[Visual Effect Graph] Spawn particles from skinned mesh surface

Hi,

I'm playing around with the VFX graph samples, and while the point cache approach is really nice for static meshes, I can't find a way to spawn particles on the surface of animated / skinned meshes.

Is there a way to randomly spawn particles on the surface of a mesh other than the standard primitives?

 

Great We will wait for these features before commencing any heavy VFX work on our characters. Our game is scheduled to be released in 2021 anyway, so we're most likely to ship with Unity 2020.X.

 

Can we expect skinned mesh sampling in a later version of 2019.3? I had a look at the release notes & played around with the latest version but couldn't find any references to it. Very excited for this feature

 

Hi, does this still stand? Got the beta but can't seem to find this functionality.

 

I'm equally interested. Can't seem to find this in 19.3

 

Is there any update on this?

 

Any news on this?

 

Any update on this?

 

I can't seem to find how to use a static mesh as an emitter, is this in 2019.3 yet?

 

@JulienF_Unity

Can't seem to find this in 2019.3... as many have already asked what's the status?

 

Me neither... Would love a feedback on this !

 

I needed this too, any update? is on the roadmap at least?

 

Are there any news regarding?

 

@JulienF_Unity Any news about that?
Does it will be implemented for 2019 LTS or only 2020 now?

 

@JulienF_Unity Any update on this? Even static mesh sampling would help me move over a few more of my particle systems to VFX graph

 

For static meshes you can either bake a point cloud or a signed distance field.

 

@alexandre-fiset Thanks for the suggestions, unfortunately my vfx graph spawns particles from a mesh that's generated at runtime, so using unity's bake tool for point clouds isn't going to work. I could try to process the data async and generate it myself, but given the vertex data is already on the GPU with the mesh, I'd hope I could just use that existing vertex buffer as a point list to draw from.

 

One year later and still nothing.

 

1 year anniversary!!!!!
In all seriousness, it'd be nice if we could get some kind of confirmation that this feature is either delayed or cancelled so we can all move on

 

Next year for sure.

 

Still nothing? I'd really love to use something that was built into Unity. It's a bit of a hassle installing and using Keijiro's tools. I've had some errors.

 

On a side note, does anyone here know how to rotate (over time) a point cloud "emitter"? It seems that a static point cloud would handle rotation, but all I see is scale and translate x,y,z. Thanks again.

 

Can't find static mesh sampling in 2019.4 / 7.3.1. Can you really not emit particles from the surface or volume of even a static mesh in VFX Graph?

I can't use the point cache baking utility because these meshes are procedurally generated at runtime. This was an important feature of Shuriken.

 

if it helps you i had the same problem with my procedural spawned terrain. I just used the same height map in my vfx graph to spawn grass

 

epic lawl bump

 

We need info about it.

 

Necro-resurrection: is the VFX graph prev 10 only supposed to support static meshes? (considering smrvfx or prev 10 for a project)

 

Apparently the skinned mesh sampling is in 2021.1. Did not try it out though but would be curious to know if that works well!

 

Anyone having too much time?

 

Just checked, was added in 2021.1.0b10/2021.2.0a9
Looks very promising!

Now to figure out how to use it...

 

did you figure it out? also, where are you seeing this node? can't find it in the same version (URP)

 

You might have to enable experiemental blocks in preferences/visual effects. I attached a skinned mesh on init, it works like the previous mesh, but so far i can't get it to update / animate. If I put it in the update node it gives strange results.

 

Yeah as mfolsom said you need Experimental Operators/Blocks enabled.
I've managed to achieve good results with a Position (Mesh) block with its Source Mesh setting set to SkinnedMeshRenderer, but haven't yet figured out how to replicate its behaviour with the Sample Mesh operator in order to get outputs other than position.

 

thanks for the helpful replies! alas, I'm blocked by the fact both versions seem to fail to build to Quest using Vulkan - crashes on start - which means I have to stick to the previous Unity version and perhaps Keijiro's solution (https://github.com/keijiro/Smrvfx). But I'll give this a try as soon as these crashes stop happening!

 

Since nobody answered I'll necro this, you can transform any set of positions by using Get Position Current > Transform Position (use the transform fields to manipulate) > plug into add or set position block.

 

Wish I'd seen this tweet from Paul Demeulenaere sooner! Exactly what I was after
https://twitter.com/PaulDemeulenaer/status/1376977896309465095

 

Now that it appears to be supported in 2021.1, is there any chance of seeing that feature backported to 2020 LTS?

 

Hello all ! I'm using this wonderful feature to sample mesh in realtime. But, I wonder why it is not available to emit from a volume instead of surface, vertex and edge.
Any idea why ?
(because actually I would exactly emitting from a volume like the basic geometry we had before)

 

You can approximate it by manually setting a pseudo pivot point (or even calculate an average, but then mesh density affects the pseudopivot) and lerp the particles towards that by a random amount.

 

Thanks for your answer ! It is reaching my algorithmic limit
Do you have any clue to calculate this pseudo pivot point ? a method ?

If I follow you, this will work for concave mesh and not concave. If I take a torus for example, its pivot point is its barycenter. And I lerp from here between each point of the mesh, I will end up emit inside a thick disc. Right ?

 

There are several ways to go about that, and the way you should go about it has primarily to do with indeed the shape you're trying to achieve.

Calculate the object center on the CPU (for simple shapes you could take an objects bounds center for example) and send it to the VFX graph via a texture / spawnEvent / Property(just like shader properties, they're the same thing for the most part infact) etc.

Alternatively you could add all the vert positions to a single variable relative to zero then divide by the number of verts etc.

For a convex shape you can quite literally indeed do a weighted lerp and you're done.
For primitives / simple shapes like a torus, you could instead spawn them in a circle, then add random position.
For complex concaves there is the option of doing primitive shapes "stickman" shaping of the object and adding randomness to the positions.

For a surface thickness instead of full object volume you can just multiply the positions by adding random position to them, but always in the direction of the center you want. If you need more than one "center" point you could add randomness towards, you can use lerp T inputs combined with distance from manually placed points as to how much random value you add, then add them together. (you can use clamped remapping for example to prevent values inverting when they're outside the area).

I would strongly suggest prototyping, a good exercise on how to do it i would recommend for example spawning particles in a cone, then using the particles Y position to lerp with how much position to modify, then progress to having two different spawn shapes by using probability sampling & switch nodes for example (assign an ID for each particle with probability sampling via custom attribute, then Get that for the switch and you can pick / choose how many spawn from cone vs other shape for example).

And if you're not spawning ludicrous amounts of particles per frame, you can do some insanely complex math in initialization, update is what kills you, so try to store all the data you can in init and only use what you must in update if you need very high performance particle systems.

If you have an actual specific problem you need help with, post it or pm me.

 

How buggy is it? Or ow many hours to get all console errors away? knowing unity's betas packages...