public static XMVector FresnelTerm(XMVector cosIncidentAngle, XMVector refractionIndex)
{
Debug.Assert(!XMVector4.IsInfinite(cosIncidentAngle), "Reviewed");
//// Result = 0.5f * (g - c)^2 / (g + c)^2 * ((c * (g + c) - 1)^2 / (c * (g - c) + 1)^2 + 1) where
//// c = CosIncidentAngle
//// g = sqrt(c^2 + RefractionIndex^2 - 1)
XMVector g = XMVector.MultiplyAdd(refractionIndex, refractionIndex, XMGlobalConstants.NegativeOne);
g = XMVector.MultiplyAdd(cosIncidentAngle, cosIncidentAngle, g);
g = g.Abs().Sqrt();
XMVector s = XMVector.Add(g, cosIncidentAngle);
XMVector d = XMVector.Subtract(g, cosIncidentAngle);
XMVector v0 = XMVector.Multiply(d, d);
XMVector v1 = XMVector.Multiply(s, s).Reciprocal();
v0 = XMVector.Multiply(XMGlobalConstants.OneHalf, v0);
v0 = XMVector.Multiply(v0, v1);
XMVector v2 = XMVector.MultiplyAdd(cosIncidentAngle, s, XMGlobalConstants.NegativeOne);
XMVector v3 = XMVector.MultiplyAdd(cosIncidentAngle, d, XMGlobalConstants.One);
v2 = XMVector.Multiply(v2, v2);
v3 = XMVector.Multiply(v3, v3);
v3 = v3.Reciprocal();
v2 = XMVector.MultiplyAdd(v2, v3, XMGlobalConstants.One);
return(XMVector.Multiply(v0, v2).Saturate());
}
public static bool IsInfinite(XMVector p)
{
return(XMVector4.IsInfinite(p));
}
public static bool IsInfinite(XMVector c)
{
return(XMVector4.IsInfinite(c));
}
public static bool IsInfinite(XMVector q)
{
return(XMVector4.IsInfinite(q));
}
