Dvornik/Distort

Shader "Dvornik/Distort" {
    Properties{
        _Refraction("Refraction", Range(-10.00, 10.0)) = 0
        _MainTex("Sprite Texture", 2D) = "white" {}
        _DistortTex("Distort",2D) = "white" {}
    }

    SubShader{

        Tags{ "RenderType" = "Transparent" "Queue" = "Overlay" }
        LOD 100

        GrabPass{

        }

        CGPROGRAM
            #pragma surface surf NoLighting
            #pragma vertex vert

            fixed4 LightingNoLighting(SurfaceOutput s, fixed3 lightDir, fixed atten) {
                fixed4 c;
                c.rgb = s.Albedo;
                c.a = s.Alpha;
                return c;
            }

            sampler2D _GrabTexture;
            sampler2D _MainTex;
            sampler2D _DistortTex;
            float _Refraction;

            float4 _DistortTex_TexelSize;

            struct Input {
                float2 uv_MainTex;
                float2 uv_DistortTex;
                float3 color;
                float4 grabScreenPos;
                INTERNAL_DATA
            };

            void vert(inout appdata_full v, out Input o) {
                UNITY_INITIALIZE_OUTPUT(Input,o);
                o.color = v.color;
                float4 clipPos = mul(UNITY_MATRIX_MVP, v.vertex);
                o.grabScreenPos = ComputeGrabScreenPos(clipPos);
            }

            void surf(Input IN, inout SurfaceOutput o) {
                float4 main = tex2D(_MainTex, IN.uv_MainTex);
                float4 dist = tex2D(_DistortTex, IN.uv_DistortTex);
                float3 distort = float3(dist.r - 0.5, dist.g - 0.5, dist.b - 0.5);
                float2 offset = distort * _Refraction * _DistortTex_TexelSize.xy;
                //float4 bgColor = tex2Dproj(_GrabTexture, IN.screenPos);
                IN.grabScreenPos.xy = offset + IN.grabScreenPos.xy;
                float4 refrColor = tex2Dproj(_GrabTexture, IN.grabScreenPos);
                float alph = (main.a-0.5)*2;
                //if (alph <= 0) {
                    //o.Emission = refrColor.rgb;
                    o.Emission = main.rgb * main.a * main.a + (1 - main.a) * refrColor.rgb;
                /*}
                else {
                    o.Emission = main.rgb * alph + (1-alph) * refrColor.rgb;
                }*/
                o.Alpha = alph;
            }
        ENDCG
    }
}