Fluvio - Fluid Dynamics for Unity

Here's a pretty cool tip for anyone making a game with pixel art. The fluid effect supports both point filtering and downsampling, which makes it easy to make 8/16-bit fluid dynamics:

 

The next beta will introduce a default option for gas particles:



This is already pretty easy to do, but its a request I get often, so I'll add it as a default. The above image can be reproduced in the Free Edition in its entirety (that's only up to 1000 particles there).

In the future I plan on making some gas-specific shaders with some self shadowing, blurring, and such.

Also, I've added back simulation scale from Fluvio 2. As an added bonus, in the editor you can scale all particle systems in a fluid group as well.

 

Added turbulence forces to the fluid solver:



To explain what's going on here - Both fluids are identical. The one on the right has a higher turbulence probability, and an effector at its base (not shown) that applies an amount and direction of vorticity to the particles within it. The effector also gives each particle that crosses it a chance to become a "turbulent" particle.

Turbulent particles will twist around other particles, transferring their vorticity and turbulence probability to other non-turbulent particles. Eventually the turbulence probability will become diffuse throughout all of the particles and the turbulence wave will stop propagating.

The turbulence is very artist controlled, as the effectors determine both the strength and direction of vorticity.

This property works for both liquids and gasses.

 

Are you sure you uploaded the fluvio update correctly ? In the lattest update the shaders are pink and complaining about implicit truncation under directx 11 . The water shader in your first beta worked perfectly for me. Any ideas ?

 

Hey Ian,

What version of Unity are you using? If you're on 5, you need RC2 or higher, due to some changes with Unity's standard shader (also try redownloading beta 2 as I had to upload it twice to fix that issue).

 

I tried redownloading the latest Unity 5 version and importing the package into a new project but still have the same issue. all fluvio shaders don't appear to be compiling properly as they are all pink. I also tried importing shader forge to see if it was a unity error but shader forges shaders appear to compile correctly. I have installed the 32 bit version of unity for windows as I need to use some 32 bit editor packages. Anyone else having an issue or does my computer just hate me ?

I would also suggest that you recreate the fluvio 2 waterfall demo with fluvio 3. If people purchase fluvio they will be confused as to why they don't have the waterfall scene shown in your demo videos.. I would suggest that you make a waterfall demo as well as a demo where you throw a rock into a river and it creates a splash where the rock hits. I think in reality the most likely uses for fluvio are going to be for watersplashes, waterfalls and perhaps smoke from a chimney. I would also suggest making a demo where you fill a container with water and have a turbine in the water to make waves in the water.

Also out of interest how accurate is fluvio at high pressure steam. Would it be able to simulate a steam train for example ?

 

Hm, beta 3 will go up later today (EDIT: holding off on beta 3 for a little bit while I work on bug fixes) and should hopefully fix things. I'll take a look to see if the last build ended up breaking stuff. Meanwhile, can you open a support request at https://support.thinksquirrel.com with your Editor.log file so I can double check on the shader issue?

Still lots of work to do with updating the current demo and promotional materials - the waterfall likely won't come back in the same form - it was a few hundred megabytes!

We want to move away from sticking a bunch of demo scenes into the package itself and provide separate demo packages (similar to how Unity provides one example project, with all other examples available free on the Asset Store). That's a bit further out on the roadmap, but it's happening

High pressures aren't a problem, but you may have issues simulating something like steam or internal combustion engines. While pressure is a fluid property for SPH, temperature is assumed to be fixed/diffused across the fluid volume (gas constant + ideal gas law), and for engines like that its important to also model how differences in temperature affect pressure.

As far as steam effects or general dynamics/visualization of high pressure steam, no problem there

 

As part of the turbulence changes coming in beta 3, effectors are getting some extra properties:



Effector forces can now be radial (as before), or directional. A new property, vorticity, controls how much turbulent force is applied by the effector. Without any effectors, a fluid is considered non-turbulent - effectors induce turbulence among particles.

Also, the falloff strength of both effector forces and effector vorticity can now be fully customized as an animation curve. This curve can also be animated as well, to produce very complex external forces.

Just a reminder as well that effectors are now available in the Free Edition - I highly recommend trying them out

 

Hi I just tried using fluvio with the lattest release candidate 3 but still am having the issue with the shaders being pink. I've attached a screenshot of the errors in the unity console.

 

This has already been fixed, as per the post above (just verified with the packages on the Asset Store). You'll have to redownload the packages manually - you can do this by going to the download manager and clicking "update", even if it says the package is up to date.

 

A recap on beta 3 - hope to have this out by the end of the week, it was delayed last week due to some breaking issues.

This release has some new features, as well as bug fixes:

• Turbulence/vorticity - see posts above for more details on how that will work
• Simulation scale and particle system scaling (particle system scaling is in the editor only, simulation scale can be changed at runtime)
• Matrix multiplication can now be done on the GPU. This gets rid of much of the overhead of large particle counts by doing world space/local space matrix multiplication, physics integration, and 2D constraints on the GPU (on the CPU side it's just a copy from Fluvio to Shuriken). This fast path is only accessible if all plugins are also hardware accelerated.
• Color by density/Size by density plugins - fairly self explanatory, they work similarly to Shuriken's Color by X/Size by X curves and gradients.
• "Infinitely" sized simulation area. Currently, spatial partitioning limited fluids to 64 grid cells in each dimension (64 * smoothing distance) - particles outside of that range stopped simulating. That grid now extends infinitely in every direction. Of course there are still limits, but they're past any reasonable particle numbers.

Other updates include:

• Full API documentation (component reference and an update to the support site is coming soon)
• Various general bug fixes
• Intel's OpenCL driver should work now
• iOS support (C# solver only, includes support for IL2CPP and code stripping up to micro mscorlib)
• Windows Phone/Windows Store support (including support Unity's native compute shaders if available) NOTE: Windows Store/Windows Phone won't support the multithreaded solver initially, but support for that will come in a future beta.

 

does this new version support build for windows phone 8 platform?

 

does the free version of Fluvio 3 support build for windows phone 8 platform?
or how to deploy project with this version of fluvio in windows phone?

i cant build to wp8 in the past fluvio version

 

It will as of beta 3, yes.

EDIT: I've updated the post above with details on iOS and Windows Phone 8/Windows Store support.

 

And beta 3 has been released

A short note to anyone using betas 1 or 2: A bugfix went in that fixes an issue where particles would ignore forces for the first frame. This may make your particles spray too much - to fix it, you may need to increase the size of your emitter shapes slightly.

 

What a wonderful package you got here Thinksquirrel,
I stumbled upon it while looking for a way to efficiently make dynamic fluid decals within Unity.
To my amazement Fluvio supersedes that idea by miles! It's this demo in particular that caught my attention

I can only imagine the addition of PhysX 3.x integration on Unity 5 is going to make this asset stand out even more.
I can't wait to get my hands on it :O As soon as I get back to my project I'll be purchasing Fluvio 3.
Should be around this Easter if all goes well, fingers crossed.

Great job Thinksquirrel, tip of the hat to yous

 

Thanks! The biggest thing Unity 5 brings to the table is the new fluid effect, with self-shadowing and PBR - it's quite a step up from the older effect!

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On an unrelated note - I've just uploaded a Getting Started video for Fluvio 3:

This video actually plays in the editor (without audio) in the new Welcome Window, which is coming in beta 4:


This particular video is geared for customers to quickly grasp the basics of the interface, but I plan on having some showcase videos as well as more advanced topics and learning content in the future.

Let me know what you guys think, and if you'd want more of this kind of content.

 

Is it possible to upgrade to Fluvio 3 standard from Fluvio 2.x standard without losing any custom fluid prefabs we have made? Having trouble with missing script references on 2.x prefabs after upgrading to Fluvio 3

 

Unfortunately Fluvio 3 isn't backwards compatible with Fluvio 2.x There were a lot of sweeping changes (components combined into other ones, unmaintained code removed, a rewrite of many of the solvers), so it will require a manual upgrade.

Fortunately, the codebase is much more rock solid, so sweeping changes like that won't need to happen again.

If you're running into any specific trouble with performing a manual upgrade, feel free to open a ticket and I can offer some tips and help directly.

 

:-( bummer, I guess I need to remake my prefabs.

Question: I was using fluvio for blood effects. I was wondering if it would be possible to make the viscosity variable affect something like, if a fluid were to splatter onto a wall, how slow it would trickle down the surface. Is this currently possible, or perhaps in the future?

Also I was looking at the best way to have the fluids create pools. I was messing around in 2.x with using the collision event to spawn a particle that looks like a pool, but ran into the trouble of it being created whenever it hit a wall as well.

Any tips on how to best replicate that feeling of gory mess, ala Evil Within?

 

The effect you're describing is actually surface tension between the fluid and the wall, not viscosity. I highly recommend checking out the new paint example - it uses an effector along the surface of the sphere to pull particles toward it. That should work well enough in pretty much any case. Objects you want blood to stick to can just have effectors on them.

As for pools, they should form naturally (again, the paint example would be good to look at for this). If you want to say, replace a group of particles with some object (maybe for performance reasons), I would look into either using Shuriken collision events + physics layers (outside of Fluvio), or maybe a custom plugin that replaces particles once a certain amount are in a specific area.

 

Fluid-rigidbody interaction!

This with beta 4, probably as the only new feature so that I can focus on bug fixes. It's always been fairly easy to do with a simple script, but I'd like to make the process even simpler for artists and other non-programmers.

Interaction will be enabled by default, and can be enabled/disabled by just enabling/disabling collision messages and changing a force modifier.

Here's a scene I set up in about 5 minutes to demo this:


As a bonus, here's some performance numbers on that scene (using GPU acceleration with OpenCL):


Note that this feature uses Shuriken collision events, so no 2D collider support. Right now I recommend having a separate 3D collider for fluids if you're working with 2D. Send Unity some feedback asking for 2D support for the particle system!

 

Is there anything I need to do to get the GPU accelerated fluid working?

I just checked the Paint example and the performance is pretty bad, 143 ms using the C# solver. Any other options for solver in the Fluvio settings are greyed out.

Any requirements for this? I have a Radeon 7800 series video card running on windows

 

GPU accelerated fluids require Fluvio Professional, since they currently require the compute shader solver's source code in the project.

 

Hmm that's another bummer. So what's the point of including the C# solver? I mean 140 ms is very far from game ready and it gave me a not great impression of the package, in fact, I thought it was broken. That's the only 3d demo scene now included and by default, on what I thought was the full featured edition (I bought standard since I didn't need source code access for htis plugin, since initially it was sold as having feature parity with pro) .

What does the solver do exactly? Having it on meant the scene was a slideshow, with the standard version.

Anyways if there is some sort of feature disparity between Standard and Pro versions now I kind of wish it had been more readily advertised. As a paying customer it feels like I've had the rug pulled from under me a bit. My purchasing decisions would have certainly been different had I known there would be feature disparity between standard and pro aside from source code access. I do see now that the table on the website shows the difference but I purchased Fluvio before version 3.

 

Well if you bought it at full price then he said he offered an upgrade route?

 

I think there is actually a bug or something I don't understand about fluvio performance in that paint demo. It says it only has 5000 or so particles but runs slower than other examples with more than 50000 particles. Is fluvio affected more by particle density and collisions than it is by particle count or something ? Why do smoke demos seem to run more efficiently than that paint demo for example ?

Even the cpu solver in fluvio 3 is more than twice as efficent as fluvio 2 I just think the demos you are including aren't very good at demonstrating it. Your waterfall demo in fluvio 2 was far more efficient with its usage of the solver. You need to make demos more geared to work on the cpu solver especially as someone will probably look at fluvio free before making a purchase so you want a demo that works well on that as well.

 

Thanks everyone for the feedback.

I definitely hear you with this. I don't think it's an ideal situation, but I should stress that the limitation is for technical reasons. I'm exploring avenues to get a native solver for all Fluvio versions, as well as other platforms that allow it besides the editor and standalones. I'm not sure when this will be released, but it's a priority.

As for why the C# solver is so much slower, unfortunately a lot of that is unavoidable. The code between the solvers are identical - there's just a lot more managed overhead for tasks like this (slower indexing into arrays, bounds checking, etc).

This is true. I'm going to go ahead and extend that offer to those who bought Fluvio Standard in the recent sale, too. I'll make a post below with specific details on that.

Rendering takes quite a decent amount of GPU performance. The paint demo uses the fluid effect, where smoke/gas use the default particle shader, which is much cheaper. Some of this still needs to be optimized throughout the beta, but some of this is to be expected. I'll be taking a pass at the renderer with the goals of being able to have it run much better on mobile (which also will help with optimizations on all platforms).

Other things that affect performance that you might be seeing:

• Running in the editor has additional overhead, a bit more outside of play mode. I don't optimize static fluids outside of play mode so that they can be moved around. The inspector also has a small amount of overhead. This is due to reflection wizardry with Unity's internal APIs in order to edit particle system curves, display Fluvio as modules, etc. I have some plans for this (dynamic emission of an assembly so that I can link to these APIs more directly), but that's out of scope for the 3.0 beta.
• Active particle count, collisions, and density/filling volumes all affect performance.
• The fluid mixer (in the "3" example scene) is a fairly expensive effect as it runs on all particle pairs.
• For the fluid effect, screen size will affect render performance (the effect is GPU bound).

The end goal is to have a native solver path for *all* versions of Fluvio (including free) with C# only as a fallback, and eliminate the performance discrepancy between editions.

 

Regarding upgrades:

We can do upgrades from Fluvio Standard to Fluvio Professional. For more information on the process and to see if you qualify, contact us directly here.

We normally do not provide upgrades for assets purchased during sales - however, if you purchased Fluvio Standard on 12/25/2014, you may be eligible to purchase an upgrade.

 

Ooh that does sound tempting, have to see if I get my Pro refund approved!

 

So I've explored some options technically and made the following decision:

OpenCL hardware acceleration will be available in both Fluvio Standard and Free, including the compute shader API for making plugins. We don't want to limit projects based on the speed of the solver by any means, and have come up with a way to do so. The source for the compute shader solver won't be available (it'll be just an auto-generated, intermediary code blob) - OpenCL will still be able to compile and run it though. Free Edition's particle limits will still extend to compute shader buffer sizes.

Unity's native compute shader support (DX11/consoles) will remain a Fluvio Professional-only feature. If you're targeting Windows that shouldn't be a problem though - OpenCL tends to be faster than DirectCompute in many cases.

 

That is very cool and will make the transition to Pro or standard later much easier. Very nice direction

 

Fluvio 3 beta 4 is out! Beta 4 adds hardware acceleration to Fluvio Free Edition and Fluvio Standard, built-in rigidbody interaction, a new welcome screen with a getting started video, and various bug fixes.

 

Hi I'm getting the OpenCL build crash mentioned in the beta notes, what version of Unity should the example scene run on (so I can check if should run OK on what I have) and what information do you need on the crash, Unity log, graphics card and driver info?
Thanks

 

Hi overthere,

There are a few things you'll want to try if you get an OpenCL crash:

1) Reimport the compute shader folder under Fluvio > Resources > ComputeShaders
2) Try going into and out of playmode. This works for me in 90% of cases
3) If you have an NVIDIA card, you may be running into driver issues (their OpenCL support is pretty bad, unfortunately) - I recommend using the GPU driver from their CUDA toolkit (https://developer.nvidia.com/cuda-toolkit)
4) Finally, you may have better luck with OpenCL on the CPU (it's still much faster than the C# solver) - you can get OpenCL drivers from Intel and AMD here if needed:

Intel:
https://software.intel.com/en-us/articles/opencl-drivers

AMD (AMD's drivers will work for AMD cards, Intel CPUs, and AMD CPUs):
http://support.amd.com/en-us/kb-articles/Pages/OpenCL2-Driver.aspx

Finally, if you get a bunch of driver crashes, the following script on Windows (as a .bat file) will restart your graphics driver. Make sure to replace "NVIDIA GeForce GTX 770" with your device name. Also make sure to exit Unity first or it will crash:

Code (csharp):

1.  
2. @echo off
3. echo.
4. echo *** Restarting GPU
5. timeout /t 2 /nobreak >nul
6. devmanview.exe /disable_enable "NVIDIA GeForce GTX 770"
7. echo.
8. echo *** Restart finished
9. timeout /t 2 /nobreak >nul
10. taskkill /f /IM explorer.exe
11. explorer.exe
12.  

-------------

I'm currently looking into the NVIDIA related issues mainly right now - I may end up maintaining a separate version of the solver that uses CUDA for NVIDIA cards, but I don't want to have to go down that route

Feel free to send the following info through a ticket at support.thinksquirrel.com:

• Editor or player log with the crash
• A screenshot of your OpenCL information if that is working (under Edit > Project Settings > Fluvio). It won't be visible after a crash, so take the screenshot before the crash occurs if possible.

 

I've submitted a hotfix (should be up today or tomorrow) for some AMD cards, thanks to a bug report from @overthere. This one can be manually fixed though, and I've included the instructions below:

1) Open the following file:
Assets/Fluvio/Resources/ComputeShaders/Solvers/SPHSimulationSolver/OpenCLShader.cl.txt

2) Remove the following line:
#pragma OPENCL SELECT_ROUNDING_MODE rte

3) If Unity doesn't reimport automatically, reimport the ComputeShaders folder.

If you don't see that pragma statement, then you've downloaded the hotfixed version and should be fine.

EDIT: That was quick! The hotfix (still 3.0.0b4) should now be live.

 

For some reason when you first import fluvio and press play on the demo scene the performance of fluvio is really slow. If you highlight the object in the editor with the fluid attached it starts running properly. Also on your paint demo the demo runs much faster if you disable and then reenable the fluid before pressing play. It might be worth looking into why this is the case as most people will just import fluvio and press play on the demo to see how good its performance is and be confused as to why it runs so slowly.

 

Yea, these are known issues with the beta right now (related to issues with how fluids are being updated in edit mode). I'll be working through fixing these for the next beta though.

 

Hi, am trying to use Fluvio 3 pro in Unity 5 to make a waterfall like the one in the old demo. What do i need to do to make something that looks like water? How do i make it flow down a terrain ? How do i (and should i) make a river that flows across a terrain. There are only 2 demo's and nothing there seems to help with what I am looking to do. Thanks in advance.

 

Hi Adam,

The Unity 4 example used the Additive Lit fluid shader (without the fluid effect) with an animated foam texture. To make it flow down a terrain, you will want to enable the collision module in Shuriken, as with other particle systems. Default settings were used for the fluid's physical properties.

You could make a river in the same way, though I tend to recommend combining meshes and particles for large bodies of water (it depends mainly on the scale of your application). The waterfall in the old demo did this - The waterfall was simulated, and the body of water below it used Unity's standard water.

I will be re-releasing a Fluvio 3 version of this scene soon as a separate, free asset on the Asset Store.

 

Thanks for your prompt response, I now have particles flowing down a hill
Next question is can you please do a screen shot where the settings make it look more like water?

 

I've attached the water texture used in the waterfall demo here. Just create a material with that, and turn on UV animation (4 rows, 4 columns) and stretched particles for your particle system. I don't have the exact settings around right now but that should do it.

 

An additional note on the future of the example scenes, as I haven't really covered this yet.

In one of the next few builds, I will be splitting off all Fluvio examples into their own Asset Store packages. This will help ensure that these examples will always persist throughout updates and version changes, and also cut down fairly significantly on file size (and increase how often I can push updates).

The currently planned examples are:

Fluvio Examples: Paint
Fluvio Examples: Three
Fluvio Examples: Waterfall

The goal is to be able to expand upon these examples a bit more as well, by including extra scripts that won't be a part of Fluvio core, but something that can be looked through when learning how to use the product.

All of these examples will be free and compatible with all Fluvio editions.

 

Thanks for the texture - wasn't quiet sure what to do with it - never tried to make a water asset before.

Also, out of curiosity, my frame rate went from about 100fps to about 45 when I put fluvio in there. It's running on a pretty solid windows desktop with a decent nvidia video card.

If you could upgrade the waterfall demo for latest version of your asset and u5 sooner rather than later that would be very much appreciated.

 

You may want to try OpenCL CPU simulation instead of GPU simulation with OpenCL or DX11 - depending on your GPU bandwidth or other things going on in the scene, the CPU simulation may be faster (both are faster than C# simulation). Of course, collision has an additional performance cost as well (more so if collision messages are enabled). You can get more exact numbers for tweaking performance using the Fluid Debug plugin.

I don't have a date for this yet but it's fairly high on the priority list.

 

Hello Thinksquirell,

I downloaded the last version of Fluvio free and I am using Unity 5. Shortly (few seconds) after putting the liquid fluid particle system, into the scene, my driver crashes^^', something like windows kernel display, I updated my graphic drivers and I am using a gtx 650M.

 

Hi Minsc,

This is a known issue with the current beta, especially with NVIDIA cards. I recommend checking the following post for details and possible fixes:

https://support.thinksquirrel.com/hc/en-us/articles/204045684-Fluvio-3-beta-known-issues

For the next beta, I am actually going to make OpenCL CPU the default compute backend (along with a link to our recommended OpenCL driver), while I work through the GPU specific issues.

 

Any plan to fix this ?


Running on Unity 5.0.0p3

 

Hi HGarry,

To use the source code of Fluvio Professional directly, you'll need to follow the guide here:
https://support.thinksquirrel.com/hc/en-us/articles/202481980-Fluvio-Professional-source-code-guide

 

Thanks, how to add compilation defines ?