to 1 the look you have in Substance Painter in Houdini 16 using the Principled Shader? The PBR metal/rough workflow with the metallic and roughness maps seems to be straight forward, but plugging in my maps from Substance Painter as is, produces a render that is much darker than what I have in Substance Painter. Perhaps the colour space is off?
11. ## How to load in UDIM textures?

Hello, I have created 3D model in zbrush and textured model in Mari but now trying to proceed to look dev process. I loaded in my model in Houdini 16 But i dont know how to load in UDIM textures. Do you know any good UDIM tutorial for Houdini 16? The ones i found seem to be out of date. https://www.fxguide.com/featured/udim-uv-mapping/
12. ## Smoke Swirls inside pyro?

Eddies/vorticies form because of the conservation of energy, lower pressure air moves so the denser air moves in to fill the vacuum, so just close the domain boundaries and move an object through it. The smoke solver does the rest.

I have this pattern for a garment and I would like it to be filled with evenly sized quads. In the image I have half of a shirt that is mirrored then I apply the divide node. So the mirror makes that dual line in the middle and the divide cuts the shape in ways that produces triangles and odd/even point matching issues. Is there another way to model this perhaps?
14. ## Stuck on cooking and HOM fundamental (Python)

Hey all, Sorry to add another Python cooking question (I've seen a lot, searching), but here goes. I have two subnets, a 'source' (from an .fbx) and a 'target'. The Objects in each correlate by name, and those in the source subnet are keyframe-animated. I'm driving the target Objects via: sourceMg = sourceNode.worldTransform() # beep boop, additional calculations go here targetNode.setWorldTransform(sourceMg) It works great, but once Houdini caches the frame the script is no longer (apparently) cooked, which makes sense--I pasted my code into a Python Script Object for convenient testing, which I suppose is not its intended use. If the HOM documentation is telling me what to do instead, however, I don't see it. There's the 'Python object' page, but I don't know that this is quite the same. In short: my script works as intended, but after the scene plays through once, Python stops moving the target nodes (I'm guessing because Houdini quits cooking it, since it's not doing anything Houdini expects it to do, like make geometry). Where does a script like this belong? I'm sure there's something embarrassingly obvious I'm missing--it's just a little extra confusing to me because I have to manipulate everything on the Object level. Thanks in advance for the help! If anything's unclear, lemme know
15. ## menu pan/scroll with wacom pen?

Yes - SESI have rejected the pan parameters panel idea for many years - it's a lost cause tbh.
16. ## Smoke Swirls inside pyro?

Here, Matt Estela has a source file and nice explanation: http://www.tokeru.com/cgwiki/index.php?title=HoudiniDops#Pyro_and_collisions Btw that superman effect is not physically correct ... those two vortices are made by two downward velocity "fields" under two wings. So you will have to fake those two fields:
17. ## menu pan/scroll with wacom pen?

Hi, MMB to pan - unfortunately no. Maybe in the future? For now I got used to this layout, you can also ladder the parameters far left/right: http://forums.odforce.net/topic/30009-h16-node-naming-coloring-and-layout-guidelines/?do=findComment&comment=168665 Btw I was many years 100% on intuos, and last month I discovered this mouse: http://forums.odforce.net/topic/31442-roccat-tyon-mouse-recommendation/ When building the network, I am happy with the mouse. Those extra buttons are handy.
18. ## Hair: "helmet hair" and scalp penetration

Two questions about hair: 1) I'm trying to get a "helmet hair" look, i.e. a hairdo that has been "pushed" closer to the scalp. I can always modify the guide curves by manipulating them as SOP curves, but I'm wondering if there's an dedicated groom (either tool or process) that would push an existing hairdo closer to the scalp. Or should I perhaps start with guide hairs that are already near-tangent to the scalp and try to create the "helmet hair" look from there? 2) While working on the problem above, I often get hair penetrating the scalp. Is there any setting in the groom tools that would force hair to always stay outside of the scalp (without doing simulations)?
19. ## Get an attribute from iteration before current from ForEach loop

That was my intention
20. ## Get an attribute from iteration before current from ForEach loop

Hello Iraklo My guess would be to use a sop solver as Folly suggested. It is really close to a for loop actually if you think about it, and you can more easily store the data you need IMHO. You can simply use a timeshift after the solver if you wish to have the result on frame 1, a for loop would also have to recook if you make changes anyway.
21. ## noob confusion about render elements

Ah found out that the mplay button had options under it if I made a hold-press, and then I could render fullres. Also figured out the workflow for multichannel exr's, with ae's builtin extraction effects, at least for doing post DOF it works fine so far. Funny though I couldnt find a reflection element AOV option ( at least not in the checkmark section ), just puzzled me since I use that all the time with vray.
22. ## Selecting points using HDA interface

Thanks, vtrvtr! That's an interesting implementation! I will give it a try and see how well it works with my workflow.
23. ## How to get unique \$WEDGE names prefix of multiple WEDGES wired

Hello rod.vfx.td, A dirty hack is to not use wedge variables but directly referencing the parameter you are wedging in the name of the file. Of course this only works if you are wedging one parameter per wedge node. Hope this can help you!
24. ## Smoke Swirls inside pyro?

Hello onkardahare, I would approach this using a velocity volume (the volume velocity node can create nice vortex effect) in SOP at the right location and add it on one frame to DOP when the collision takes places (animating the source velocity value should do the trick). A more procedural way would be to create a custom field that would be directly be linked to your collider object (move with it or being multiplied depending on the distance from it) so it would affect the rest of the sim just when needed. I hope this helps!
25. ## Smoke Swirls inside pyro?

I am trying to create a effect like when superman comes through the smoke it creates the swirls inside smoke as given in the link below, but the problem is i am not getting how to start this kind of effects in pyro. I am trying, please help me on this. Superman Saves Lois Lane _ Desert Scene - Batman v Superman Dawn of Justice (2016) Movie Clip - YouTube.mp4
26. ## Crowds: When X happens do this OR this

Nice work, glad you are getting good results.
27. ## menu pan/scroll with wacom pen?

In most other DCC apps you can mmb click and drag anywhere in a menu with a wacom pen to scroll up and down the menu, in after effects you can hold space bar to get the hand tool, etc Is there any way to get that functionality in Houdini? Its getting maddening having to click and drag on the scroll bar every time I want to scroll through a long parameter list Yes the scroll wheel on the mouse works but I use a tablet 99% of the time so that doesn't do much good. Thanks for any help
28. ## Pulse of Life

That's nuts! It looks great!
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