public Seed(Vector2 point, IVector2Field field, IVector2Field alternativeField)
: this()
{
Point = point;
Field = field;
AlternativeField = alternativeField;
}
public static IVector2Field Inverse(this IVector2Field field)
{
Contract.Requires(field != null);
Contract.Ensures(Contract.Result <IVector2Field>() != null);
return(new Inverse(field));
}
public static Vector2 TraceVectorField(this IVector2Field field, Vector2 position, Vector2 previous, float maxSegmentLength)
{
Contract.Requires(field != null);
Contract.Requires(maxSegmentLength > 0);
var first = previous;
//Extended naieve tracing (accumulate naieve traces, stop once we hit sample OR length limit)
float lengthSum = 0;
var result = Vector2.Zero;
for (var i = 0; i < 10 && lengthSum < maxSegmentLength; i++)
{
var d = field.SingleTraceVectorField(position, previous);
var l = d.Length();
lengthSum += d.Length();
result += d;
previous = d;
//escape if the curvature is too much
if (Vector2.Dot(first, d / l) < 0.9961f)
{
break;
}
}
return(result);
}
private static Vector2 SingleTraceVectorField(this IVector2Field field, Vector2 position, Vector2 previous)
{
Contract.Requires(field != null);
//Naieve tracing
//return field.CorrectedSample(position, previous);
//RK4
var k1 = field.CorrectedSample(position, previous);
var k2 = field.CorrectedSample(position + k1 / 2f, previous);
var k3 = field.CorrectedSample(position + k2 / 2f, previous);
var k4 = field.CorrectedSample(position + k3, previous);
return(CorrectVectorDirection(k1 / 6f + k2 / 3f + k3 / 3f + k4 / 6f, previous));
}
private ResampleAndRescale(Vector2[,] major, Vector2 min, Vector2 max)
{
_min = min;
_size = max - min;
_zeroSize = (Math.Abs(_size.X) < float.Epsilon || Math.Abs(_size.Y) < float.Epsilon);
if (_zeroSize)
{
return;
}
_majorEigenVectors = major;
_xLength = major.GetLength(0) - 1;
_yLength = major.GetLength(1) - 1;
_minor = new EigenAccessor(true, this);
_major = new EigenAccessor(false, this);
}
public Heightmap(BaseScalarField height)
{
Contract.Requires(height != null);
_gradient = new Gradient(height);
}
private static IEnumerable <Seed> RandomSeedsInBounds(Func <double> random, int count, IVector2Field major, IVector2Field minor, Vector2 min, Vector2 max, Func <Vector2, bool> isOutOfBounds)
{
var extent = (max - min);
for (int i = 0; i < count; i++)
{
var p = new Vector2((float)random() * extent.X, (float)random() * extent.Y) + min;
if (isOutOfBounds(p))
{
i--;
}
else
{
yield return(new Seed(p, major, minor));
}
}
}
private static IEnumerable <Seed> SeedsAlongEdge(Region region, BaseScalarField distanceField, IVector2Field major, IVector2Field minor)
{
float d = 0;
Vector2?previous = null;
foreach (var vertex in region.Vertices)
{
if (previous.HasValue)
{
var pos = previous.Value;
var v = vertex - previous.Value;
var length = v.Length();
var dir = v / length;
for (int i = 0; i < length; i++)
{
var separation = distanceField.Sample(pos + dir * i);
d += separation;
if (d >= separation)
{
yield return(new Seed(pos + dir * i, major, minor));
d -= separation;
}
}
}
previous = vertex;
}
}
private static Vector2 CorrectedSample(this IVector2Field field, Vector2 position, Vector2 baseDirection)
{
Contract.Requires(field != null);
return(CorrectVectorDirection(field.Sample(position), baseDirection));
}
public Inverse(IVector2Field field)
{
Contract.Requires(field != null);
_field = field;
}
