Scale is an interesting point as I've always tried to work to real world units so my particle separation is heading towards 0.005 or lower. Never tried working at a hacked scale as I've no idea which parameters need tweaking to accommodate it apart from gravity obviously. Is it a smarter move to simulate at an optimum size and scale down the end surface?

I seem to have problems when simulating anything with that has a finer thinner quality to it ending up with volume loss, or clinging to surfaces. I've uploaded a simple test to illustrate what i'm currently trying to create. A garden feature where the water bubbles out the top of a pole and flows down the outside. Simple but the water needs to be the star of the idea.

I've a very rudimentary grasp of what flip is doing… gleaned from Steve Knippings cg circuit flip series, but I've no idea how to debug flips behaviour, or go beyond the basic setups. I know for sure you don't master flips in H with the occasional sim over 12 months, but I've come from bashing stuff out quickly in Softimage and Realflow to taking a fair bit longer in H and the boss is tapping his foot!


cheers,

Andi

Looking for thoughts and opinions on this.. From the horses mouth would be amazing too.

I'm wondering if there are plans to do anything on a grander scale for liquid simulations (not really biblical floods or oceans but smaller scale stuff)? Does anyone think it needs work? I'm looking for solutions to my issue(s) with it not looking to grumble about it not working.

I have to say first up I've only been using H for 12 months so I'm a total beginner with all the problems that brings so the question comes from that perspective. Liquids or rather flip seems to be the only part of H I've not been able to get in any way comfortable with. My experience of liquids pre H is small scale uncomplicated stuff done in realflow, laterly using dyverso. I never used hybrido as the sph solver was fast enough for my needs and I could turn simple stuff out without issue. Flip in H seems like a different beast and I've really got nowhere with it. A fair few voices suggest that flip has things it's good for and things it's not and that seems to be backed up up by the kind of tutorials and masterclasses that are available.

Looking at doing some small garden water feature designs recently and after a few weeks if fidling around with flip I've felt like I should just do it in Realflow to get it done but that seems like a massive cop out and I don't have time or money to use multiple bits of software. Using the result of following a tutorial is a good start but after that I've only to breathe on a setup/parameter and it instantly turns to garbage and advice from forums seems to be unwieldingly varied.

So, more questions than my inital one… Do people who really know about it think liquids need looking at? Is a third party solution a necessary evil at this time? or Is it really just time and experience that one needs to be able to achieve quick, simple small scale liquids.

cheers,

Andi

Thanks mrCatfish,

that works perfectly, vops rather than vex and wrangles is much more familiar given my softimage history but somethings tells me i'll need to grasp vex properly at some point as i've zero coding experience whatsoever. Am I right in thinking that groups are actually just attributes under the hood?

Solver sop seems like a handy node if I just just figure out how to incorporate it properly. Here's my scenario:

I've a a long strip of points travelling along in X (like rocks on a conveyor) and each rock has a float attribute that's a random value between 0 and 1. When each point hits a certain position in X the random value gets added to every frame which is where I though the solver sop would come in. Then at a further position in X the counting stops, and a delete node gets rid of all the points who's random value is above a threshold.

I was using a group by bounding volume to determine where the counting should occur but I can't combine the counting bit inside the solver sop with the grouping bit that comes before.

How do I get the adding wrangle in the solver sop to use the group that's changing frame to frame.

Alternatively what other techniques would people use to achieve the same result?

cheers,

A>

I though it was me and I was just breaking something but I get the same behaviour with a simple test scene. I'm viewing the values in my pyro voxels using a volume slice on the import_pyrofileds node and getting some wild density or heat values. There's the normal range I would expect 0 to 1 or suchlike, and then I'm getting values like 4.10663e-26 or -3.07336e-0 which is confusing.

Are these numbers anything to worry about? Is Houdini, and for that matter redshift ignoring them?



cheers,

Andi.

Hi,

I'm using flip to show some water feature ideas, so it a couple of metres in scale. I've turned on viscosity just to stop the water moving so quickly but kept the value very low - 0.001, and turned on slip on surface and set the slip scale at .95. Once slip scale goes above about .8 i start getting little pops in the sim. I've checked for interpenetration between the emitter and the obstacle and it seems like there is plenty of space but my flip debugging skills end there sadly…

I assumed that turning viscosity on and keeping it low was appropriate as all liquids must have a viscosity value and I wanted the water to interact more with the surface rather than glide so effortlessly over it.

I've included the hiplc file in case anyone is bored and wants to take a look.


cheers,

Andi.

Thanks Michael…. Infinite ways to skin a Houdini cat, and every day learn something new.


cheers,


A.

Thanks Benny, that certainly works. To me it appears to need some convoluted thinking to have reached that solution myself but then I've only had 12 months experience at the simplest end of Houdini so my brain is still working in oldschool soft mode. Now I'm out of that hole I can crack on.

cheers,

A>

I seem to have stumbled onto what I can only assume is a Houdini weak spot. Curves. I have to draw a path for an object which starts and ends with some straight bits and has 2 spirals in the middle, so i made the two spiral parts using the curve tool and a twist sop, and made the straight bits using the curve tool and the odd transform. Now I need them to be one curve so i plug them all into a merge sop and then a fuse. The point order is screwed and the sort sop is of no use so I'm wondering if i really need to go back to softimage just to generate this curve, or am i missing something fundamental? Attached is the simple i've been using so you can see what I've been up to.


cheers,

A.

Aha, that's done the trick thank you. Embarrassingly simple….



cheers,

A>

The only display>guides that made a difference was the Node guides which just hides the terrain object itself.

One on the left is the geo where i can see where i want the curve, the right is with the drawcurve tool selected.


cheers,

A>

Is driving me nuts….. I want to DrawCurve on to a piece of geometry terrain converted from a heightfield and I need to see the geometry properly to do so. When i select the drawcurve node the terrain basically turns almost completely blue obscuring things. How do I stop it doing that? (yes I have the display node selected on the node above the drawcurve).

The other one is the edit node, It does a similar sort of thing. I'm trying to edit the curve I've drawn, and the terrain displays all the points when i select the edit node in point select mode.

Have I missed a whole section in the manual about vieport behaviour or is this really how people work?

cheers,

Andi.

Hola, newbie question…..

Simple task, drive a vehicle over a piece of terrain.

For ease of use the vehicle needs to follow a curve then stick itself to the terrain surface. Either of these things appear simple but together appears (to my beginner eyes) impossible.

My rig to stick something to a simple piece of terrain was a simple grid with 4 points, into a transform node then raycast down onto the terrain…. Use the transform node to drive around. Simple…. Now I want to use a curve to drive the position of the 4 point grid… but unsurprising to you all it's not working because of the old object level / sop level thing.

So how would you go about it?

Somehow extract the position and rotation of something constrained to the path and feed that in to grids position?

Any ideas or suggestions?


Cheers,

Andi.

cheers for that, might take a while to work my way through a massive piece of geo but at least there's a fix. Could this behavior be considered a bug do you think? It's certainly not first choice behavior so I might put a feature request or bug report in.

Hi all,

i know my noob brain is to blame here…. I'm using the creep sop to flow some points over a surface which works well, until i want to edit the base mesh with polysplit. Without polysplit the convert node to turn polymesh into nurbs surface says I have 1 nurbs surface as I would expect, but adding an edgeloop i now get 90 individual nurbs surfaces and my flowing points are understandably only flowing in the first one. I don't fully understand geometry in houdini as it's so different to other software and I imagine this is part of the problem. I've tried a shed load of convert options, nurbs nodes, remesh, sort… the list goes on but no dice.

Any clues?


Using 17.0.059 Win7


cheers,
Andi.

Uploaded a simple hip just in case…

Hi all,
just wondering if it's possible at all to set the default size, position and list order of the file browser? Every time i load a hip i have to drag the window to make it much larger and then click the date modified to list in a helpful fashion. I'm betting it's possible - like everything in H, probably with an environment variable but as more or less complete noob (in the context of H) i'm unlikely to find my way to it.


cheers,

A>

Hi RamaKrishna,

interesting set of tools.. but sadly it's the “while in the camera view” that's the crucial bit.



cheers,

Andi.

Jumping in here a bit late to the party…. I notice it will render a frame of each rop then the next frame and so on… Is this inefficient? I know if if it were softimage doing that it would definitely have an overhead.

Cheers,
A>

Any news of this RFE #92554 ?… Now i'm using houdini for real the camera is a real pain for sweeping moves. I either use the stock camera and put up with not being able to keep the camera pointed at an object, or i use a look at null and then can't use the view tools which is utterly cack handed….. I know you can control the universe with houdini but I just want a nice smooth camera move…