Is it possible to re-use a texture within a shader on separate uv channels?

Questions & Answers
1

Hi,
Im trying to optimise a my shader as far as possible,
I have a single texture that i want to split into 2 essentially, here’s what im trying to do:
1 texture -
rgd = uv1
a = uv2

I have an asset that has a diffuse texture layout in uv1 and an AO Bake hidden in the alpha channel that requires uv2.

Currently I am having to pull in the texture with a
sampler2D - attach that to a fixed4 and apply the uv1 to it
but then to achieve the second uv2 I need to repeat the above? im also having to use two separate texture slots for the same texture?
is there a more efficient way of doing this?

my current shader below:

Shader "Custom/OptimalDiffuse_uv2-AOBake" {

Properties
{
	_MainTex ("Main Texture (RGB)", 2D) = "white" {}
	_AOBake ("Main Texture (A) - AO Bake", 2D) = "white" {}
}

SubShader {
	Tags {"Queue"="Geometry" "IgnoreProjector"="True" "RenderType"="opaque"}
	LOD 250

CGPROGRAM
#pragma surface surf Lambert noforwardadd 


sampler2D _MainTex;
sampler2D _AOBake;

struct Input
{
fixed2 uv_MainTex;
fixed2 uv2_AOBake;
};


void surf (Input IN, inout SurfaceOutput o) {
	fixed4 c = tex2D (_MainTex, IN.uv_MainTex);
	fixed4 c2 = tex2D (_AOBake, IN.uv2_AOBake);
	o.Albedo = (c.rgb * c2.a);
}

ENDCG
}

Fallback "Mobile/Diffuse"
}

Any Advice would really be welcome, Thanks.

2

You can definitely have a single texture, which is looked-up (tex2D’d) multiple times, with different UVs.

Maybe you can compute uv2 from uv1. Otherwise you’ll have to figure out how to tell Unity to send just a UV2 array.

But I’m not sure that sending the same texture twice is even a problem. The texture manager usually handles all textrues for all draws. So should notice AOBake uses an already loaded repeat.