sampler Tex: register(s0);
sampler Env: register(s1);
float off;

float4 main(float2 texCoord: TEXCOORD0, float3 viewVec: TEXCOORD1) : COLOR {
        const float4 waterColor = float4(0.3, 0.4, 1.0, 0.0);

        float4 s = tex2D(Tex, texCoord) - 0.5;
        float sobelX = s.z;
        float sobelY = s.w;

        float3 normal = float3(sobelX, 0.04, sobelY);

        normal  = normalize(normal);
        viewVec = normalize(viewVec);

        float3 reflVec = reflect(viewVec, normal);
        float4 refl = texCUBE(Env, reflVec) * 0.9;

        float3 refrVec = refract(viewVec, normal, 0.85);
        float4 refr = texCUBE(Env, refrVec) * waterColor;

        return lerp(refl, refr, -dot(viewVec, normal));
}