dynamic batching particle,rotate wrong

Code (CSharp):

1. half3x3 roMatrixZ={
2.                       half3(cos(dxTime),-sin(dxTime),0),
3.                       half3(sin(dxTime),cos(dxTime),0),
4.                       half3(0.0,0.0,1.0)
5.                   };
6.               half3 p=pos.xyz;
7.          pos.xyz=mul(p,roMatrixZ);
8.          o.pos = mul(UNITY_MATRIX_MVP,pos);

When camera see both particles,it seems particlses rotate around camera,not around themself,strange....what is wrong with this?

 

help

 

Can you just use the built in rotation over lifetime parameter in the unity particle system?

 

This is custom particle system which moving in shader,not unity built in particle system.

 

can you rotate the UV in the vertex shader?

Code (CSharp):

1.  
2.  
3. float2 uvrot = v.texcoord - 0.5;
4. float sinX = sin(angleInRadians);
5. float cosX = cos(angleInRadians);
6. float sinY = sin(angleInRadians);
7. float2x2 rotationMatrix = float2x2(cosX, -sinX, sinY, cosX);
8. o.rotatedUV = mul(uvrot, rotationMatrix) + 0.5;

 

i rotate the position, not uv.if u want rotation uv, u can.

 

any body help?this is unity bug??

 

Are the particles in viewspace not worldspace? Also dynamic batching changes the vertex positions.

 

yes,it seems like that,how to fixed?I don't want to update the position in CPU,C# calculates so many positions not good...

 

any help??this is a bug??

 

Any help?

 

Up

 

Nobody help?

 

Day day up

 

this is not unity bug???confused..

 

what 's up?

 

Looks like you're rotating the particles around the pivot of the model, when something's is dynamically batched its pivot becomes the camera as multiple meshes are batched to 1 model and can't have multiple pivots, vertex positions are modified so they keep the same world position but are now relative to the camera.

You could store the pivot of rotation in the vertex positions i.e. (0,0,0) and use other data to store the vertex positions, such as vertex color, as this is unmodified by batching. The shader might look something like this (untested);

Code (CSharp):

1. half3x3 roMatrixZ={
2.     half3(cos(dxTime),-sin(dxTime),0),
3.     half3(sin(dxTime),cos(dxTime),0),
4.     half3(0.0,0.0,1.0)
5. };
6. half3 p = v.color.xyz;
7. pos.xyz = mul(p,roMatrixZ) + v.vertex;
8. o.pos = mul(UNITY_MATRIX_MVP,pos);

Then the pivot should be correct, you'll still have the issue of it rotating around the camera's axis though, you could maybe replace half3(0.0,0.0,1.0) with a shader property?

 

thanks reply~~ this idea maybe can work if use native c++.i think when the batching particles is moving in runtime, if i use c# to change the position then transite to shader,the performance is not good,and if i use c++ dll to moving,maybe worse.. So, whether this is unity BUG?can fixed in lower_level?

 

that shouldnt need any plugin, just a change to your mesh to write vertex positions to vertex color and write (0,0,0) to positions, this can be done though scripting.

its not really a bug just a caveat of the batching system,you could also stop them batching by giving them diffeeent materials

 

I known your meaning,I think about update the vertices position saved to color in runtime,when moving particles systems,the performance maybe have issue?

 

Oh yeah updating the positions at runtime in the update loop might perform better if it were done in a plugin, but that's a separate issue from the rotation

 

May have other better idea? I want to scale,change color,rotate the particle systems,the dynamic batch will break that.It 's very difficult to do that....

 

any help?

 

Can get the base position when batching? if can get that,maybe like this: initPos=v.vertex-batchingbasepos;
mul(initPos,roMatrixZ)+batchingbasepos ;will work.

 

any help?

 

Same issue now If performance is not an issue you can try "DisableBatching" = "True" in the tag section, but for me performance matters so I can't do it.

EDIT: Unity now allows GPU Instancing. It solved problem

 

en ,unity 2018.1 version will work