public static T RandomOrDefault <T>(this IEnumerable <T> ts, Thirdparty.Random r)
{
if (!ts.Any())
{
return(default(T));
}
return(ts.Random(r));
}
// Returns a random offset in the range [-1..1,-1..1] with a separable
// Gauss distribution with 'samples' values taken for each axis
public static float2 Gauss2D(this Thirdparty.Random r, int samples)
{
return(new float2(Gauss1D(r, samples), Gauss1D(r, samples)));
}
public static float Gauss1D(this Thirdparty.Random r, int samples)
{
return(Graphics.Util.MakeArray(samples, _ => (float)r.NextDouble() * 2 - 1f)
.Sum() / samples);
}
public static int2 ChooseRandomCell(this World w, Thirdparty.Random r)
{
return(new int2(
r.Next(w.Map.Bounds.Left, w.Map.Bounds.Right),
r.Next(w.Map.Bounds.Top, w.Map.Bounds.Bottom)));
}
// Sampled a N-sample probability density function in the range [-1024..1024]
// 1 sample produces a rectangular probability
// 2 samples produces a triangular probability
// ...
// N samples approximates a true gaussian
public static WRange FromPDF(Thirdparty.Random r, int samples)
{
return(new WRange(Exts.MakeArray(samples, _ => r.Next(-1024, 1024))
.Sum() / samples));
}
// Sampled a N-sample probability density function in the range [-1024..1024, -1024..1024]
// 1 sample produces a rectangular probability
// 2 samples produces a triangular probability
// ...
// N samples approximates a true gaussian
public static WVec FromPDF(Thirdparty.Random r, int samples)
{
return(new WVec(WRange.FromPDF(r, samples), WRange.FromPDF(r, samples), WRange.Zero));
}
public static T Random <T>(this IEnumerable <T> ts, Thirdparty.Random r)
{
var xs = ts.ToArray();
return(xs[r.Next(xs.Length)]);
}
public static float Gauss1D(this Thirdparty.Random r, int samples)
{
return(Exts.MakeArray(samples, _ => r.NextFloat() * 2 - 1f)
.Sum() / samples);
}