Feedback Wanted: Visual Effect Graph

Feature Request (Unless this is already possible ;-) )

We frequently update: Unity, Visual Effect Graph, other packages ... and change between HDRP and Legacy. Especially the change between HDRP and Legacy requires re-compiling all VFX Graphs. I had assumed that a simple Re-Import would also re-compile them all, but that apparently isn't (or wasn't) the case.

So, at the moment, it seems I have to open each and every VFX Graph to make sure it is being re-compiled.

I think really, the expected behavior should be "recompile on Reimport". But if that isn't feasible, something like "recompile all my shader graphs" would be really important to have.

 

You can recompile all at once with a script included with the VFX Graph. Edit -> Visual Effects -> Rebuild All Visual Effect Graphs

 

By Connect Block, Julien Referred to the "Connect target" block (I advise you try it using the latest 4.8.0-preview as we did a bug fix). Connect block just stretches a quad so the top and the bottom are located at a given position, and a target position (you can use target position attribute for the target position). Then the quads can align differently (towards camera, towards axis, towards lookat position)

This is basically how we did the pin-screen in the demo, I have attached an effect with an example of these two features.

 

I want kill particles from constant spawner after N time, how to do that?

 

also
I want to start my particle slow and after 2 second rise it's speed.
So question is, how to properly sample whole particle lifetime?

 

"LoopAndDelay custom spawner"
yes, that work for me, particle correctly stop after n seconds. ty

Is the Age over Lifetime 0..1 a whole particle play time? What's mean every of this times?

 

Alright, I have a few questions with more definitely on the way. First off, how do the "Get Attribute" blocks work? It seems like once you switch them from current to source there's no way to choose the source it's drawing from which kinda makes them useless? Basically what I'm attempting to do is have 2 different particle systems where particles from system 2 spawn in the same position as particles from system 1 (with completely different behavior otherwise). The problem is I have no idea how to get the current position from system 1 plugged into system 2. On top of this, whenever I switch the "Get Attribute: position" block from "current" to "source" I get an error in the console (I'll add a screencap). Finally, one last thing, how could I set up a 2 particle system where particles from system 2 spawn when particles from system 1 die?

 

So, we got it working in Legacy! Yeah!!!

And as expected, performance is significantly better (also, it will be much easier to get the rest of this project properly working when we stay with legacy for now). We probably need to tweak the color grading and even with that, I'm not sure we'll get the exact same quality as with HDRP - probably not. But for VR, performance matters more than slightly better visuals. This is a prototype visualization for our upcoming VR game Beat the Rhythm (I put the HMD on a little chair to get consistent results):

[EDIT: Seems you can't easily watch this directly on Vimeo from this embedded video, so here's a direct link: Beat the Rhythm - The Singularity - VFX Particles Prototype on Vimeo]

In this video, we compare performance of VFX Graph 4.8.0, in Unity 2018.3.2f1:

First with HDRP (also 4.8.0), which does look a little better, but has unacceptable performance (this is on a GeForce 980Ti). Then, at 2:18, we use a build of the same visualization where we used Unity's legacy render pipeline - and even at the craziest particle counts (8x the particles count we had originally planned for), performance is butter smooth - not a single frame dropped.

One interesting thing about this is also that when we reduce the particle count to "basically nothing", we have 2-3ms per frame GPU time in legacy, and about 6-7ms per frame GPU time for HDRP. So, for now, it very much looks like HDRP will only really work for VR on very high end hardware (in other tests, rendering just a single cube, I got around 5ms or 6ms per frame).

I'll certainly give this another try with LWRP, once there is an implementation of VFX Graph for LWRP. But just as a data point, for me, HDRP is irrelevant for now, and legacy is all that matters (might become LWRP once that works but I haven't tried moving our project over to LWRP and it might turn out to not be feasible).

[EDIT 2: Ah, let me add some raw data:

Windows 10 (10.0.0) 64bit
Processor: Intel(R) Core(TM) i7-5820K CPU @ 3.30GHz --- Cores: 12 --- Frequency: 3298
Graphics device: 'NVIDIA GeForce GTX 980 Ti', vendor: 'NVIDIA'
VR SDK: OpenVR
HMD: Vive MV (HTC Vive)
Initial resolution: 1789x1988 (game SS: 1)

With HDRP:

[21:18:38.38 / 15s]
FXCount: 22, Spawn Rate Multiplier: 1.00 | Max Particle #: 425207, Avg Particle #: 223135
Max GPU Frame Time: 37ms, Total Frames: 1173, Dropped Frames: 0, Frames over 7ms: 1068 | 9ms: 74 | 11ms: 1

[21:18:53.53 / 30s]
FXCount: 22, Spawn Rate Multiplier: 1.00 | Max Particle #: 508720, Avg Particle #: 493339
Max GPU Frame Time: 10ms, Total Frames: 1343, Dropped Frames: 0, Frames over 7ms: 1073 | 9ms: 89 | 11ms: 0

[21:19:08.08 / 45s]
FXCount: 22, Spawn Rate Multiplier: 8.00 | Max Particle #: 2288908, Avg Particle #: 1159863
Max GPU Frame Time: 33ms, Total Frames: 901, Dropped Frames: 24, Frames over 7ms: 490 | 9ms: 456 | 11ms: 446

[...]

[21:21:53.53 / 210s]
FXCount: 22, Spawn Rate Multiplier: 8.00 | Max Particle #: 2430592, Avg Particle #: 2098061
Max GPU Frame Time: 29ms, Total Frames: 704, Dropped Frames: 60, Frames over 7ms: 704 | 9ms: 704 | 11ms: 592

With Legacy:

[22:02:42.42 / 15s]
FXCount: 22, Spawn Rate Multiplier: 1.00 | Max Particle #: 256335, Avg Particle #: 140388
Max GPU Frame Time: 21ms, Total Frames: 649, Dropped Frames: 0, Frames over 7ms: 1 | 9ms: 1 | 11ms: 1

[22:02:57.57 / 30s]
FXCount: 22, Spawn Rate Multiplier: 1.00 | Max Particle #: 512601, Avg Particle #: 440878
Max GPU Frame Time: 4ms, Total Frames: 1343, Dropped Frames: 0, Frames over 7ms: 0 | 9ms: 0 | 11ms: 0

[...]

[22:03:42.42 / 75s]
FXCount: 22, Spawn Rate Multiplier: 8.00 | Max Particle #: 2497997, Avg Particle #: 1170713
Max GPU Frame Time: 6ms, Total Frames: 1343, Dropped Frames: 0, Frames over 7ms: 0 | 9ms: 0 | 11ms: 0

[22:03:57.57 / 90s]
FXCount: 22, Spawn Rate Multiplier: 8.00 | Max Particle #: 2597701, Avg Particle #: 651528
Max GPU Frame Time: 6ms, Total Frames: 1343, Dropped Frames: 0, Frames over 7ms: 0 | 9ms: 0 | 11ms: 0



]

 

@jashan What was your setup to get it working in legacy? I tried a few things a week ago and nothing seemed to work.

 

Ty for quick responding!
How to choose random frame from flipbook? We can sampling flip book play speed only?
It's all about debris particles when explosion came

 

I can't find analogue of noise like with legacy particle system?
I found somethibg called turbulence, how to work with that? I want to simulate smoke after burning fuel.

 

@PaulDemeulenaere

Thanks for letting me know about Remap! Missed that one

Good to know, thanks.

So the above code looks like it would still cause an issue when it comes to simulating a fixed timestep system. It depends on how and where advancing the system is called. For simplicity's sake, let's say the VFX system is advanced with a simulate(dt) method:

Code (CSharp):

1.  
2. m_TimeAccum -= stepsCount * m_FixedTimeStep;
3. stepsCount = clamp(stepsCount, 0, (int)m_MaxFixedTimeStepCount); //m_MaxFixedTimeStepCount computed from m_MaxDeltaTime (default, 1.0f/20.0) & m_FixedTimeStep, thus, default is 3u, this clamp leads to a slower simulation when we didn't reach target frame time
4. float actualDeltaTime = stepsCount * m_FixedTimeStep; //At this stage, actualDeltaTime should be between [0.0f, m_MaxDeltaTime]
5.  
6. // This would be unstable, because actualDeltaTime is now variable (between m_FixedTimestep and m_MaxDeltaTime)
7. // simulate(actualDeltaTime);
8.  
9. // This would be stable, as dt will be constant within the system between frames
10. for(int i = 0; i < stepsCount; ++i)
11. {
12.     simulate(m_FixedTimeStep);
13. }
14.  

 

Hi Andy,

The important thing is to use a current version: They've had a typo in one of the shaders that caused shader compilation errors a few weeks ago. So, I used Unity 2018.3.2f1 and Visual Effect Graph 4.8.0.

Then, all you need to do is Edit -> Project Settings, select last section in that panel: VFX and for Render Pipe Settings Path put in: Packages/com.unity.visualeffectgraph/Shaders/RenderPipeline/Legacy (instead of Packages/com.unity.visualeffectgraph/Shaders/RenderPipeline/HDRP). So basically replace HDRP with Legacy)

And after that, make sure to recompile all VFX Graphs in your project, using: Edit -> Visual Effects -> Rebuild All Visual Effect Graphs (thanks to @Grimreaper358 for making me aware of how to do that).

Just to be sure, I also restarted Unity. That never hurts ;-)

There are some limitations with legacy; IIRC one was that VFX Graph does not support lighting with legacy. See posting #248 by @JulienF_Unity for the limitations with legacy support.

 

frames from flipbooks are selected using the `texIndex` attribute (integer part selects the frame, fractional part is used for the blending when using flipbook blend mode in your output.

to start your particle at a random frame, you can use a `set texIndex` block and change the random mode to uniform in the inspector.

if you need to play an animation, I'd suggest you use a `flipbook player` block in update or a `texIndex from Curve` (over life) in update/output

Turbulence is one way to go indeed, it applies procedural 3d noise based on particle position. As you increase drag, the force will proportionally become the particle's velocity.

Other method is using Vector Field Force (if you have 3d vector fields, otherwise i'd advise you get some files here)

If you are still not satisfied with these methods, you can also compute your own procedural noise using Noise Operators, then plugging these into a Force node and do the math yourself

You can push the particles a bit towards the camera by using the `Set Pivot` block in output, the Z component pushes towards/away the particles based on their normal. To avoid particle shifting while moving them towards camera, I advise you use the orientation "Face Camera Position"

Hope that helps

 

Ty for helps. Another question packages here:
1)Is there any way to rotate world space vfx system via unity transform through inspector?
2) How to play flipbook only 1 time (there is video which show my issue
3) How to set random position for every particle?

here you can look at wip's vfx

 

What happened to the block: "Trigger Event on Die" that they showed off in the genie demo? Apparently it doesn't exist in the VFX graph anymore. Is there some other way to trigger an event on die now? Also I would really appreciate it if someone could answer the previous questions I posted.

check it out in their example:

 

Greatings! Does it exist way to add more variation to explosion, something like random horizontal flip?

 

It's part of the experimental blocks.

In the preferences (of Unity) under visual effects you can check experimental blocks and then it will be available.

 

@jashan Thanks so much for your help. That worked for getting legacy working.

Question for Unity staff - is there an ETA for LWRP support for VFX Graphs? Is there an experimental branch that supports it?

I took a look on Github to see if any branches had LWRP files inside \com.unity.visualeffectgraph\Shaders\RenderPipeline but couldn't see any. Am I correct in thinking that this is the right place to look for signs of support?

 

I have short life time effect called muzzle flash it's life time 300 ms and another effect called "exhaust smoke" it's life time 2 sec, I want to trigger muzzle flash and smoke seperately via c# code
Is there any way to trigger resimulate only part of vfx graph?

 

update i found that. Just create Event onPlayCustomName and trigger it via code
every 300 ms send event (OnPlayFlash)
every 2000 ms send event (OnPlaySmoke)
also make onstop even for it

 

New problem here. How to make smoke trail for rocket? I need spawn one particle =rocket give it very fast movement and attach to them smoke.
1) How to get position and velocity of rocket?
2) How to spawn smoke trail on rocket trajectory?

 

Thanks Tomas for explaining, that really helped. A problem appeared the last few days, hope someone could help me:

I've been using the Turbulence block for the last days, which works really cool. I'm positioning two million pixels (1920x1080) across the screen, and with turbulence I 'morph' a texture. (In theory I just map the particle color based on the UV coordinates)

After the morph is done, I lerp the particles back to their original position by setting the target position to their own position on initialize.

One problem that keeps occuring is that after a while, only when I use the turbulence, the particles don't move back to their target position. They either disseapeared, or 'forget' their target position. I am not setting any lifetime, so I assume that the particles don't die.

I've made a gif of it, if the quality is too bad to understand, I can create a better one.

https://i.gyazo.com/9bc4d809e91ce5057120e0f02a5feb32.mp4

The pink is the background, the dark grey are the particles. In the first 10 iterations or so, you don't notice the gaps, but the pink spots grow bigger and bigger over time.

 

A new mode would be great (this would be pretty hard to handle on the user end since it means the passes all need to run multiple times).

At the very least I would consider renaming it as it's not in line with typical expectations with fixed time (including Unity's own 2D and 3D physics).

 

So maybe I'm missing something but I can't get this to work:

I wan't my particles to change color over life based on a gradient, but I want this gradient to come from a property that I can set.

So far so good, I create the property and set this to the gradient of alpha/color in quad output.

But, what I want is that when I change the gradient is that this only applies to new particles. Doing this in the quad block changes it for all particles in the scene.

I would have guessed that adding a color over life block in Initialize would do it, but this only seems to set the particle color to a fixed color. It does not change.

What am I missing here? Shouldn't the color over life move through the gradient?

 

You could try sample gradient with age or something, but I'm not sure that's what you want, cause when I change gradient this still changes the appearance of existing particles. On the other hand, for this not to happen, it would be necessary for each particle to remember its gradient, and this is not very effective from memory perspective, isn't it.

 

Up that question

 

I think I get what the problem is, it is indeed not storing the gradient information but only the color and alpha of the particle. It is a bit confusing because it lets you set Color over life during initialization, but it seems to function more just like Set Color.

It is a bit annoying because it seemed like the easiest way to have a particle change color over life based on the situation when it spawns.

 

You could do the following (you'd need to enable experimental custom attributes in preferences):

1. Set a "startColor" attribute in the Initialize context, based on sampling your gradient
2. In the Output context, set color from the custom attribute "startColor"

Changing the gradient from script (or in the editor) would then only change newly emitting particles.

 

yo devs, maybe we organize vfx graph discord group?

 

#Vfx_hint
Use add velocity (Direction) instead add velocity and you will able to rotate gameobject transform when world space simulation used

 

Node setup to play flipbook animation only 1 time, when it reach last tex index of your flipbook it kill particle

 

Random particle flip along y axis

 

The way how to add delay to constant spawner. Use random spawn factor also

 

How to get position from another particle system that into one graph?

 

Hi! Could we import Houdini rdb stuff into unity visual effect graph? Like what was shown in this video:

 

Up tha question agan

 

Hi guys, any idea how to set the old shuriken Prewarm into Visual Effect? Thanks

 

Does anyone get entirely different particle behaviours when they restart unity? Sometimes I get an accretion disk, and sometimes I just get a chaotic ball .

 

Is it possible to download VEG as package and put it in project folder ?

 

Please add able to share update context beween multiple diffrent Initialize context, I have many simillar context chain, that difference only in spawn and initialize contexts. there is void update. It's will work way much faster if it share one single update like this

 

Three suggestions that would make the newbie experience better

1. Add to the compatibility section of the sticky post for this forum to included the recommended (most stable) package versions of related/required packages (e.g., HDRP, Shader Graph). After successfully working with the sample project, I tried updating those packages to the latest versions, and the project went nuts.
2. VFX wiki table of contents on Github. The wiki page for Visual Effect Graph has great links to the key content but there's also a "Content" outline nav box that goes to other stuff like Shader Graph where it's easy to confuse the Shader Graph "Node Library" with the VFX Graph "Block Library". I was looking for info on a "flipbook node" and got lost
3. I'm guessing the majority of VFX graph users are pretty advanced users of Particle Systems, and I think there's going to be an endless stream of "how do I replicate what I used to do in a particle system in the new VFX graph?" So that might be a good approach for tutorials/docs to just go module by module through the legacy particle system to show how to do the equivalent in VFX graph. For example, there's several posts in this forum about how to work with Texture Sheets, and it's still not clear how to do all the common tasks in the new system.

 

Maybe some of may post will help you. I've found way how to set random tex index at spawn, how to play flipbook only one time.

 

Your posts are certainly helpful. The suggestion I was making was a way to componetize the teaching more efficiently than surfing an ever-expanding forum. The node library for Shader Graph does this well. Here's an example for picking a random Texture from a texture sheet.

 

join in our discord vfx graph, let's learn this tool together!
https://discord.gg/KkSUGRn

 

So I managed to get what I wanted working based on this.

What I really wanted was just a way to create a gradient from two colors that are fixed on initalization, but there is no way to create a new gradient. The only input for a gradient node is another gradient.

So the creative fix was to use SetColor in initialize and sample from the gradient at time 0, and then use SetAttribute to store a Vector3 (i think 4 should also work for alpha but I had some strange issues). In update I then use blend color and GetAttribute for the color and Age Over Life with a divide to control the gradient over the particle life.

After this a gradient as input is not really needed anymore and it can be swapped out for two color parameters, saves the sampling as it adds nothing when blending between two colors.

I also started looking in to creating a gradient from color operator but it seems like a real hassle with everything being internal and the actual operators seem to be an enum? Maybe they start supporting extensibility over time.