/// <summary>
/// Retrieve index to the discrete PDF where its cumulative distribution matches the random variable x1 [0, 1].
/// Uses binary search O(log n).
/// </summary>
public int Sample(double x1)
{
var range = m_cdf.Length;
var valueToFind = x1 * m_cdf[range - 1]; // x1 * sum -> CDF threshold to find
var i0 = 0;
// binary search
while (range > 0)
{
var halfRange = range >> 1;
var center = i0 + halfRange;
// check if value is left or right
if (m_cdf[center] <= valueToFind)
{
// right half
i0 = center + 1;
range -= halfRange + 1;
}
else
{
// left half
range = halfRange;
}
}
return(Fun.Clamp(i0 - 1, 0, m_cdf.Length - 2));
}
/// <summary>
/// Creates a quaternion representing a rotation from one
/// vector into another.
/// </summary>
public __rot3t__(__v3t__ from, __v3t__ into)
{
var a = from.Normalized;
var b = into.Normalized;
var angle = Fun.Clamp(__v3t__.Dot(a, b), -1, 1).Acos();
var angleAbs = angle.Abs();
__v3t__ axis;
// some vectors do not normalize to 1.0 -> Vec.Dot = -0.99999999999999989 || -0.99999994f
// acos => 3.1415926386886319 or 3.14124632f -> delta of 1e-7 or 1e-3
if (angle < __rotIntoEps__)
{
axis = a;
angle = 0;
}
else if (__pi__ - angleAbs < __rotIntoEps__)
{
axis = a.AxisAlignedNormal();
angle = __pi__;
}
else
{
axis = __v3t__.Cross(a, b).Normalized;
}
this = new __rot3t__(axis, angle);
}
/// <summary>
/// Spherical linear interpolation.
///
/// Assumes q1 and q2 are normalized and that t in [0,1].
///
/// This method does interpolate along the shortest arc
/// between q1 and q2.
/// </summary>
/// <param name="q1"></param>
/// <param name="q2"></param>
/// <param name="t">[0,1]</param>
/// <returns>Interpolant</returns>
public static Rot3f SlerpShortest(
Rot3f q1, Rot3f q2, double t
)
{
Rot3f q3 = q2;
float cosomega = Fun.Clamp(Rot3f.Dot(q1, q3), -1, 1);
if (cosomega < 0.0)
{
cosomega = -cosomega;
q3 *= -1; //q3 = -q3;
}
if (cosomega >= 1.0)
{
// Special case: q1 and q2 are the same, so just return one of them.
// This also catches the case where cosomega is very slightly > 1.0
return(q1);
}
double sinomega = System.Math.Sqrt(1 - cosomega * cosomega);
Rot3f result = new Rot3f();
if (sinomega * double.MaxValue > 1)
{
double omega = System.Math.Acos(cosomega);
float s1 = (float)(System.Math.Sin((1.0 - t) * omega) / sinomega);
float s2 = (float)(System.Math.Sin(t * omega) / sinomega);
result = s1 * q1 + s2 * q3;
}
else if (cosomega > 0)
{
// omega == 0
float s1 = 1.0f - (float)t;
float s2 = (float)t;
result = s1 * q1 + s2 * q3;
}
else
{
// omega == -pi
result.X = -q1.Y;
result.Y = q1.X;
result.Z = -q1.W;
result.W = q1.Z;
float s1 = (float)System.Math.Sin((0.5 - t) * System.Math.PI);
float s2 = (float)System.Math.Sin(t * System.Math.PI);
result = s1 * q1 + s2 * result;
}
return(result);
}
//# });
#endregion
#region LinCom
//# foreach (var it in Meta.IntegerTypes) { var itn = it.Name;
//# for (int tpc = 4; tpc < 7; tpc+=2) {
//# foreach (var rt in Meta.RealTypes) { var rtn = rt.Name; var rtc = rt.Caps[0];
public static __itn__ LinCom(
/*# tpc.ForEach(i => { */ __itn__ p__i__ /*# }, comma); */, ref Tup__tpc__ <__rtn__> w)
{
return((__itn__)Fun.Clamp(/*# tpc.ForEach(i => { */ p__i__ * w.E__i__ /*# }, add); */, (__rtn__)__itn__.MinValue, (__rtn__)__itn__.MaxValue));
}
