Shader with animated transparency map

I am looking for a way to animate an object's transparency map. The object has a static main texture but the map that is used to alpha blend the main texture should be animated by manipulating the UV coordinates of the transparency map over time, like a frame animation. It's not just a matter of setting an object's opacity, but I am looking for something that would allow me to essentially define a different alpha map whenever I want to, like a transparency sprite animation to play through, without ever changing the main texture at all.

Does such a shader exist and where would I find it?

 

Any shader you find can be modified to do this really. It's just a matter of defining another texture input and sampling that input (with modified UV value) to use as your output Alpha value instead of using the alpha channel from the sampled _MainTex.

So, in the Properties section of your shader you'd add

_AlphaTex ("Alpha Texture", 2D) = "white" {}

Then, somewhere in your CGPROGRAM section of the shader, you'd have

sampler2D _AlphaTex;

to create the actual shader field for that material property above to assign its texture to.

Then, in your frag or surf function of the shader, you would do

float alpha = tex2D(_AlphaTex, animatedUV).r;

(assuming you've already done your UV calculation), and now you've got your alpha value to use however you want. In the case of a transparent surface shader it's as simple as just assigning it to

o.Alpha

.

 

Thank you so much!