[Unity Error correction] Too Many texture interpolators would is used for forwardbase

The error message in the Unity console is as follows:

Shader error in ' Custom/sky_shader ': Too Many texture interpolators would is used for Forwardbase pass at line 19

The reason for the error is that in the shader, additional UV variable information is defined in the structure input that is greater than or equal to 3.

Here is the shader input structure for the error

struct Input {
			float2 offset1;
			FLOAT2 Offset2;
			FLOAT2 Offset3;
			FLOAT4 Pos;
			Fixed4 color;
		};

The following is the corrected shader input structure

struct Input {
			float2 offset1;
			FLOAT2 Offset2;
			FLOAT4 Pos;
			Fixed4 color;
		};

So if you need to offset3 variable record information how to do it, what I learned is not a very good way, is to use Offset1 and offset2 to do changes instead of Offset3 do information recording processing.

In general Main_tex,bumpmap and Specmap can use the same UV set.