/// <summary>
/// Multiplies matrix with a V4f.
/// </summary>
public static V4f Multiply(M22f mat, V4f vec)
{
return(new V4f(mat.M00 * vec.X + mat.M01 * vec.Y,
mat.M10 * vec.X + mat.M11 * vec.Y,
vec.Z,
vec.W));
}
/// <summary>
/// Multiplacation of a <see cref="Scale3f"/> with a <see cref="V4f"/>.
/// </summary>
public static V4f Multiply(Scale3f scale, V4f vec)
{
return(new V4f(scale.X * vec.X,
scale.Y * vec.Y,
scale.Z * vec.Z,
vec.W));
}
public static V4f Transform(this Rot2f rot, V4f v)
{
float a = Fun.Cos(rot.Angle);
float b = Fun.Sin(rot.Angle);
return(new V4f(a * v.X + -b * v.Y,
b * v.X + a * v.Y,
v.Z, v.W));
}
/// <summary>
/// Calculates the centroid for a given set of V4fs.
/// </summary>
public static V4f ComputeCentroid(this V4f[] vectors)
{
V4f sum = V4f.Zero;
for (var i = 0; i < vectors.Length; i++)
{
sum += vectors[i];
}
return(sum / (float)vectors.Length);
}
/// <summary>
/// Calculates the centroid for a given set of V4fs.
/// </summary>
public static V4f ComputeCentroid(this V4f[] vectors, int[] indices)
{
V4f sum = V4f.Zero;
for (var i = 0; i < indices.Length; i++)
{
sum += vectors[indices[i]];
}
return(sum / (float)indices.Length);
}
/// <summary>
/// Calculates the sum for a given set of V4fs.
/// </summary>
public static V4f Sum(this IEnumerable <V4f> vectors)
{
V4f sum = V4f.Zero;
foreach (var e in vectors)
{
sum += e;
}
return(sum);
}
/// <summary>
/// Calculates the sum for a given set of V4fs.
/// </summary>
public static V4f Sum(this V4f[] vectors)
{
V4f sum = V4f.Zero;
for (var i = 0; i < vectors.Length; i++)
{
sum += vectors[i];
}
return(sum);
}
/// <summary>
/// Calculates a weighted centroid for a given array of V4fs.
/// </summary>
public static V4f ComputeCentroid(this V4f[] vectors, float[] weights)
{
V4f sum = V4f.Zero;
float weightSum = 0;
for (int i = 0; i < vectors.Length; i++)
{
sum += weights[i] * vectors[i];
weightSum += weights[i];
}
return(sum / weightSum);
}
/// <summary>
/// Calculates the centroid for a given set of V4fs.
/// </summary>
public static V4f ComputeCentroid(this IEnumerable <V4f> vectors)
{
V4f sum = V4f.Zero;
int count = 0;
foreach (var e in vectors)
{
sum += e;
count++;
}
return(sum / (float)count);
}
/// <summary>
/// Calculates a weighted centroid for vectors and weights given by indices.
/// Sum(vectors[indices[i]] * weights[indices[i]]) / Sum(weights[indices[i]].
/// </summary>
public static V4f ComputeCentroid(this V4f[] vectors, float[] weights, int[] indices)
{
V4f sum = V4f.Zero;
float weightSum = 0;
for (int i = 0; i < indices.Length; i++)
{
var w = weights[indices[i]];
sum += w * vectors[indices[i]];
weightSum += w;
}
return(sum / weightSum);
}
public static V4f Multiply(Rot2f rot, V4f vec)
{
float a = (float)System.Math.Cos(rot.Angle);
float b = (float)System.Math.Sin(rot.Angle);
return(new V4f(a * vec.X +
b * vec.Y,
-b * vec.X +
a * vec.Y,
vec.Z,
vec.W));
}
public static V4f InvTransform(this Rot2f rot, V4f v) => Transform(rot.Inverse, v);
public void Write(V4f x)
{
Write(x.X); Write(x.Y); Write(x.Z); Write(x.W);
}
public QuaternionF(V4f v)
{
W = v.X;
X = v.Y; Y = v.Z; Z = v.W;
}
/// <summary>Computes MD5 hash of given data.</summary>
public static Guid ComputeMd5Hash(this V4f x)
=> ComputeMd5Hash(bw => { bw.Write(x.X); bw.Write(x.Y); bw.Write(x.Z); bw.Write(x.W); });
