Feedback Wanted: Visual Effect Graph

Thanks for the clarification on index. Great to hear that you'll be adding spatial partitioning and random read access as well—we made some code to specifically do that in fact.

It sounds like once these steps are taken (and an API is finalized enough to be public by default), we should be able to do everything with some vanilla C# and no reflection.

Although I do have a question. How would you approach spatial partitioning by just using the particle buffer? Unless I'm mistaken, doesn't that buffer have a size of n * dataSize where n is particle capacity (aligned maybe) and dataSize is the amount of data per particle?

In old Fluvio, we used an infinite grid structure with a size of x * y * z * maxParticlesPerCell, which is a completely different size than the particle buffer. We also used another buffer with a size of capacity * maxNeighbors to store the neighbors of each particle for subsequent steps of the simulation.

Ignoring traversal concerns, I guess you could do some sort of sparse structure where we store an index per-particle (and this would save a ton of memory), but I'm not sure how we'd work around the issue of neighbors. Especially since we use multiple kernels (update contexts) for sync, and need that neighbor data for several steps.

 

I have been playing around with linking exposed parameters to UI elements like sliders and so far so good, but I ran across this section in the API that I am not sure I understand. It says...

"Every function can refer to a parameter using either a string name or an int nameID. If you need to perform access to these parameters on a per-frame basis you should cache the name and perform calls with the ID using Shader.PropertyToID()"

I am calling the exposed parameters by name right now and it is fine, but if I wanted to have the property be updated every frame I am not sure how to use the instructions correctly in this context. Any insight or code examples floating around for this?

 

Oh my God - you just made my day. No. Week. No. Month! ;-)

Only unlit outputs is no problem for us: The use case we have is a purely particle based reality so we might not even have lights in the scene. The big issue we were facing was that this is for a fairly old project (currently still on 2017.4 and I am waiting to upgrade to 2018.3 or 2019.1 until the very last moment because I expect a lot of trouble) ... and from what I have seen with HDRP so far, it's fine if you begin a new project with it but moving a large legacy project to HDRP might kill the project. Plus, it's a VR project, and so far, it looks like HDRP adds way too much overhead, so we're more likely to go with LWRP at some point but most likely will keep using Legacy until we absolutely have to move on.

With the typo in Legacy fixed, I can test if our 2018.3 prototype project works with Legacy, and if it does, put the two things together and finally push out a demo ;-)

 

Feature Request: Moving back in Time

In our project, one fun feature we'd love to implement is the ability to arbitrarily move back and forward in time while doing session replays. At first, I thought I'd have to create a custom implementation to make this work for audio, and there is one small thing that we do have to do - but that's almost trivial (negative pitches do work, how cool is that!? ;-) ). As most of our game logic already uses AudioSource.time instead of Time.time, a negative pitch means that we already can move backwards in time.

One trickier part is being able to revert our Visual Effects. I did a little experiment with setting playRate to negative values - but that only stops everything. It's probably clamped to 0 internally.

Is that something that would even be feasible?

One obvious requirement would be that everything is deterministic, and we would need to be able to set a "simulation time" so that, for example, when time is passing at -1, an effect that usually only lasts 2 seconds would be instantiated / started two seconds "before" it starts, then played backwards for two seconds, then "disappear".

Internally, the same would have to be done for each individual particle. But the cool thing is that it would allow "scrubbing" complex effects back and forth during design time, too, so I think it would be a rather useful feature to have beyond our rather specific use case. There are obvious limits to feasibility: When there are forces involved, you'd need to know the past (which from that perspective, really is the future ;-) ).

 

Ah I see I had missed new stuff a couple of days ago again because it was mostly mentioned on twitter and not on the forum....

Additional sample scenes added to the sample project:

https://github.com/Unity-Technologies/VisualEffectGraph-Samples/releases/tag/4.6.0-preview-rev1

 

All fantastic stuff! I'll get in touch via PM.

In general, I am so excited for the new open direction Unity is taking with packages, with great consideration to a variety of use cases. How great the VFX system is to work with really shows here.

 

Feature Request/Bug Report: "Orient: Along Velocity" should only rotate around Z axis.

I'm not sure if "Orient: Along Velocity" behaves like it should. Currently it doesn't always point particles to the camera. This sometimes makes them infinitely thin when they change direction.

I use "Orient: Along Velocity" to fake motion blur on fast moving particles, by stretching them along the axis they're moving in. But I also want the particles to always face the camera, keeping their original size and aspect ratio.

The solution to this would be to only orient the particle based on its velocity on the X and Y axis relative to the camera. So, first do what "Orient: Face Camera Plane" does, then rotate the particles around their Z-axis to point in the direction of their velocity.

Is this possible? Thanks

 

OK, that took me a minute to grasp, but once I read the documentation about Shader.PropertytoID(); it made more sense. I am wondering though about these exposed properties though. Right now in order to access them with a slider I am having to re-assign them with a script in order to get them to show up as a non-static variable to the UI components. It's not the worst thing, but it's an extra step,..

 

Thanks for taking the time to look into and fix it, very much appreciated!

 

@VladVNeykov I actually went with AngularVelocity as I wanted random numbers between both positive and negative rotation. I have not seen how to a random between two curves in the VEG....am I just missing it? However now I notice that also that AngularVelocity doesn't seem to care about physics at all. I'd love to be able to change the angular velocity based on collision for example.

Feedback: A gizmo representing a turbulence block would be pretty helpful.

 

Hi all,

Quick question on preventing the culling of particles:

I have a single burst of particles with an infinite lifetime that is attracted to another object. This object moves away from the VFX game object, and the particles are culled when the VFX game object is not in the camera's view.

How can I see the particles when the VFX game object is not in the camera's view? If I attach the VFX game object's transform to the attractor object, then the particles do not physically move correctly (they are translated but the particles do not have any drag).

Cheers!

 

Try to extend bounding box

 

I wonder can I do something like this? Not about collison, but just not render particles in special areas.



And how?

 

Is there a way to lerp the position of particles between two point caches?

 

Hello! I am trying to use Visual Effect Graph to make some point-cloud style visuals.
This is what I want to achieve: point cloud with its colors!
I can get this colored point cloud with the MaskFace PointCacheAsset from the official sample project:

I want to use other models and I downloaded a beatiful 3D scanned obj file ( "More Model Information" says that it contains vertex color) from this site

I imported this obj file into Unity, and used pCache Tool to generate a pCache file. Below are my settings:

When I replace MaskFace PointCacheAsset with the PointCacheAsset I just generated, there is no color on it!

I was wondering if I did something wrong or I misunderstood something. It would so great if anyone could help! Thank you!

 

Hey Guys,

i am trying to access via c# the exposed parameters of the visual effects graph. But i don`t know how to access them. I don`t really understand the official documentation to it. What i actually want to do is to control an "exposed" float via Script. I have enabled the "expose" option in the graph for an float, but can`t find the variable. The script is attached to the gameobject where the visual effect object is attached to.

With this code i get an "Null reference exeption".

Any help is appreciated!

Code (CSharp):

1.  
2. using System.Collections;
3. using System.Collections.Generic;
4. using UnityEngine;
5. using UnityEngine.VFX;
6. using UnityEditor.VFX;
7. using UnityEditor.Experimental.Rendering.HDPipeline;
8. using UnityEditor.VFX.UI;
9. public class particleMainScript : MonoBehaviour
10. {
11.     UnityEngine.Experimental.VFX.VisualEffect visualEffect;
12.     float exposedParameter;
13.     void Start()
14.     {
15.         visualEffect = this.GetComponent<UnityEngine.Experimental.VFX.VisualEffect>();
16.         // exposedParameter = visualEffect. -> what to insert here to access the expoosed parameter?
17.     }
18.     void Update()
19.     {
20.         if (Input.GetKey("down")){
21.             visualEffect.Stop();
22.         }
23.         else
24.         {
25.             visualEffect.Play();
26.         }
27.     }
28. }
29.  

 

I opened the .obj file with Notepad. There is color information:


I also opened the .pcache file generated with pCache Tool. And I found that the colors become 1,1,1,1 or 0,0,0,0 or even 0.99999


I tried several different settings in pCache Tool but no good.
Hope someone would shed some light on this!

 

In order to do this, you need to include using UnityEngine.Experimental.VFX;
Then I assigned public variables to things I wanted to change with say a UI slider, and then you can use _vfxobject.SetFloat("exposed parameter name string", float value);

I could not find a more direct way to access them for a UI element as I needed public non-static floats for those.

Here is the example I made with it...

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEngine.Experimental.VFX;
5.  
6. public class VFXVariable : MonoBehaviour
7. {
8.  
9.     [SerializeField]
10.     private VisualEffect _vfxObject;
11.     [SerializeField]
12.     public float _spawnrate { get; set; } = 250f;
13.     public float _turbulence { get; set; } = 0.2f;
14.     public float _gravity { get; set; } = 0f;
15.  
16.  
17.     private void Start()
18.     {
19.      
20.     }
21.  
22.     private void Update()
23.     {
24.         _vfxObject.SetFloat("variableSpawnRate", _spawnrate);
25.         _vfxObject.SetFloat("turbulenceIntensity", _turbulence);
26.         _vfxObject.SetFloat("Gravity", _gravity);
27.      
28.  
29.     }
30.  
31. }

A video of the result.

 

Also, for anyone who is curious, VectorRayGen plugin does work to convert standard .fga files into something VFX graph can understand. It just works. The fact it can also affect Rigid Bodies or CPU particles is a bonus for sure.
This gives some interesting things to play with as you can chain multiple vector fields in the update.

 

Feature Request:
add node to sample SDF for procedural shape(box,sphere,2d circle etc), in addition simple SDF generated from list of sphere.Also add node based editor for procedural SDF to do animation and do other operation to SDF(mainly focus SDF)

 

I do not understand where is parameter for particles use light probes.(in graph or whatever) When I first time add prefab with particles to the scene I see the “VFX Renderer” window and I can even change this parameter, but after applying the prefab, it's break on zero again, and this window are disapperear. I can see changes in the prefab, but after add this prefab on scene - parameter is zero again. What kind of magic is this?

 

Hello!

I was messing around with the VFX Graph, trying to replicate the look / behaviour of some Particle Systems I had here in order to get the hang of it.

However, it seems that some of the things that are available in the Particle System are not in the VFX Graph - things like Trails, dampening speed / velocity, choosing the color from more than one gradient and Lights, for instance.

Is there any way to add those behaviours to the VFX Graph? Do I need to "make them by hand" via the nodes, will they be added in the future, or would I need to add them myself via C# when the API becomes public?

 

How to start drag particle after 2 second?

 

Hm, is there any way to bake a VFX system (or any plans to implement this)? I'd love to experiment with simulating VFX and then baking the data (sacrificing interactivity) for later playback.

 

Hi VladVNeykov,
Yes, I think you're right!
I think the obj file does have vertex color because I can see the color information when I open it with Notepad. I can also see its colors in MeshLab.
However Unity can't import vertex color from obj files.

I export the obj in dae format with MeshLab. And Unity can import the colors from the dae!

I used pCache Tool to convert this mesh to a pcache file. With this pcache I can display the colors on the point cloud now!
Thanks a lot

 

Hey ! I am currently downloading VFX Graph in order to try it but I have a compilation error so I cant do anything.

Unity Version : 2019.1.0a13
VFX Graph Version : 5.2.3

Error :

"Library\PackageCache\com.unity.visualeffectgraph@5.2.3-preview\Editor\Expressions\VFXExpressionTransform.cs(64,47): error CS0117: 'VFXExpressionOperation' does not contain a definition for 'InverseTRS'"

In VFXExpressionTransform.cs :

class VFXExpressionInverseMatrix : VFXExpression
{
public VFXExpressionInverseMatrix() : this(VFXValue<Matrix4x4>.Default)
{}

public VFXExpressionInverseMatrix(VFXExpression parent) : base(VFXExpression.Flags.InvalidOnGPU, parent)
{}

public override VFXExpressionOperation operation
{
get
{
return VFXExpressionOperation.InverseTRS;
}
}

sealed protected override VFXExpression Evaluate(VFXExpression[] constParents)
{
var matrix = constParents[0].Get<Matrix4x4>();
return VFXValue.Constant(matrix.inverse);
}
}


this line ".InverseTRS"

what should I do ?

 

How would you go about spawning particles from particles? I am thinking of something like fireworks. you could have some particles shooting up into the sky and when they reach the top they explode by spawning a bunch of new particles. These new particles could have different effects on them like gravity. Also you could use a system like this for volumetric clouds. i'd imagine you could use particles spawned across the sky to be cloud seeds and from each cloud seed you could have a cluster of particles spawn around it which would be the cloud itsself, including motion inside themselves. but the clouds could be moving across the sky as the cloud seeds would be pushed at a certain rate.

How would I go about achieving this?

 

Someone here asked about the target position from map, and I would really appricaite if soemone can eleborate on that.

What does the 'connect block' exactly mean? How is it used? I would like the particles to flow to a specific point, based on an attribute map. Is that possible with the target position?

Thank you so much.

 

Hello all,

Has anyone written a script to trigger an event send so that particles spawn upon mouse at mouse click location? I thought this would be easier than it's turning out to be.

Thanks in Advance!

 

Hm...

https://github.com/Unity-Technologi...2cc9/com.unity.visualeffectgraph/CHANGELOG.md

I know it's early but is there a quick summary of changes (even informal) somewhere?

Noticed the jump in required Unity versions between 4.x and 5.x, seems like something enabled by new engine updates? EDIT: Just saw @PaulDemeulenaere's reply above, looks like 5.x is for 2019.1 and not published yet.

 

What particle material is VEG using as default ?

 

This is all very nice, but where is parameter for light probes? I can't find any.

 

Would it be possible to add an inverse lerp node? I find myself having to do multiple nodes for

f(x, a, b) = (x - a) / (b - a)

quite a bit.

 

***EDIT*** Nevermind, downgraded HDRP 4.8 to 4.6 and reimported the Visual Effect Graph folder, errors went away and remaining CS files imported into Unity.
-------------

getting some errors on adding the VFX Graph package with HDRP in 2018.3.2f1

a few of these:
"Shader error in '[System 1]Initialize': failed to open source file: 'Packages/com.unity.visualeffectgraph/Shaders/Common/VFXCommonCompute.cginc' at kernel CSMain at System.vfx(14) (on d3d11)"

The cginc file is at the location, is VFXGraph 4.6 outdated? (do the package include paths need to be changed?)

also getting errors finding PCache:

Library\PackageCache\com.unity.visualeffectgraph@4.6.0-preview\Editor\Utilities\pCache\BakeTool\PointCacheBakeTool.Mesh.cs(375,9): error CS0246: The type or namespace name 'PCache' could not be found (are you missing a using directive or an assembly reference?)

PCache.cs is in PackageCache\com.unity.visualeffectgraph@4.6.0-preview\Editor\Utilities\pCache

but PCache.cs PointCache.cs & PointCacheAsset.cs do not show up within the Unity project view (despite all 3 being in that folder)

 

I apologize, but what do I need to do in order to finally get a working "Visual effect graph" I have reinstalled Unity for three days already, set 4.3, 4.6, 4.8. I tried to install HDPR first, and already VFX after it, installed different versions and tried combinations of versions, I did not see any information on the forum, maybe I missed it. Please help to make it work for me. Now I have 2018.3.2f1, which version I need to install Unity and which versions of HDPR and VFX I need to install in it, and in what sequence. Thanks in advance, sorry for google translate.

 

Did you set the render pipeline asset in graphics settings? (you can create one from the Assets menu)

 

Thank you so much, now I see that I missed

 

Hey, can't figure this out, so can anyone hint - how to actually use event attributes?
I tried it like this:


And now I wonder.. How do I get spawnPos in VisualGraph?
I want to spawn particles in a certain position via script. Right now, as workaround, I just set exposed parameter without eventAttribute and then call event.

 

Hi there, i've found some reaaaly strange bug with hdr color via vfx editor. after 7.69 hdr instensity. Looks like hdr color clamp bug.


please hot fix.
I need such intensity in terms of physical correct lighting units:
100k for sun
15k for sky
and PPV
dynamic range -9 to 9
exposure compensate to 0.05
also some video heare

 

Hm, seems I found a bug!

Fixed timestep and deltaTime are being calculated incorrectly when maxDeltaTime is higher than deltaTime. (or am I missing something?)

Typically, for fixed timesteps an accumulator loop would be run (exactly like Unity's 3D and 2D physics):

• Accumulate frame deltaTime each frame
• Once the fixed time has passed, simulate and subtract from the accumulated time multiple times, until it is again under deltaTime.
• Don't simulate more than maxDeltaTime (to prevent simulation from blowing up when it isn't realtime)

The key here is that each time particles are simulated, the same deltaTime is passed every single time.

Instead it seems like this is happening:

• Accumulate frame deltaTime each frame
• Once the fixed time has passed, simulate the accumulated time once and reset the accumulator to zero (even though the last frame may have been longer than the target time)

This makes for unstable simulation (since integration can happen larger timesteps), which can be noticable if you have a ton of non-linear forces being applied.

The current workaround we have is to set both timesteps as the same, but this makes simulation slow down if we dip under our target time.

Also a quick question: should I be making bug tracker #s for this (or Unity's other experimental features)?