/// <summary>
/// For the incident vector I and surface normal N,
/// and the ratio of indices of refraction eta,
/// return the refraction vector.
/// </summary>
/// <param name="I"></param>
/// <param name="N"></param>
/// <returns></returns>
public static Vec2f Refract(Vec2f I, Vec2f N, float eta)
{
//TODO: Use operatores instead of function madness.
float dotValue = Dot(N, I);
float k = 1.0f - eta * eta * (1.0f - dotValue * dotValue);
if (k < 0.0f)
{
return(Vec2f.Zero);
}
else
{
return(eta * I - (eta * dotValue + MathF.Sqrt(k)) * N);
}
//return eta * I - (eta * dotValue + MathFunctions.Sqrt(k)) * N;
//TODO: Use operatores instead of function madness.
//return Multiply(Subtract(Multiply(I, eta), (eta * dotValue + MathFunctions.Sqrt(k))), N);
//return Multiply(Subtract(Multiply(I, eta),sdf), N);
//return eta * I - (eta * dotValue + MathFunctions.Sqrt(k)) * N;
// return eta * I - (eta * dotValue + MathFunctions.Sqrt(k)) * N;
}
public static float InverseSqrt(float f)
{
return((float)1.0f / MathF.Sqrt(f));
}
public static unsafe float InverseSqrt(float x)
{
return(1.0f / MathF.Sqrt(x));
}