Sub Mesh Mask per Particle

For a VFX Graph, I want to output random meshes and tried to play around with the Sub Mesh Mask option of a Output Mesh block. While I was able to input per-component values, I got errors as soon as I entered per-particle-values (like a Random PerParticle, age attribute or texIndex attribute node).

...Exception while compiling expression graph: System.InvalidOperationException: Unable to compute CPU expression for mapping : subMeshMask...



I guess its by design that an output block can only render a single selection of meshes for all the particles?

The only workaround that I came up with was to duplicate the output node, set the Sub Mesh Mask manually and randomly scale the outputs to hide all but one.

Any insights on this?

 

Thank you for the swift clarification!
I went with your proposed workaround for now. It didn't negatively impact performance too much so far.

 

Any updates on this? I'm trying to animate the mesh of a particle by playing through different submeshes

 

+1
Any updates on this ?
This is quite crucial if one want to switch between a large number of different meshes (.i.e having 24 copies of the output block isn't practical )

 

@JulienF_Unity
Are there any updates on this feature ?

 

Hello, that feature is welcomed indeed. But what about the sub-mesh mask. Would it be possible to manipulate the sub-mesh mask per particle at runtime in any way? Let's say someone would use this to hide parts of a particle geometry. Sure, it can be done with different output but could it be done any other way?

Something like this: (use the sub-mesh mask to hide bits from the geometry)



edit: Also, I found out that there is a seemingly arbitrary limit on how many outputs a particle can have before "System.InvalidOperationException: Too many contexts that use particle data" is thrown. So I can't go too crazy with those either.

 

[I haven't tested it] Cant you just create custom attribute or use existing (but not used) one like texindex to plug it as sub mesh mask?

 

Nope, does not seem to work. It throws an exception and shows me a message like this:

 

Oh right, dumb of me... GPU must have mesh loaded beforehand.
Not sure what exactly you need, but instead of hiding sub meshes in vfx system what if you modified referenced mesh - you would combine or modify mesh in C# (or maybe compute shader can do this?).

 

Well, I wanted to use a point cloud to feed sub-mesh masks to each individual particle. The idea was to disable parts of a already split mesh to chop trees in a vegetation system, for example. So whatever the solution is, it must be able to work per instance. I could use multiple outputs instead, but it's not too pretty or efficient.

 

Yeah, that might be an option as well.

 

2024 - still waiting for this feature...

Can't imagine putting a check in the vertex shader and outputting "position.w = -1" if it fails is such a big deal.

 

@OrsonFavrel I ended up writing a custom shader, where I set position to zero if conditions are not met. Meshes are distingueshed using vertex color