openmw/files/shaders/lib/water/fresnel.glsl

#ifndef LIB_WATER_FRESNEL
#define LIB_WATER_FRESNEL

float fresnel_dielectric(vec3 incoming, vec3 normal, float eta)
{
    float c = abs(dot(incoming, normal));
    float g = eta * eta - 1.0 + c * c;
    float result;

    if (g > 0.0)
    {
        g = sqrt(g);
        float A =(g - c)/(g + c);
        float B =(c *(g + c)- 1.0)/(c *(g - c)+ 1.0);
        result = 0.5 * A * A *(1.0 + B * B);
    }
    else
    {
        result = 1.0;  /* TIR (no refracted component) */
    }

    return result;
}

#endif