public static XMVector RefractV(XMVector incident, XMVector normal, XMVector refractionIndex)
{
//// Result = RefractionIndex * Incident - Normal * (RefractionIndex * dot(Incident, Normal) +
//// sqrt(1 - RefractionIndex * RefractionIndex * (1 - dot(Incident, Normal) * dot(Incident, Normal))))
XMVector zero = XMVector.Zero;
XMVector incidentDotNormal = XMVector4.Dot(incident, normal);
// R = 1.0f - RefractionIndex * RefractionIndex * (1.0f - IDotN * IDotN)
XMVector r = XMVector.NegativeMultiplySubtract(incidentDotNormal, incidentDotNormal, XMGlobalConstants.One);
r = XMVector.Multiply(r, refractionIndex);
r = XMVector.NegativeMultiplySubtract(r, refractionIndex, XMGlobalConstants.One);
if (XMVector4.LessOrEqual(r, zero))
{
// Total internal reflection
return(zero);
}
else
{
// R = RefractionIndex * IDotN + sqrt(R)
r = r.Sqrt();
r = XMVector.MultiplyAdd(refractionIndex, incidentDotNormal, r);
// Result = RefractionIndex * Incident - Normal * R
XMVector result = XMVector.Multiply(refractionIndex, incident);
result = XMVector.NegativeMultiplySubtract(normal, r, result);
return(result);
}
}
public static XMVector AngleBetweenNormals(XMVector n1, XMVector n2)
{
return(XMVector4
.Dot(n1, n2)
.Clamp(XMGlobalConstants.NegativeOne, XMGlobalConstants.One)
.ACos());
}
public static XMVector DotCoord(XMVector p, XMVector v)
{
//// Result = P[0] * V[0] + P[1] * V[1] + P[2] * V[2] + P[3]
XMVector v3 = XMVector.Select(XMGlobalConstants.One, v, XMGlobalConstants.Select1110);
return(XMVector4.Dot(p, v3));
}
public static XMVector Reflect(XMVector incident, XMVector normal)
{
//// Result = Incident - (2 * dot(Incident, Normal)) * Normal
XMVector result = XMVector4.Dot(incident, normal);
result = XMVector.Add(result, result);
result = XMVector.NegativeMultiplySubtract(result, normal, incident);
return(result);
}
public static XMVector AngleBetweenVectors(XMVector v1, XMVector v2)
{
XMVector l1 = XMVector4.ReciprocalLength(v1);
XMVector l2 = XMVector4.ReciprocalLength(v2);
XMVector dot = XMVector4.Dot(v1, v2);
l1 = XMVector.Multiply(l1, l2);
return(XMVector
.Multiply(dot, l1)
.Clamp(XMGlobalConstants.NegativeOne, XMGlobalConstants.One)
.ACos());
}
public static XMVector LengthSquare(XMVector v)
{
return(XMVector4.Dot(v, v));
}
public static XMVector Dot(XMVector p, XMVector v)
{
return(XMVector4.Dot(p, v));
}
public static XMVector Dot(XMVector q1, XMVector q2)
{
return(XMVector4.Dot(q1, q2));
}
