struct Input_ {
    float3 normal_ : TEXCOORD0;
    float3 incident_ : TEXCOORD1;
    float2 coord_ : TEXCOORD2;
    float4 position_ : TEXCOORD3;
};

struct Output_ {
    float4 color_ : COLOR;
};

Output_ main(
    in Input_ _in,
    uniform samplerCUBE environment,
    uniform sampler2D bottom
) {
    Output_ _out;

    float3 reflV = reflect(_in.incident_, _in.normal_);
    float4 reflected = texCUBE(environment, reflV);

    float3 refr3 = refract(_in.incident_, _in.normal_, 1.5f);
    float2 refr2 = refr3.xy * ((_in.position_.z + 3.0) / -refr3.z);
    float4 refracted = tex2D(bottom, _in.coord_ + refr2);

    float coefficient = clamp(0.5f + 0.4f * pow(1 + dot(_in.incident_, _in.normal_), 2.0f), 0.0f, 1.0f);
    _out.color_ = lerp(refracted, reflected, coefficient);

    return _out;
}