4.22 Mesh drawing pipline breaks imposter materials


I’ve been using the imposter baker from Ryan Brucks and it used to work in the versions of unreal priory to 4.22.
I saw that the mesh drawing pipeline has been updated and I’m guessing some code needs to also be re adapted to the new pipeline.

Currently I run into the following error in the material editor:

[SM5] Shader attempted to bind the Primitive uniform buffer even though Vertex Factory FLocalVertexFactory computes a PrimitiveId per-instance. This will break auto-instancing. Shaders should use GetPrimitiveData(Parameters.PrimitiveId).Member instead of Primitive.Member.

Ryan is using some custom code in the material in the WorldtoLoc nodes :

return mul(InWorldVector, transpose(Parameters.InstanceLocalToWorld));
return mul(InWorldVector, (MaterialFloat3x3)Primitive.WorldToLocal);

And also :

float3 temp;
temp.x = length(TransformLocalVectorToWorld(Parameters, float3(1,0,0)));
temp.y = length(TransformLocalVectorToWorld(Parameters, float3(0,1,0)));
temp.z = length(TransformLocalVectorToWorld(Parameters, float3(0,0,1)));
return mul(InWorldVector, (MaterialFloat3x3)transpose(Parameters.InstanceLocalToWorld)) / (temp*temp);
return mul(InWorldVector, (MaterialFloat3x3)Primitive.WorldToLocal);

Also the material seems to break at the vertexInterpolator node.

As an environment artist, my programming knowledge is abysmal, any help or direction how to solve this issue would be greatly appreciated.

I found a fix for a scaling issue I wanted to share. Test it out if this works for you.
The screenshot/fix is applied in the function “Impostor_ThreeFrameBlend” and fixed the scaling issues I had.

Hope this might still help someone.

That #else statement part that says (MaterialFloat3x3)Primitive.WorldToLocal → you need to replace that parameter with (MaterialFloat3x3)GetPrimitiveData(Parameters.PrimitiveId).WorldToLocal

In all instances of WorldToLoc node. There are 5 of them in total.
You could use Window->Find Results inside the Blueprint and type in “WorldToLoc” into the search bar to locate all of them easily

1 Like