jamesearnest244

Interesting, I'll give this a whirl on the weekend. Still I'm pretty sure there's a way to get around this issue with FLIP. I wonder...

-Reply created by mistake-

Hi, I'd like to ask if anyone has a methodology they can share for approaching small scale FLIP simulations. We all know FLIP has stability issues when working in the real-world scale of coffee cups and cereal bowls. But I haven't found any info that addresses directly how to get around that. If you scale the scene up by, say, 10, to get to units Houdini is more comfortable with, do you then need to: scale up gravity? Scale up collision velocity? Scale up Time Scale? I've read about the Spatial Scale setting in the Solver tab, but when I go by the documentation and set it to 0.01 (for a scene modeled in centimeters), I can't get even one frame simmed. IMHO since it's an exact scale of units, there must be a simple mathematical way to accomplish this in a couple of settings to get things to match up. Or am I wrong and it's going to take endless tweaking just to get things looking sorta right? I'd appreciate any input!

I finally figured it out! I had to write icmax(0, $C) in the expression CHOP. When writing icmax(0,0) it was using the 0th channel's data and applying it to all the channels, instead of evaluating per channel. So writing $C in an expression CHOP is kind of like writing @ptnum in point wrangles. I'm attaching the file in case anyone else runs into this in the future. Thanks @Librarian for sticking around! Chops_MaxValue_Solution.hipnc

I added the simplest use case I can think of to the last file you attached - deleting all points that exceed a certain speed at any time. But I don't want to delete them only when they reach that speed - if they are going to exceed it at any point in the future, then delete them right from the beginning (that way the point count remains consistent). The last file you attached does assign consistent values to the points, but they're not the actual speed values. I'm not sure what they are. So the wrangle I put in doesn't do what it's supposed to. CHOPS_UseCase.hipnc

But now all the points have the same value, that can't be right. I think the Combine Channels operation on the Math node makes it take the maximum value any of the points reaches, and applies that value to all of them. Look here at the info on the Geometry node - these are the values I want to extract per-point. Is there a way to turn these values into attributes on the points themselves? So, for point 0, @max_speed = 2.1371527. For point 1, @max_speed = 2.371021, etc... I'm trying all sorts of approaches and can't get it to work. I found the function chinputlimits in the documentation, maybe that's the key? I'm just so inexperienced in CHOPS I don't seem to be using this function correctly in my attempts.

I really appreciate your help, it's just still not quite what I'm after (I hope I'm not asking too much). The speed attribute here is still changing per frame. I'll try to be as clear as I can: Let's assume that point X has @speed=1 in the beginning of the animation, @speed=5 in the middle, and @speed=3 in the last frame. I want to generate the attribute @max_speed=5. This value would be different per point, but would be constant throughout the animation, because every point has a definite maximum speed that it reaches. There are actually many situations where I find this info would be useful. Any time I'm modifying values with ramps, clamps and the like in VOPS and need some precision, rather than eyeballing it by plugging into the Cd output.

Thanks for your help with the file! But the values here are still changing every frame, so it's not quite what I'm after. If I understand this correctly, what this setup seems to be doing is mapping the current speed of the points on the current frame to a range of 0 to 1, with respect to the maximum speed attained at any time. What I need is every point's actual maximum speed value, not a 0-1 mapping of it. Do you maybe have another idea how to get this data?

I do get values, but they change every frame, so clearly they're not the values I'm looking for. I need to get the maximum value the attribute reaches at any time over the course of the animation.

Hi, I know this is a super old thread, but I'm trying to accomplish the same thing with no luck. I attached a simple example file. I'm trying to have CHOPS overwrite the speed attribute with the maximum speed that each point reaches over the course of the animation. Ultimately, I'd like to know the maximum value any of the points reaches. I'd appreciate if anyone could point me to what I'm doing wrong. Thanks! chop_help.hipnc

Thanks ikoon for the quick answer!

Hi, I'm sure this is straightforward, but for some reason I'm having trouble assigning a hotkey within a specific pane. For example, I would like Alt+L to activate the Edge Loop shelf tool, but only when my cursor is hovering on the Scene View pane. If I Ctrl+Alt+Shift click the tool on the shelf, it brings up the Hotkey Editor with this tool selected and ready to assign a hotkey to, but I can't find any option to define the pane within which this hotkey should work. It only lets me define a global hotkey that isn't pane-specific. I'm sure there's to do this though, because all hotkeys in Houdini are pane-specific, and this is even evident in the Hotkey Editor itself. Any tips? Thanks!

Hi, Is there a way I could set a shortcut in the MAT context that would connect the currently selected node into the network's surface output? When testing out different noises, images etc. I find myself constantly doing this to see how the texture maps onto the object, and a hotkey would be really handy. Thanks for any tips!

Alright, I used the Wire Deform method and it worked. Thanks a lot for the help! I wonder why the numbers go crazy though. I guess it's just best to avoid re-generating geometry as part of the node network if it can be avoided.

Hi everyone, In this file I built a basic setup of a deforming tube, and for some reason the ptnum value keeps changing abruptly mid-animation. The topology and number of points doesn't change, and I just can't figure out what is causing this. The problem happens at frames 51>52, and then again at 114>115, 177>178, and probably again afterwards. I tried lots of different things and nothing worked. I'd appreciate any help! ptnum_problem.hip