Distortion Image Effect.

Hello! I am completely new to shaders, been following a couple of tutorials and ran into a problem that I can't get my head around, so I hope someone is able to explain this to me.

Code (CSharp):

1.             float4 frag(v2f i) : SV_Target
2.             {
3.                 float2 disp = tex2D(_Noise, i.uv).rg;
4.                 disp = ((disp * 2) - 1) * _Strength;
5.                 float4 col = tex2D(_MainTex, i.uv + disp);
6.                 return col;
7.             }

This is a simple shader, that takes a Noise texture, picks it's red and green values (that would control x and y), converts them to -1;1 values and then adds them to the MainTexture thus distorting it. This part works great and everything is fine. The problem happens then I start to experiment with the code. Let's say I want to distort the image by 0.1 in both x and y axis. So I wrote this :

Code (CSharp):

1.                 i.uv.x += 0.1;
2.                 i.uv.y += 0.1;
3.                 float4 col = tex2D(_MainTex, i.uv);

and it works fine. I can see my image is distorted in both axis. So I took one step further and tried to write the code like this:

Code (CSharp):

1.                 float2 disp = (0.1, 0.1);
2.                 float4 col = tex2D(_MainTex, i.uv + disp);
3.                 return col;

This doesn't change the result, so it's still the same. However, I found that now the first number ( that I thought was controlling x axis ) does not do anything. This is where I don't understand why. Now both axis are always the same and both are dependent on the second number. So this:

Code (CSharp):

1. float2 disp = (0.0, 0.2);

is distorting both x and y axis by 0.2 for some reason.

Thank you very much for any kind of explanation.

 

You need a constructor...

float2 disp = float2(0.0,0.2);