How to update shader parameters in a shader with stencil (UI.Mask) ?

I'm trying in a run-time update parameters for a shader in a material for an element that is a child element of a UI.Mask.

Problem is that if I include this code in my shader:

Code (CSharp):

1.  
2.         _StencilComp ("Stencil Comparison", Float) = 8
3.         _Stencil ("Stencil ID", Float) = 0
4.         _StencilOp ("Stencil Operation", Float) = 0
5.         _StencilWriteMask ("Stencil Write Mask", Float) = 255
6.         _StencilReadMask ("Stencil Read Mask", Float) = 255
7.         _ColorMask ("Color Mask", Float) = 15
8.  

and in SubShader section

Code (CSharp):

1.  
2.         Stencil
3.         {
4.             Ref [_Stencil]
5.             Comp [_StencilComp]
6.             Pass [_StencilOp]
7.             ReadMask [_StencilReadMask]
8.             WriteMask [_StencilWriteMask]
9.         }
10.         ColorMask [_ColorMask]
11.  

My code in C# script (inside Update()):

Code (CSharp):

1. m_mat.SetColor("_Color", m_color);

is executed only once. All subsequent calls to .SetColor do not update the value.

If I remove stencil code, everything works and color changing every frame, but then mask does not have any effect and a whole image is revealed. It is very similar to http://forum.unity3d.com/threads/masked-ui-elements-shader-not-updating.371542/. But I cannot change parameter globally as I have multiple instances of the same material and I need different parameters.

Any ideas how to fix it? I looked and googled everywhere, but could not find any working solution...

 

Not sure if you ever figured out the issue, but I just spent some time on the same thing and am updating the similar threads I read without an answer.

The Mask object causes a modified material to be returned so it is no longer rendering the base material texture but a "on-the-fly" material. Assuming you are using an Image using setColor on the materialForRendering property of Image will set the correct material if a mask is involved.

 

Thanks