How to Retain All UV1 Data in a Mesh When Using It in ParticleSystem?

Is there way to retain the data in mesh's UV1 when using ParticleSystem with "Mesh" Render Mode?

My vertex shader struct looks like this:

float4 vertex : POSITION;

float3 normal : NORMAL;

float2 uv : TEXCOORD0;

float3 data : TEXCOORD1;

The shader works fine when using with MeshRenderer, it only doesn't work when using it in a particle system.
Does anyone know any solution to this?

 

There are two options for this:

You can use an instanced mesh particle system shader, in which case you have access to the original mesh data unmodified and get all of the per-particle data via instance data. Note that GPU instancing for particles is different than GPU instancing for "regular" shaders and requires a very custom setup.
https://docs.unity3d.com/Manual/PartSysInstancing.html

You can use custom vertex streams to get the

xy

values from

TEXCOORD1

, but I don't think you can get access to the

z

or

w

value, so you'd need to pack the data across

TEXCOORD1

and

TEXCOORD2

.

The above example takes the

xy

values from the original mesh's

TEXCOORD1

and packs it into the

zw

of

TEXCOORD0

of the mesh generated by the particle system. This does mean the shader used on a non-instanced mesh particle and used on a non-particle mesh cannot be the same.

 

Looks like there is no way to pack another float3 or float4 into a non-GPU instanced mesh particle without giving up normal, tangent, etc.

 

A bug report was submitted.
CASE 1397475

 

Yes, all 4 UV streams are exposed, but in Mesh render mode you can only choose a maximum of 2 UV streams at a time, so with UV1 already in use for texture coord, you cannot access any other data more than a float2 through the remainning UVs.

 

Thanks for the reply. It would also be nice if all UV streams can be selected as either .x .xy .xyz or .xyzw just like the one in Custom =D.